As filed with the Securities and Exchange Commission on April 28, 2006
1933 Act File No. 333-30810
1940 Act File No. 811-9819

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 [X]

Post-Effective Amendment No. 17 [X]

and

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT
OF 1940 [X]

Amendment No. 18 [X]

STATE STREET INSTITUTIONAL INVESTMENT TRUST

P.O. BOX 5049, BOSTON, MASSACHUSETTS 02206
(Address of Principal Executive Offices)

(617) 662-3909
(Registrant's Telephone Number)

Ryan M. Louvar, Secretary
State Street Bank and Trust Company
2 Avenue de Lafayette, 6th Floor
Boston, Massachusetts 02111
(Name and Address of Agent for Service)

Copy to:

Timothy W. Diggins
Ropes & Gray
One International Place
Boston, Massachusetts 02110-2624

It is proposed that this filing will become effective (check appropriate box):

[X] Immediately upon filing pursuant [ ] On (date) pursuant to paragraph (b)
to paragraph (b)

[ ] 60 days after filing pursuant to [ ] On (date) pursuant to paragraph
paragraph (a)(1) (a)(1) of Rule 485.

[ ] 75 days after filing pursuant to [ ] On (date) pursuant to paragraph
paragraph (a)(2) (a)(2) of Rule 485.

If appropriate, check the following box:

[ ] This post-effective amendment designates a new effective date for a
previously filed post-effective amendment.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET EQUITY 500 INDEX FUND
ADMINISTRATIVE SHARES


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Equity 500 Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Standard & Poor's 500(R) Composite Stock Price Index (the "S&P 500 Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the S&P 500 Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund is not managed according to traditional methods of "active" investment management, which involve the buying and selling of securities based upon economic, financial and market analysis and investment judgment. Instead, the Fund, using a "passive" or "indexing" investment approach, attempts to match, before expenses, the performance of the S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all stocks publicly traded in the United States. The Adviser seeks a correlation of 0.95 or better between the Fund's performance and the performance of the Index (1.00 would represent perfect correlation).

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The Fund intends to invest (either on its own or as part of a master-feeder structure) in all 500 stocks comprising the Index in proportion to their weightings in the Index. However, under various circumstances, it may not be possible or practicable to purchase all 500 stocks in those weightings. In those circumstances, the Fund may purchase a sample of the stocks in the Index in proportions expected by the Adviser to match generally the performance of the Index as a whole. In addition, from time to time stocks are added to or removed from the Index. The Fund may sell stocks that are represented in the Index, or purchase stocks that are not yet represented in the Index, in anticipation of their removal from or addition to the Index. In no event will the Fund invest less than 80% of its total assets in stocks in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

In addition, the Fund may at times purchase or sell futures contracts on the Index, or options on those futures, in lieu of investment directly in the stocks making up the Index. The Fund might do so, for example, in order to increase its investment exposure pending investment of cash in the stocks comprising the Index. Alternatively, the Fund might use futures or options on futures to reduce its investment exposure in situations where it intends to sell a portion of the stocks in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Stock values could decline generally or could under-perform other investments.

- Because the S&P 500 Index includes mainly large U.S. companies, the Fund's investments consist mainly of stocks of large U.S. companies. Returns on investments in stocks of large U.S. companies could trail the returns on investments in stocks of smaller companies.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the

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Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to replicate the performance of the Index may not correlate precisely with the return on the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

PERFORMANCE INFORMATION.

Bar chart

The bar chart below shows the performance of the Fund's Administrative Shares during the last several full calendar years. The chart provides some indication of the risks of investing in the Fund's Administrative Shares by showing changes in the Administrative Shares' performance from year to year. Please keep in mind that past performance does not necessarily indicate how the Fund's Administrative Shares will perform in the future.

STATE STREET EQUITY 500 INDEX FUND
ADMINISTRATIVE SHARES
TOTAL RETURN FOR THE CALENDAR YEAR ENDED DECEMBER 31

(STATE STREET EQUITY 500 INDEX FUND BAR CHART IN %)

2002                                                                            -22.31
2003                                                                             28.37
2004                                                                             10.63
2005                                                                              4.66

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During the period shown in the bar chart, the highest return for a quarter was 15.19% (quarter ended June 30, 2003) and the lowest return for a quarter was (17.37%) (quarter ended September 30, 2002).

AVERAGE ANNUAL TOTAL RETURN.

The information in the following table gives some indication of the risks of an investment in the Fund's Administrative Shares by comparing the Administrative Shares' performance to the performance of the S&P 500 Index over various periods of time.

The Fund's Administrative Shares' after-tax returns listed below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Additionally, actual after-tax returns depend on an investor's tax situation and may differ from those shown below, and after-tax returns are not relevant to investors who hold their shares through tax-deferred arrangements, such as individual retirement accounts.

                                                   SINCE THE INCEPTION
                                 PAST 1-YEAR        DATE OF THE FUND
                                (PERIOD ENDED          ANNUALIZED
                              DECEMBER 31, 2005)    (APRIL 18, 2001)
                              ------------------   -------------------
State Street Equity 500
  Index Fund Administrative
  Shares
     Return Before Taxes....          4.66%                2.45%
     Return After Taxes on
       Distributions........          4.08%                2.01%
     Return After Taxes on
       Distributions and
       Sale of Fund
       Shares...............          3.02%                1.88%
S&P 500 Index*..............          4.91%                2.72%


* The S&P 500 Index is a capitalization-weighted index of 500 widely held stocks recognized by investors to be representative of the stock market in general. The S&P 500 Index is unmanaged and does not reflect the actual cost of investing in the instruments that comprise the index. Additionally, the returns of the S&P 500 Index do not reflect the effect of fees, expenses and taxes.

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FEES AND EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold Administrative Shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1)................................   0.045%
Distribution (12b-1) Fees.........................    0.15%
Other Expenses....................................    0.05%
                                                     -----
Total Annual Fund Operating Expenses..............   0.245%
                                                     =====


1 This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

Example: This Example is intended to help you compare the cost of investing in the Fund's Administrative Shares with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund's Administrative Shares for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's Administrative Shares' operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR    3 YEARS    5 YEARS    10 YEARS
------    -------    -------    --------
   $25      $79       $138        $312

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all common stocks publicly traded in the United States, most of which are listed on the New York Stock Exchange, Inc. (the "NYSE"). Stocks in the S&P 500 Index are weighted according to their market capitalizations (i.e., the number of shares outstanding multiplied by the stock's current price). The companies selected for inclusion in the S&P 500 Index generally have the largest market value within their respective industries. The composition

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of the S&P 500 Index is determined by Standard & Poor's and is based on such factors as the market capitalization and trading activity of each stock and its adequacy as a representation of stocks in a particular industry group, and may be changed from time to time. "Standard & Poor's(R)," "S&P," "S&P 500," "Standard & Poor's 500" and "500" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by the Fund. The Fund is not sponsored, endorsed, sold or promoted by S&P, and S&P makes no representation regarding the advisability of investing in the Fund.

Index Futures Contracts and Related Options. The Fund may buy and sell futures contracts on the Index and options on those futures contracts. An "index futures" contract is a contract to buy or sell units of an index at an agreed price on a specified future date. Depending on the change in value of the Index between the time when the Fund enters into and terminates an index future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts on the Index will not correlate precisely with changes in the value of the Index. In those cases, use of futures contracts and related options might decrease the correlation between the return of the Fund and the return of the Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Index Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange

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or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security. Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Equity 500 Index Fund offers Administrative, Service and Class R Shares. Only the Administrative Shares of the Fund are discussed in this prospectus.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned

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subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.045% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund is available in the Fund's annual report dated December 31, 2005.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee. Key professionals involved in the day-to-day portfolio management for the Portfolio include the following:

JOHN TUCKER, CFA

Mr. Tucker is a Principal of SSgA and the Adviser. Mr. Tucker joined the firm in 1988 and is a Unit Head for the firm's Exchange Traded Funds Management Team. Mr. Tucker received a BA in Economics from Trinity College and an MS in Finance from Boston College. He is a member of the Boston Security Analysts Society.

MICHAEL FEEHILY, CFA

Mr. Feehily is a Principal of SSgA and the Adviser. Mr. Feehily joined the firm in 1992 and is head of the U.S. Equity Team within the Global Structured Products Team. Mr. Feehily is responsible for overseeing the management of all U.S. equity index funds for State Street Global Advisors. Mr. Feehily holds a Bachelor of Science degree in Finance, Investments, and

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Economics from Babson College and an MBA in Finance from Bentley College. He is a member of the Boston Security Analysts Society.

Additional information about the portfolio managers' compensation, other accounts managed by the portfolio managers, and the portfolio managers' ownership of securities in the Fund and the Portfolio is available in the Statement of Additional Information.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no mini-

9

mum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity that applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect

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and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's Administrative Shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.15%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

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DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

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FINANCIAL HIGHLIGHTS

The Financial Highlights table is intended to help you understand the Fund's Administrative Shares financial performance since inception. Certain information reflects financial results for a single share of the Administrative Shares. The total return in the table represents the rate that an investor would have earned on an investment in the Fund's Administrative Shares (assuming reinvestment of all dividends and distributions). This information has been audited by Ernst & Young LLP, whose report, along with the Fund's financial statements, are included in the Fund's annual report, which is available upon request. The financial information included in this table should be read in conjunction with the financial statements incorporated by reference in the Statement of Additional Information.

FINANCIAL HIGHLIGHTS FOR AN ADMINISTRATIVE SHARE OF BENEFICIAL INTEREST

OUTSTANDING THROUGHOUT THE PERIOD

                                 YEAR       YEAR       YEAR       YEAR       PERIOD
                                ENDED      ENDED      ENDED      ENDED        ENDED
                               12/31/05   12/31/04   12/31/03   12/31/02   12/31/01(A)
                               --------   --------   --------   --------   -----------
PER SHARE OPERATING
  PERFORMANCE(b):
NET ASSET VALUE, BEGINNING OF
  PERIOD.....................  $  10.10   $   9.34   $   7.36   $   9.62    $  10.00
                               --------   --------   --------   --------    --------
INVESTMENT OPERATIONS:
  Net investment income......      0.17*      0.17*      0.13*      0.11        0.08
  Net realized and unrealized
    gain (loss) on
    investments..............      0.30       0.82       1.95      (2.26)      (0.38)
                               --------   --------   --------   --------    --------
    Total from investment
      operations.............      0.47       0.99       2.08      (2.15)      (0.30)
                               --------   --------   --------   --------    --------
LESS DISTRIBUTIONS FROM:
  Net investment income......     (0.16)     (0.23)     (0.10)     (0.11)      (0.08)
                               --------   --------   --------   --------    --------
  Net increase (decrease) in
    net assets...............      0.31       0.76       1.98      (2.26)      (0.38)
                               --------   --------   --------   --------    --------
NET ASSET VALUE, END OF
  PERIOD.....................  $  10.41   $  10.10   $   9.34   $   7.36    $   9.62
                               ========   ========   ========   ========    ========
TOTAL RETURN(c)..............      4.66%     10.63%     28.37%    (22.31)%     (2.97)%
                               ========   ========   ========   ========    ========
RATIOS AND SUPPLEMENTARY
  DATA:
  Net Assets, End of Period
    (000s)...................  $195,725   $200,524   $182,037   $136,615    $171,774
  Ratios to average net
    assets:
    Operating expenses.......     0.245%     0.245%     0.245%     0.245%      0.245%(d)
    Net investment income....      1.64%      1.78%      1.54%      1.37%       1.18%(d)
  Portfolio turnover rate....         8%         9%        12%        13%         14%


(a) Administrative Shares commenced operations on April 18, 2001.

(b) The per share amounts and percentages include the Fund's proportionate share of income and expenses of the State Street Equity 500 Index Portfolio.

(c) Total return is calculated assuming a purchase of shares at net asset value on the first day and a sale at net asset value on the last day of each period reported. Distributions are assumed, for the purpose of this calculation, to be reinvested at net asset value per share on the respective payment dates. Total return for periods of less than one year is not annualized. Results represent past performance and are not indicative of future results.

(d) Annualized.

* Net investment income per share calculated using the average shares method.

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For more information about STATE STREET EQUITY 500 INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments is available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports are available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083 or the customer service center at the telephone number shown in the accompanying contract prospectus, if applicable. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-551-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET EQUITY 500 INDEX FUND
SERVICE SHARES


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Equity 500 Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Standard & Poor's 500(R) Composite Stock Price Index (the "S&P 500 Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the S&P 500 Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund is not managed according to traditional methods of "active" investment management, which involve the buying and selling of securities based upon economic, financial and market analysis and investment judgment. Instead, the Fund, using a "passive" or "indexing" investment approach, attempts to match, before expenses, the performance of the S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all stocks publicly traded in the United States. The Adviser seeks a correlation of 0.95 or better

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between the Fund's performance and the performance of the Index (1.00 would represent perfect correlation).

The Fund intends to invest (either on its own or as part of a master-feeder structure) in all 500 stocks comprising the Index in proportion to their weightings in the Index. However, under various circumstances, it may not be possible or practicable to purchase all 500 stocks in those weightings. In those circumstances, the Fund may purchase a sample of the stocks in the Index in proportions expected by the Adviser to match generally the performance of the Index as a whole. In addition, from time to time stocks are added to or removed from the Index. The Fund may sell stocks that are represented in the Index, or purchase stocks that are not yet represented in the Index, in anticipation of their removal from or addition to the Index. In no event will the Fund invest less than 80% of its total assets in stocks in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

In addition, the Fund may at times purchase or sell futures contracts on the Index, or options on those futures, in lieu of investment directly in the stocks making up the Index. The Fund might do so, for example, in order to increase its investment exposure pending investment of cash in the stocks comprising the Index. Alternatively, the Fund might use futures or options on futures to reduce its investment exposure in situations where it intends to sell a portion of the stocks in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Stock values could decline generally or could under-perform other investments.

- Because the S&P 500 Index includes mainly large U.S. companies, the Fund's investments consist mainly of stocks of large U.S. companies. Returns on investments in stocks of large U.S. companies could trail the returns on investments in stocks of smaller companies.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with

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the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to replicate the performance of the Index may not correlate precisely with the return on the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

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PERFORMANCE INFORMATION.

Bar chart

The bar chart below shows the performance of the Fund's Service Shares during the last several full calendar years. The chart provides some indication of the risks of investing in the Fund's Service Shares by showing changes in the Service Shares' performance from year to year. Please keep in mind that past performance does not necessarily indicate how the Fund's Service Shares will perform in the future. ADDITIONALLY, THE PERFORMANCE INFORMATION PRIOR TO MARCH 10, 2003, THE INCEPTION DATE FOR SERVICE SHARES, IS THAT OF ADMINISTRATIVE SHARES OF THE FUND, WHICH HAS LOWER EXPENSES AND TYPICALLY HIGHER RETURNS THAN THE SERVICE SHARES. THE ADMINISTRATIVE SHARES' INCEPTION DATE WAS APRIL 18, 2001.

STATE STREET EQUITY 500 INDEX FUND
SERVICE SHARES
TOTAL RETURN FOR THE CALENDAR YEAR ENDED DECEMBER 31

(PERFORMANCE GRAPH IN %)

2002                                                                            -22.31
2003                                                                             28.33
2004                                                                             10.51
2005                                                                              4.56

During the period shown in the bar chart, the highest return for a quarter was 15.19% (quarter ended June 30, 2003) and the lowest return for a quarter was (17.37%) (quarter ended September 30, 2002).

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AVERAGE ANNUAL TOTAL RETURN.

The information in the following table gives some indication of the risks of an investment in the Fund's Service Shares by comparing the Fund's Service Shares performance to the performance of the S&P 500 Index over various periods of time.

The Fund's Service Shares' after-tax returns listed below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Additionally, actual after-tax returns depend on an investor's tax situation and may differ from those shown below, and after-tax returns are not relevant to investors who hold their shares through tax-deferred arrangements, such as individual retirement accounts.
ADDITIONALLY, THE FOLLOWING PERFORMANCE INFORMATION PRIOR TO MARCH 10, 2003, THE INCEPTION DATE FOR SERVICE SHARES, IS THAT OF ADMINISTRATIVE SHARES OF THE FUND, WHICH HAS LOWER EXPENSES AND TYPICALLY HIGHER RETURNS THAN THE SERVICE SHARES. THE ADMINISTRATIVE SHARES' INCEPTION DATE WAS APRIL 18, 2001.

                                                   SINCE THE INCEPTION
                                 PAST 1-YEAR        DATE OF THE FUND
                                (PERIOD ENDED          ANNUALIZED
                              DECEMBER 31, 2005)    (APRIL 18, 2001)
                              ------------------   -------------------
State Street Equity 500
  Index Fund Service Shares
     Return Before Taxes....         4.56%                2.40%
     Return After Taxes on
       Distributions........         4.00%                1.97%
     Return After Taxes on
       Distributions and
       Sale of Fund
       Shares...............         2.96%                1.84%
S&P 500 Index*..............         4.91%                2.72%


* The S&P 500 Index is a capitalization-weighted index of 500 widely held stocks recognized by investors to be representative of the stock market in general. The S&P 500 Index is unmanaged and does not reflect the actual cost of investing in the instruments that comprise the index. Additionally, the returns of the S&P 500 Index do not reflect the effect of fees, expenses and taxes.

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FEES AND EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold Service Shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1)................................   0.045%
Distribution (12b-1) Fees.........................    0.25%
Other Expenses....................................    0.05%
                                                     -----
Total Annual Fund Operating Expenses..............   0.345%
                                                     =====


(1) This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

Example: This Example is intended to help you compare the cost of investing in the Fund's Service Shares with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund's Service Shares for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's Service Shares' operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR     3 YEARS    5 YEARS    10 YEARS
-------    -------    -------    --------
  $35       $111       $194        $437

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all common stocks publicly traded in the United States, most of which are listed on the New York Stock Exchange, Inc. (the "NYSE"). Stocks in the S&P 500 Index are weighted according to their market capitalizations (i.e., the number of shares outstanding multiplied by the stock's current price). The companies selected for inclusion in the S&P 500 Index generally have the largest market value within their respective industries. The composition of the S&P 500 Index is determined by Standard & Poor's and is based on

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such factors as the market capitalization and trading activity of each stock and its adequacy as a representation of stocks in a particular industry group, and may be changed from time to time. "Standard & Poor's(R)," "S&P," "S&P 500," "Standard & Poor's 500" and "500" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by the Fund. The Fund is not sponsored, endorsed, sold or promoted by S&P, and S&P makes no representation regarding the advisability of investing in the Fund.

Index Futures Contracts and Related Options. The Fund may buy and sell futures contracts on the Index and options on those futures contracts. An "index futures" contract is a contract to buy or sell units of an index at an agreed price on a specified future date. Depending on the change in value of the Index between the time when the Fund enters into and terminates an index future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts on the Index will not correlate precisely with changes in the value of the Index. In those cases, use of futures contracts and related options might decrease the correlation between the return of the Fund and the return of the Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Index Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security.

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Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Equity 500 Index Fund offers Administrative, Service and Class R Shares. Only the Service Shares of the Fund are discussed in this prospectus.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with

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the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.045% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund is available in the Fund's annual report dated December 31, 2005.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee. Key professionals involved in the day-to-day portfolio management for the Portfolio include the following:

JOHN TUCKER, CFA

Mr. Tucker is a Principal of SSgA and the Adviser. Mr. Tucker joined the firm in 1988 and is a Unit Head for the firm's Exchange Traded Funds Management Team. Mr. Tucker received a BA in Economics from Trinity College and an MS in Finance from Boston College. He is a member of the Boston Security Analysts Society.

MICHAEL FEEHILY, CFA

Mr. Feehily is a Principal of SSgA and the Adviser. Mr. Feehily joined the firm in 1992 and is head of the U.S. Equity Team within the Global Structured Products Team. Mr. Feehily is responsible for overseeing the management of all U.S. equity index funds for State Street Global Advisors. Mr. Feehily holds a Bachelor of Science degree in Finance, Investments, and Economics from Babson College and an MBA in Finance from Bentley College. He is a member of the Boston Security Analysts Society.

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Additional information about the portfolio managers' compensation, other accounts managed by the portfolio managers, and the portfolio managers' ownership of securities in the Fund and the Portfolio is available in the Statement of Additional Information.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is

10

practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity that applies to open an account. For this reason, when you open (or change ownership of ) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect

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and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's Service Shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.25%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

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DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

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FINANCIAL HIGHLIGHTS

The Financial Highlights table is intended to help you understand the Fund's Service Shares financial performance since inception. Certain information reflects financial results for a single share of the Service Shares. The total return in the table represents the rate that an investor would have earned on an investment in the Fund's Service Shares (assuming reinvestment of all dividends and distributions). This information has been audited by Ernst & Young LLP, whose report, along with the Fund's financial statements, are included in the Fund's annual report, which is available upon request. The financial information included in this table should be read in conjunction with the financial statements incorporated by reference in the Statement of Additional Information.

FINANCIAL HIGHLIGHTS FOR A SERVICE SHARE OF BENEFICIAL INTEREST OUTSTANDING

THROUGHOUT THE PERIOD

                                  YEAR       YEAR       PERIOD
                                 ENDED      ENDED        ENDED
                                12/31/05   12/31/04   12/31/03(A)
                                --------   --------   -----------
PER SHARE OPERATING
  PERFORMANCE(b):
NET ASSET VALUE, BEGINNING OF
  PERIOD......................  $ 10.10    $  9.33     $    6.94
                                -------    -------     ---------
INVESTMENT OPERATIONS:
  Net investment income.......     0.16*      0.16*         0.10*
  Net realized and unrealized
     gain on investments......     0.30       0.83          2.38
                                -------    -------     ---------
     Total from investment
       operations.............     0.46       0.99          2.48
                                -------    -------     ---------
LESS DISTRIBUTIONS FROM:
  Net investment income.......    (0.16)     (0.22)        (0.09)
                                -------    -------     ---------
  Net increase in net
     assets...................     0.30       0.77          2.39
                                -------    -------     ---------
NET ASSET VALUE, END OF
  PERIOD......................  $ 10.40    $ 10.10     $    9.33
                                =======    =======     =========
TOTAL RETURN(c)...............     4.56%     10.51%        35.71%
                                =======    =======     =========
RATIOS AND SUPPLEMENTARY DATA:
  Net Assets, End of Period
     (000s)...................  $39,086    $12,964     $  84,244
  Ratios to average net
     assets:
     Operating expenses.......    0.345%     0.345%        0.345%(d)
     Net investment income....     1.56%      1.67%         1.45%(d)
  Portfolio turnover rate.....        8%         9%           12%


(a) Service Shares commenced operations on March 10, 2003.

(b) The per share amounts and percentages include the Fund's proportionate share of income and expenses of the State Street Equity 500 Index Portfolio.

(c) Total return is calculated assuming a purchase of shares at net asset value on the first day and a sale at net asset value on the last day of each period reported. Distributions are assumed, for the purpose of this calculation, to be reinvested at net asset value per share on the respective payment dates. Total return for periods of less than one year is not annualized. Results represent past performance and are not indicative of future results.

(d) Annualized.

* Net investment income per share calculated using the average shares method.

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For more information about STATE STREET EQUITY 500 INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments is available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports are available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-551-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET EQUITY 500 INDEX FUND
CLASS R SHARES


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Equity 500 Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Standard & Poor's 500(R) Composite Stock Price Index (the "S&P 500 Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the S&P 500 Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund is not managed according to traditional methods of "active" investment management, which involve the buying and selling of securities based upon economic, financial and market analysis and investment judgment. Instead, the Fund, using a "passive" or "indexing" investment approach, attempts to match, before expenses, the performance of the S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all stocks publicly traded in the United States. The Adviser seeks a correlation of 0.95 or better

1

between the Fund's performance and the performance of the Index (1.00 would represent perfect correlation).

The Fund intends to invest (either on its own or as part of a master-feeder structure) in all 500 stocks comprising the Index in proportion to their weightings in the Index. However, under various circumstances, it may not be possible or practicable to purchase all 500 stocks in those weightings. In those circumstances, the Fund may purchase a sample of the stocks in the Index in proportions expected by the Adviser to match generally the performance of the Index as a whole. In addition, from time to time stocks are added to or removed from the Index. The Fund may sell stocks that are represented in the Index, or purchase stocks that are not yet represented in the Index, in anticipation of their removal from or addition to the Index. In no event will the Fund invest less than 80% of its total assets in stocks in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

In addition, the Fund may at times purchase or sell futures contracts on the Index, or options on those futures, in lieu of investment directly in the stocks making up the Index. The Fund might do so, for example, in order to increase its investment exposure pending investment of cash in the stocks comprising the Index. Alternatively, the Fund might use futures or options on futures to reduce its investment exposure in situations where it intends to sell a portion of the stocks in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Stock values could decline generally or could under-perform other investments.

- Because the S&P 500 Index includes mainly large U.S. companies, the Fund's investments consist mainly of stocks of large U.S. companies. Returns on investments in stocks of large U.S. companies could trail the returns on investments in stocks of smaller companies.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with

2

the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to replicate the performance of the Index may not correlate precisely with the return on the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

3

PERFORMANCE INFORMATION.

Bar chart

The bar chart below shows the performance of the Fund's Class R Shares during the last several full calendar years. The chart provides some indication of the risks of investing in the Fund's Class R Shares by showing changes in the Class R Shares' performance from year to year. Please keep in mind that past performance does not necessarily indicate how the Fund's Class R Shares will perform in the future. ADDITIONALLY, THE PERFORMANCE INFORMATION PRIOR TO JUNE 7, 2005, THE INCEPTION DATE FOR CLASS R SHARES, IS THAT OF THE ADMINISTRATIVE SHARES OF THE FUND, WHICH HAS LOWER EXPENSES AND TYPICALLY HIGHER RETURNS THAN THE CLASS R SHARES. THE PRIMARY DIFFERENCE IN EXPENSES IS THE LOWER DISTRIBUTION (12B-1) FEE OF 0.15% FOR ADMINISTRATIVE SHARES COMPARED TO 0.60% FOR CLASS R SHARES ON AN ANNUAL BASIS. THE ADMINISTRATIVE SHARES' INCEPTION DATE WAS APRIL 18, 2001.

STATE STREET EQUITY 500 INDEX FUND
CLASS R SHARES
TOTAL RETURN FOR THE CALENDAR YEAR ENDED DECEMBER 31

[STATE STREET EQUITY 500 INDEX FUND BAR CHART]:

2002                                                                            -22.31
2003                                                                             28.37
2004                                                                             10.63
2005                                                                              4.24

During the period shown in the bar chart, the highest return for a quarter was 15.19% (quarter ended June 30, 2003) and the lowest return for a quarter was (17.37%) (quarter ended September 30, 2002).

AVERAGE ANNUAL TOTAL RETURN

The information in the following table gives some indication of the risks of an investment in the Fund's Class R Shares by comparing the Class R

4

Shares' performance to the performance of the S&P 500 Index over various periods of time.

The Fund's Class R Shares' after-tax returns listed below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Additionally, actual after-tax returns depend on an investor's tax situation and may differ from those shown below, and after-tax returns are not relevant to investors who hold their shares through tax-deferred arrangements, such as individual retirement accounts.
ADDITIONALLY, THE PERFORMANCE INFORMATION PRIOR TO JUNE 7, 2005, THE INCEPTION DATE FOR CLASS R SHARES, IS THAT OF THE ADMINISTRATIVE SHARES OF THE FUND, WHICH HAS LOWER EXPENSES AND TYPICALLY HIGHER RETURNS THAN THE CLASS R SHARES. THE PRIMARY DIFFERENCE IN EXPENSES IS THE LOWER DISTRIBUTION (12B-1) FEE OF 0.15% FOR ADMINISTRATIVE SHARES COMPARED TO 0.60% FOR CLASS R SHARES ON AN ANNUAL BASIS. THE ADMINISTRATIVE SHARES' INCEPTION DATE WAS APRIL 18, 2001.

                                                   SINCE THE INCEPTION
                                 PAST 1-YEAR        DATE OF THE FUND
                                (PERIOD ENDED          ANNUALIZED
                              DECEMBER 31, 2005)    (APRIL 18, 2001)
                              ------------------   -------------------
State Street Equity 500
  Index Fund Class R Shares
     Return Before Taxes....         4.24%                2.36%
     Return After Taxes on
       Distributions........         3.77%                1.95%
     Return After Taxes on
       Distributions and
       Sale of Fund
       Shares...............         2.75%                1.81%
S&P 500 Index*..............         4.91%                2.72%


* The S&P 500 Index is a capitalization-weighted index of 500 widely held stocks recognized by investors to be representative of the stock market in general. The S&P 500 Index is unmanaged and does not reflect the actual cost of investing in the instruments that comprise the index. Additionally, the returns of the S&P 500 Index do not reflect the effect of fees, expenses and taxes.

FEES AND EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold Class R Shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

5

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1).................................  0.045%
Distribution (12b-1) Fees..........................   0.60%
Other Expenses.....................................   0.05%
                                                     -----
Total Annual Fund Operating Expenses...............  0.695%
                                                     =====


1 This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

Example: This Example is intended to help you compare the cost of investing in the Fund's Class R Shares with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund's Class R Shares for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's Class R Shares' operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR   3 YEARS   5 YEARS   10 YEARS
------   -------   -------   --------
 $71      $222      $387       $865

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The S&P 500 Index. The S&P 500 Index is a well-known stock market index that includes common stocks of 500 companies from several industrial sectors representing a significant portion of the market value of all common stocks publicly traded in the United States, most of which are listed on the New York Stock Exchange, Inc. (the "NYSE"). Stocks in the S&P 500 Index are weighted according to their market capitalizations (i.e., the number of shares outstanding multiplied by the stock's current price). The companies selected for inclusion in the S&P 500 Index generally have the largest market value within their respective industries. The composition of the S&P 500 Index is determined by Standard & Poor's and is based on such factors as the market capitalization and trading activity of each stock and its adequacy as a representation of stocks in a particular industry group, and may be changed from time to time. "Standard & Poor's(R)," "S&P," "S&P 500," "Standard & Poor's 500" and "500" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by the Fund. The Fund is not sponsored, endorsed, sold or promoted by S&P, and S&P makes no representation regarding the advisability of investing in the Fund.

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Index Futures Contracts and Related Options. The Fund may buy and sell futures contracts on the Index and options on those futures contracts. An "index futures" contract is a contract to buy or sell units of an index at an agreed price on a specified future date. Depending on the change in value of the Index between the time when the Fund enters into and terminates an index future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts on the Index will not correlate precisely with changes in the value of the Index. In those cases, use of futures contracts and related options might decrease the correlation between the return of the Fund and the return of the Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Index Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security. Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

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Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Equity 500 Index Fund offers three classes of shares: Administrative Shares, Service Shares and Class R Shares. Only the Class R Shares of the Fund are discussed in this prospectus.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.045% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The

8

Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund is available in the Fund's annual report dated December 31, 2005.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee. Key professionals involved in the day-to-day portfolio management for the Portfolio include the following:

JOHN TUCKER, CFA

Mr. Tucker is a Principal of SSgA and the Adviser. Mr. Tucker joined the firm in 1988 and is a Unit Head for the firm's Exchange Traded Funds Management Team. Mr. Tucker received a BA in Economics from Trinity College and an MS in Finance from Boston College. He is a member of the Boston Security Analysts Society.

MICHAEL FEEHILY, CFA

Mr. Feehily is a Principal of SSgA and the Adviser. Mr. Feehily joined the firm in 1992 and is head of the U.S. Equity Team within the Global Structured Products Team. Mr. Feehily is responsible for overseeing the management of all U.S. equity index funds for State Street Global Advisors. Mr. Feehily holds a Bachelor of Science degree in Finance, Investments, and Economics from Babson College and an MBA in Finance from Bentley College. He is a member of the Boston Security Analysts Society.

Additional information about the portfolio managers' compensation, other accounts managed by the portfolio managers, and the portfolio managers' ownership of securities in the Fund and the Portfolio is available in the Statement of Additional Information.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

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The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity that applies

10

to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through

11

a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's Class R Shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.60%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

12

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

13

FINANCIAL HIGHLIGHTS

The Financial Highlights table is intended to help you understand the Fund's Class R Shares financial performance since inception. Certain information reflects financial results for a single share of the Class R Shares. The total return in the table represents the rate that an investor would have earned on an investment in the Fund's Class R Shares (assuming reinvestment of all dividends and distributions). This information has been audited by Ernst & Young LLP, whose report, along with the Fund's financial statements, are included in the Fund's annual report, which is available upon request. The financial information included in this table should be read in conjunction with the financial statements incorporated by reference in the Statement of Additional Information.

FINANCIAL HIGHLIGHTS FOR A CLASS R SHARE OF BENEFICIAL INTEREST OUTSTANDING

THROUGHOUT THE PERIOD

                                                           PERIOD
                                                            ENDED
                                                         12/31/05(A)
                                                         -----------
PER SHARE OPERATING PERFORMANCE(b):
NET ASSET VALUE, BEGINNING OF PERIOD...................    $ 9.98
                                                           ------
INVESTMENT OPERATIONS:
  Net investment income................................      0.08*
  Net realized and unrealized gain on investments......      0.41
                                                           ------
    Total from investment operations...................      0.49
                                                           ------
LESS DISTRIBUTIONS FROM:
  Net investment income................................     (0.07)
                                                           ------
  Net increase in net assets...........................      0.42
                                                           ------
NET ASSET VALUE, END OF PERIOD.........................    $10.40
                                                           ======
TOTAL RETURN(c)........................................      4.92%
                                                           ======
RATIOS AND SUPPLEMENTARY DATA:
  Net Assets, End of Period (000s).....................    $  105
  Ratios to average net assets:
    Operating expenses.................................     0.650%(d)
    Net investment income..............................      1.37%(d)
  Portfolio turnover rate..............................         8%


(a) Class R Shares commenced operations on June 7, 2005.

(b) The per share amounts and percentages include the Fund's proportionate share of income and expenses of the State Street Equity 500 Index Portfolio.

(c) Total return is calculated assuming a purchase of shares at net asset value on the first day and a sale at net asset value on the last day of each period reported. Distributions are assumed, for the purpose of this calculation, to be reinvested at net asset value per share on the respective payment dates. Total return for periods of less than one year is not annualized. Results represent past performance and are not indicative of future results.

(d) Annualized.

* Net investment income per share calculated using the average shares method.

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For more information about STATE STREET EQUITY 500 INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments is available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports are available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083 or the customer service center at the telephone number shown in the accompanying contract prospectus, if applicable. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-551-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET INSTITUTIONAL
LIQUID RESERVES FUND


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

AN INVESTMENT IN THE STATE STREET INSTITUTIONAL LIQUID RESERVES FUND (THE "FUND") IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

The Fund seeks to maximize current income, to the extent consistent with the preservation of capital and liquidity and the maintenance of a stable $1.00 per share net asset value, by investing in dollar denominated securities. There is no guarantee the Fund will be able to maintain a stable net asset value per share.


INTRODUCTION

The State Street Institutional Liquid Reserves Fund (the "Fund") is a mutual fund that seeks to maximize current income, to the extent consistent with the preservation of capital and liquidity and the maintenance of a stable $1.00 per share net asset value ("NAV"), by investing in dollar denominated securities. The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in the State Street Money Market Portfolio (the "Portfolio") of State Street Master Funds, which has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and strategies of the Fund below, you should assume that the investment objective and strategies of the Portfolio are the same in all material respects as those of the Fund and that, so long as the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio.

The Fund attempts to meet its investment objective by investing in high- quality money market instruments. Such instruments include: (1) U.S. Treasury bills, notes and bonds; (2) other obligations issued or guaranteed as to interest and principal by the U.S. government, its agencies, or instrumentalities; (3) instruments of U.S. and foreign banks, including certificates of deposit, bankers' acceptances and time deposits, including Eurodollar Certificates of Deposit ("ECDs"), Eurodollar Time Deposits ("ETDs") and Yankee Certificates of Deposit ("YCDs"); (4) commercial paper of U.S. and foreign companies; (5) asset-backed securities; (6) corporate obligations of U.S. and foreign companies; (7) variable and floating rate notes; and (8) repurchase agreements.

Normally, the Fund intends to invest more than 25% of its total assets in bank obligations.

Quality of Securities. The Fund will limit its portfolio investments to those United States dollar-denominated instruments which at the time of

1

acquisition the Adviser determines present minimal credit risk and which qualify as "eligible" securities under the SEC rules applicable to money market mutual funds. In general, eligible securities include securities that: (1) are rated in one of the two highest short-term categories by at least two nationally recognized statistical rating organizations ("NRSRO"); (2) are rated in one of the two highest short-term categories by one NRSRO, if only one NRSRO has rated the security; or (3) if unrated, are of comparable quality to the rated security described above, as determined by the Adviser in accordance with procedures established by the Board of Trustees.

Portfolio Maturity. A money market fund must limit its investments to securities with remaining maturities determined in accordance with applicable SEC regulations and must maintain a dollar-weighted average maturity of 90 days or less. The Fund will normally hold portfolio instruments to maturity, but may dispose of them prior to maturity if the Adviser finds it advantageous or necessary. Investing in short-term money market instruments will result in high portfolio turnover. Since the cost of these transactions is small, high turnover is not expected to adversely affect the Fund's price or yield.

The Adviser bases its decisions on the relative attractiveness of different money market investments which can vary depending on the general level of interest rates as well as supply/demand imbalances in the market. There are risks associated with these instruments, which are summarized below.

PRINCIPAL RISKS OF INVESTING IN THE FUND

- Money Market Risk. The Fund may not be able to maintain a NAV per share of $1.00 at all times. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

- Interest Rate Risk. During periods of rising interest rates, the Fund's yield may tend to be lower than prevailing market rates; in periods of falling interest rates, the Fund's yield may tend to be higher.

- Credit/Default Risk. An issuer of fixed-income securities held by the Fund may default on its obligation to pay interest and repay principal when due. There is also a risk that the credit rating of one or more of the securities will be downgraded. Generally, lower rated bonds have higher credit risks.

2

- U.S. Government Securities Risk. Although securities issued directly by the U.S. government are guaranteed by the U.S. Treasury, other securities issued by an agency or instrumentality of the U.S. government may not be. No assurance can be given that the U.S. government would provide financial support to its agencies and instrumentalities if not required to do so by law.

- Foreign Risk. The Fund may invest in the U.S. dollar denominated instruments of foreign issuers. Foreign issuers can pose greater risks than U.S. issuers. Foreign securities could lose value as a result of political, financial and economic events in foreign countries, less stringent foreign securities regulations and accounting and disclosure standards, or other factors.

- Banking Industry Risk. Because the Fund may concentrate more than 25% of its assets in bank obligations, adverse developments in the banking industry may have a greater effect on the Fund than on a mutual fund that invests more broadly. For instance, if the banking industry suffers a setback, the Fund may perform worse than if the Fund were more diversified across numerous industries. Banks may be particularly sensitive to certain economic factors such as interest rate changes, adverse developments in the real estate market, fiscal and monetary policy and general economic cycles.

- Repurchase Agreement Risk. A repurchase agreement allows the Fund to buy securities with the understanding that the seller will buy them back with interest at a later date. If the seller is unable to honor its commitment to repurchase the securities, the Fund could lose money.

- Management Strategy Risk. A strategy used by the Adviser may fail to produce the intended results.

- Fixed-Income Securities Risk. The risks of fixed-income securities include, but are not limited to, interest rate risk, credit risk and call/ extension risk. Credit risk involves the risk that the issuer could default on its obligations, and the Fund will not recover its investment. Call risk and extension risk are normally present in adjustable rate mortgage loans, mortgage-backed securities and asset-backed securities.

- Liquidity Risk. The Fund may be unable to pay redemption proceeds within the time period stated in this prospectus because of unusual market conditions, an unusually high volume of redemption requests, or other reasons.

3

PERFORMANCE INFORMATION.

The bar chart and table below show the performance of the Fund during the last full calender year. The table below also shows the performance of the Fund over various periods of time since its inception on August 12, 2004. Please keep in mind that past performance does not necessarily indicate how the Fund will perform in the future.

STATE STREET INSTITUTIONAL LIQUID RESERVES FUND
TOTAL RETURN FOR THE CALENDAR YEAR ENDED DECEMBER 31*

(STATE STREET EQUITY 500 INDEX FUND BAR CHART)

2005                                                                             3.19

During the period shown in the bar chart, the highest return for a quarter was 1.02% (quarter ended December 31, 2005) and the lowest return for a quarter was 0.57% (quarter ended March 31, 2005).

AVERAGE ANNUAL TOTAL RETURN*

                                                   SINCE THE INCEPTION
                                 PAST 1-YEAR        DATE OF THE FUND
                                (PERIOD ENDED          ANNUALIZED
                              DECEMBER 31, 2005)    (AUGUST 12, 2004)
                              ------------------   -------------------
State Street Institutional
  Liquid Reserves Fund......          3.19%                2.78%


* Certain expenses incurred by the Fund were reimbursed during the period. Without the reimbursement of some expenses, total returns would be lower.

Please call (877) 521-4083 for the Fund's current 7-day yield.

4

FEES AND EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. As a shareholder in the Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees*..................................    0.10%
Distribution (12b-1) Fees.........................    0.05%
Other Expenses....................................    0.02%
                                                     -----
Total Annual Fund Operating Expenses..............    0.17%
                                                     =====
Less Waivers and Reimbursement**..................   (0.02)%
                                                     -----
Net Expenses**....................................    0.15%
                                                     =====


* This fee is the investment advisory fee paid by the Portfolio to the Adviser and represents the total annual net operating expenses of the Portfolio. The Adviser has contractually agreed to waive fees and/or reimburse expenses of the Portfolio to keep the total annual operating expenses of the Portfolio at 0.10% through November 1, 2007. Without the effects of such contractual limitation, the total annual operating expenses of the Portfolio were 0.14% for the last fiscal year.

** The Adviser has contractually agreed to cap the total operating expenses (not including the pass-through expenses of the Portfolio) at 0.05% (on an annualized basis) of the Fund's average daily net assets until November 1, 2007. In addition, the Adviser has voluntarily agreed to cap the total operating expenses (not including the pass-thru expenses of the Portfolio) at 0.02% (on an annualized basis), reducing total net operating expenses from 0.15% to 0.12%. This voluntary expense limitation may be revised or canceled at any time without notice.

Example: This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, the Net Expenses of the Fund shown in the table above apply through the first year of investment and after that date the Total Annual Fund Operating Expenses of the Fund shown in the table above apply. Although your actual

5

costs may be higher or lower, based on these assumptions yours costs would be:

1 YEAR    3 YEARS   5 YEARS   10 YEARS
-------   -------   -------   --------
  $15       $53       $94       $215

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.10% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

6

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund is available in the Fund's annual report dated December 31, 2005.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator and Custodian. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator and custodian.

The Transfer and Dividend Disbursing Agent. ALPS Mutual Funds Services, Inc. is the transfer and dividend disbursing agent.

ADDITIONAL INFORMATION ABOUT THE FUND'S OBJECTIVES, INVESTMENT STRATEGIES AND RISKS

The investment objective of the Fund as stated above may be changed without shareholder approval. The investment policies described below reflect the Fund's current practices. In addition to the principal risks explained above, other risks are explained in some of the descriptions of the investment policies below:

Variable and Floating Rate Securities. The Fund may purchase variable and floating rate securities which are instruments issued or guaranteed by entities such as the: (1) U.S. government, or an agency or instrumentality thereof, (2) corporations, (3) financial institutions or (4) insurance companies. The interest rate on a variable rate security typically adjusts automatically on fixed dates or after specified periods of time. The interest rate on a floating rate security typically adjusts automatically in response to specified interest rate changes. Interest rates on these securities are ordinarily tied to, and are a percentage of, a widely recognized interest rate, such as the yield on 90-day U.S. Treasury bills or the prime rate of a specified bank.

Asset-Backed Securities. Asset-backed securities are debt securities whose principal and interest payments are collateralized by pools of assets such as mortgages, auto loans, credit card receivables, leases, installment contracts and personal property. The securities are sponsored by entities such as government agencies, banks, financial companies and commercial or industrial companies. Payments of principal and interest are passed through to holders of the securities and may be supported by some form of credit enhancement, such as over-collateralization, a letter of credit, surety bond, limited guarantee by another entity or by priority to certain of the bor-

7

rower's other securities. The degree of credit enhancement varies, generally applying only until exhausted and covering only a fraction of the security's par value. If the credit enhancement of an asset-backed security held by the Fund has been exhausted, and if any required payments of principal and interest are not made with respect to the underlying loans, the Fund may experience loss or delay in receiving payment and a decrease in the value of the security.

- Prepayment Risk -- Asset-backed securities are often subject to more rapid prepayment than their stated maturity date would indicate as a result of the pass-through of prepayments of principal on the underlying loans. During periods of declining interest rates, prepayment of loans underlying asset-backed securities can be expected to accelerate. The Fund's ability to maintain positions in such securities will be affected by reductions in the principal amount of such securities resulting from prepayments, and its ability to reinvest the returns of principal at comparable yields is subject to generally prevailing interest rates at that time. To the extent that the Fund invests in asset-backed securities, the values of those securities will vary with changes in market interest rates generally and the differences in yields among various kinds of asset-backed securities.

- Other Risks Associated with Asset-Backed Securities -- Certain asset-backed securities have special risks resulting from the fact that the underlying loans are not collateralized by real estate or comparable assets. For instance, credit card receivables are generally unsecured and the debtors on such receivables are protected by a number of state and federal consumer credit law. In some cases, these laws give debtors the right to set-off certain amounts owed on the credit cards, reducing the balance due. Automobile receivables generally are secured by automobiles. Most issuers of automobile receivables permit the loan servicers to retain possession of the underlying obligations. If the servicer were to sell these obligations to another party, there is a risk that the purchaser would acquire an interest superior to that of the holders of the asset-backed securities. In addition, because of the large number of vehicles involved in a typical issuance and technical requirements under state laws, the trustee for the holders of the automobile receivables may not have a proper security interest in the underlying automobiles. Therefore, there is the possibility that, in some cases, recoveries on repossessed automobiles may not be available to support payments on these securities.

8

U.S. Government Securities. U.S. government securities include U.S. Treasury bills, notes, bonds and other obligations issued or guaranteed as to interest and principal by the U.S. government, its agencies or instrumentalities. Obligations issued or guaranteed as to interest and principal by the U.S. government, its agencies or instrumentalities include securities that are supported by the full faith and credit of the United States Treasury, securities that are supported by the right of the issuer to borrow from the United States Treasury, discretionary authority of the U.S. government agency or instrumentality, and securities supported solely by the creditworthiness of the issuer.

Eurodollar Certificates of Deposit (ECDs), Eurodollar Time Deposits (ETDs) and Yankee Certificates of Deposit (YCDs). ECDs are U.S. dollar denominated certificates of deposit issued by a bank outside of the United States. ETDs are U.S. dollar denominated deposits in foreign branches of U.S. banks and foreign banks. YCDs are U.S. dollar denominated certificates of deposit issued by U.S. branches of foreign banks. Different risks than those associated with the obligations of domestic banks may exist for ECDs, ETDs and YCDs. The banks issuing these instruments, or their domestic or foreign branches, are not necessarily subject to the same regulatory requirements that apply to U.S. banks operating in the United States. Foreign laws and accounting standards typically are not as strict as they are in the U.S. so there may be fewer restrictions on loan limitations, less frequent examinations and less stringent requirements regarding reserve accounting, auditing, recordkeeping and public reporting requirements.

Section 4(2) Commercial Paper and Rule 144A Securities. The Fund may invest in commercial paper issued in reliance on the private placement exemption from registration afforded by Section 4(2) of the Securities Act of 1933, as amended ("1933 Act"). This commercial paper is commonly called "Section 4(2) paper." The Fund may also invest in securities that may be offered and sold only to "qualified institutional buyers" under Rule 144A of the 1933 Act ("Rule 144A securities").

Section 4(2) paper is sold to institutional investors who must agree to purchase the paper for investment and not with a view to public distribution. Any resale by the purchaser must be in an exempt transaction. Section 4(2) paper normally is resold to other institutional investors like the Fund through or with the assistance of the issuer or investment dealers that make a market in
Section 4(2) paper. As a result it suffers from a liquidity risk, the risk that the securities may be difficult to value because of the absence of an active market and may be sold only after considerable expense

9

and delay, if at all. Rule 144A securities generally must be sold only to other qualified institutional buyers.

Section 4(2) paper and Rule 144A securities will not be subject to the Fund's 10% limitation on illiquid securities if the Adviser (pursuant to guidelines adopted by the Board) determines that a liquid trading market exists. There can be no assurance that a liquid trading market will exist at any time for either
Section 4(2) paper or Rule 144A securities. The Fund's Statement of Additional Information ("SAI") addresses the limitation on illiquid securities.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund determines the price per share (or NAV) once each business day at 4:00 p.m. Eastern time (ET) or the close of the New York Stock Exchange (the "NYSE"), whichever is earlier. Pricing does not occur on NYSE holidays. A business day is one on which the NYSE is open for regular trading. The Federal Reserve is closed on certain holidays on which the NYSE is open. These holidays are Columbus Day and Veteran's Day. On these holidays, you will not be able to purchase shares by wiring Federal Funds because the Federal Funds wiring does not occur on these holidays. Payment for Fund shares must be in Federal Funds (or converted to Federal Funds by the Transfer Agent) by 4 p.m. ET before a purchase order can be accepted.

The price per share for the Fund is computed by adding the value of all securities and other assets of the Fund, deducting accrued liabilities, dividing by the number of shares outstanding and rounding to the nearest cent.

The Fund seeks to maintain a $1.00 per share NAV and, accordingly, uses the amortized cost valuation method to value its portfolio instruments. The amortized cost valuation method initially prices an instrument at its cost and thereafter assumes a constant amortization to maturity of any discount or premium, regardless of the impact of fluctuating interest rates on the market value of the instrument.

Purchasing Shares. Investors pay no sales load to invest in the Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment, except in relation to maintaining certain minimum account balances (See "Redeeming Shares" below). The Fund intends to be as fully invested as is practicable; therefore, investments must be made in Federal

10

Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank). The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

HOW TO PURCHASE SHARES

BY MAIL:

An initial investment in the Fund must be preceded or accompanied by a completed, signed Institutional Account Application Form, sent to:

State Street Institutional Liquid Reserves Fund 1625 Broadway, Suite 2200
Denver, CO 80218

BY TELEPHONE/FAX:

An initial investment in the Fund must be preceded or accompanied by a completed, signed Institutional Account Application Form, faxed to (303) 825-2575. Call the Fund at (303) 623-2577 between the hours of 8:30 a.m. ET and 5:00 p.m. ET to:

- confirm receipt of the faxed Institutional Account Application Form (initial purchases only),

- request your new account number (initial purchases only),

- confirm the amount being wired and wiring bank,

- confirm the name and number of the contact person in connection with the order at the wiring bank, and

- receive a confirmation number for your purchase order (your trade is not effective until you have received a confirmation number from the Fund),

For your initial investment, send the original, signed Institutional Account Application Form to the address above.

WIRE INSTRUCTIONS:

Instruct your bank to transfer money by Federal Funds wire to:

State Street Bank & Trust Co
225 Franklin Street
Boston, MA 02171

ABA# 011000028

DDA# 0015-755-2
Account Name: State Street Institutional Liquid Reserves Fund Ref: Shareholder Account #
Ref: Shareholder Name

11

On Columbus Day and Veteran's Day, you will not be able to purchase shares by wiring Federal Funds because the Federal Funds wiring does not occur on those days. Payment for Fund shares must be in Federal Funds (or converted to Federal Funds by the Transfer Agent) by 4 p.m. ET before a purchase order can be accepted.

You will not be able to redeem shares from the account until the original Application has been received. The Fund and its agents are not responsible for transfer errors by the sending or receiving bank and will not be liable for any loss incurred due to a wire transfer not having been received.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity who applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. Redemption orders are processed at the NAV next determined after the Fund receives your order in good form. If the Fund receives your redemption order prior to 4 p.m. ET on a business day, the Fund may send payment for your redeemed shares on that day. Otherwise, the Fund will generally send payment for your redeemed shares on the next business day. The Fund reserves the right to pay for redeemed shares within seven days after receiving your redemption order if, in the judgment of the Adviser, an earlier payment could adversely affect the Fund. The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

A request for a partial redemption by an investor whose account balance is below the minimum amount or a request for partial redemption by an investor that would bring the account below the minimum amount may be

12

treated as a request for a complete redemption of the account. These minimums may be different for investments made through certain financial intermediaries as determined by their policies and may be waived in the Adviser's discretion. The Fund reserves the right to modify its minimum account requirements at any time with or without prior notice. The Fund also reserves the right to involuntarily redeem an investor's account if the investor's account balance falls below the applicable minimum amount due to transaction activity.

HOW TO REDEEM SHARES

BY MAIL

Send a signed letter to:
State Street Institutional Liquid Reserves Fund 1625 Broadway, Suite 2200
Denver, CO 80218

The letter should include information necessary to process your request as described below. The Fund may require a signature guarantee in certain circumstances. See "Signature Guarantees" below.

BY TELEPHONE BETWEEN THE HOURS OF 8:30 A.M. AND 5 P.M. EASTERN TIME

Please Call (303) 623-2577

The Fund will need the following information to process your redemption request:

- name(s) of account owners;

- account number(s);

- the name of the Fund;

- your daytime telephone number; and

- the dollar amount, percentage or number of shares being redeemed.

On any day that the Fund calculates its NAV earlier than normal, the Fund reserves the right to adjust the times noted above for purchasing and redeeming shares.

Signature Guarantees. Certain redemption requests must include a signature guarantee for each registered account owner if any of the following apply:

- Your account address has changed within the last 10 business days.

- A wire is being made payable to someone other than the account owner.

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- Redemption proceeds are being transferred to an account with a different registration.

- A wire is being sent to a financial institution other than the one that has been established on your Fund account.

- Other unusual situations as determined by the Fund's transfer agent.

The Fund reserves the right to waive signature guarantee requirements, require a signature guarantee under other circumstances or reject or delay a redemption if the signature guarantee is not in good form. Signature guarantees may be provided by an eligible financial institution such as a commercial bank, a NASD member firm such as a stock broker, a savings association or a national securities exchange. A notary public cannot provide a signature guarantee. The Fund reserves the right to reject a signature guarantee if it is not provided by a STAMP 2000 Medallion guarantor.

About Telephone and Internet Transactions. You may choose to access your account 24 hours a day and conduct transactions in the Fund via its web interface secure account access. All shareholder transaction orders via the Internet are processed at the NAV next determined after your transaction order is received in good order. To learn more and sign up for online account access, please see the website at www.sttfunds.com. Telephone and Internet transactions are extremely convenient but are not free from risk. Neither the Fund nor the Fund's agents will be responsible for any losses resulting from unauthorized telephone or Internet transactions if reasonable security procedures are followed. For transactions over the Internet, we recommend the use of a secure internet browser. In addition, you are responsible for: (i) verifying the accuracy of all data and information transmitted via the Internet or by telephone, (ii) verifying the accuracy of your account statements immediately upon receipt, and (iii) promptly notifying the Fund of any errors or inaccuracies including, without limitation, any errors or inaccuracies relating to shareholder data or information transmitted via the Internet or by telephone. During periods of heavy market activity or other times, it may be difficult to reach the Fund by telephone or to transact business over the Internet. Technological irregularities may also make the use of the Internet slow or unavailable at times. If you are unable to reach us by telephone or unable to transact business over the Internet, consider sending written instructions.

The Fund may terminate the receipt of redemption or exchange orders by telephone or the Internet at any time, in which case you may redeem or exchange shares by other means.

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Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser, State Street or their agents will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.05%. Because these fees are paid out of the Fund's

15

assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

The Fund intends to declare dividends on shares from net investment income daily and pay them as of the last business day of each month. Distributions from capital gains, if any, will be made annually in December.

Dividends from net investment income and distributions of net short-term capital gains are taxable to you as ordinary income under federal income tax laws whether paid in cash or in additional shares.

Any gains resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

16

FINANCIAL HIGHLIGHTS

The Financial Highlights table is intended to help you understand the Fund's financial performance since inception. Certain information reflects financial results for a single share of the Fund. The total return in the table represents the rate that an investor would have earned on an investment in the Fund (assuming reinvestment of all dividends and distributions). This information has been audited by Ernst & Young LLP, whose report, along with the Fund's financial statements, are included in the Fund's annual report, which is available upon request. The financial information included in this table should be read in conjunction with the financial statements incorporated by reference in the Statement of Additional Information.

FINANCIAL HIGHLIGHTS -- SELECTED DATA FOR A SHARE OF BENEFICIAL INTEREST

OUTSTANDING THROUGHOUT THE PERIOD

                                             YEAR ENDED   PERIOD ENDED
                                             12/31/2005    12/31/04*
                                             ----------   ------------
PER SHARE OPERATING PERFORMANCE(a):
Net Asset Value, Beginning of Period.......  $   1.0000     $ 1.0000
                                             ----------     --------
INVESTMENT OPERATIONS:
  Net investment income....................      0.0315       0.0066
                                             ----------     --------
  Gain (loss) on investments...............      0.0000**         --
                                             ----------     --------
    Total from investment operations.......      0.0315       0.0067
                                             ----------     --------
LESS DISTRIBUTIONS FROM:
  Net investment income....................    (0.0315)      (0.0066)
                                             ----------     --------
  Net increase (decrease) in net assets....          --           --
                                             ----------     --------
NET ASSET VALUE, END OF PERIOD.............  $   1.0000     $ 1.0000
                                             ==========     ========
TOTAL RETURN(b)............................        3.19%        0.66%
RATIOS AND SUPPLEMENTAL DATA:
  Net assets, end of period (in
    thousands).............................  $1,639,747     $381,638
  Ratio of gross expenses to average net
    assets.................................        0.17%        0.23%***
  Ratio of net expenses to average net
    assets.................................        0.14%        0.15%***
  Ratio of net investment income to average
    net assets.............................        3.30%        1.67%***
  Voluntary expense reimbursement (c)......        0.01%          --


* The Fund commenced operations on August 12, 2004. ** Amount is less than $0.0001. *** Annualized.
(a) The per share amounts and percentages include the Fund's proportionate share of income and expenses of the State Street Money Market Portfolio.
(b) Total return is calculated assuming a purchase of shares at net asset value on the first day and a sale at net asset value on the last day of each period reported. Distributions are assumed, for the purpose of this calculation, to be reinvested at net asset value per share on the respective payment dates. Total return for periods of less than one year is not annualized. Results represent past performance and are not indicative of future results.
(c) This voluntary expense reimbursement is reflected in both the net expense and the net income ratios shown above.

17

For more information about STATE STREET INSTITUTIONAL LIQUID RESERVES FUND:

The Fund's SAI includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments is available in the Fund's annual and semi-annual reports to shareholders.

The SAI and the Fund's annual and semi-annual reports are available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund's Internet website, primarily intended for account access, does not contain such information.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-551-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET EQUITY 400 INDEX FUND


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Equity 400 Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Standard & Poor's MidCap 400(R)Composite Stock Price Index (the "S&P 400 Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the S&P 400 Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of the State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund is not managed according to traditional methods of "active" investment management, which involve the buying and selling of securities based upon economic, financial and market analysis and investment judgment. Instead, the Fund, using a "passive" or "indexing" investment approach, attempts to match, before expenses, the performance of the S&P 400 Index. The S&P 400 Index is a well-known stock market index that includes common stocks of 400 mid-sized companies from several industrial sectors representing a significant portion of the market value of all stocks publicly traded in the United States (for a discussion of how the securities in

1

the S&P 400 Index are selected, see "Other Investment Considerations and Risks - The S&P 400 Index," below). The Adviser seeks a correlation of 0.95 or better between the Fund's performance and the performance of the Index (1.00 would represent perfect correlation).

The Fund intends to invest (either on its own or as part of a master-feeder structure) in all of the stocks comprising the Index in proportion to their weightings in the Index. However, under various circumstances, it may not be possible or practicable to purchase all 400 stocks in those weightings. In those circumstances, the Fund may purchase a sample of the stocks in the Index in proportions expected by the Adviser to match generally the performance of the Index as a whole. In addition, from time to time stocks are added to or removed from the Index. The Fund may sell stocks that are represented in the Index, or purchase stocks that are not yet represented in the Index, in anticipation of their removal from or addition to the Index. In no event will the Fund invest less than 80% of its total assets in stocks in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

In addition, the Fund may at times purchase or sell futures contracts on the Index, or options on those futures, in lieu of investment directly in the stocks making up the Index. The Fund might do so, for example, in order to increase its investment exposure pending investment of cash in the stocks comprising the Index. Alternatively, the Fund might use futures or options on futures to reduce its investment exposure in situations where it intends to sell a portion of the stocks in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Stock values could decline generally or could under-perform other investments.

- Because the S&P 400 Index includes stocks of mainly mid-capitalization ("mid-cap") companies, the Fund's investments consist mainly of stocks of mid-cap companies. Returns on investments in mid-cap stocks could be more volatile than, or trail the returns on, investments in larger or smaller capitalization ("large-cap" and "small-cap," respectively) U.S. stocks.

2

- Mid-cap companies may be more likely than large-cap companies to have relatively limited product lines, markets or financial resources, or depend on a few key employees.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to replicate the performance of the Index may not correlate precisely with the return on the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

PERFORMANCE INFORMATION.

Performance information for the Fund has been omitted because the Fund had not commenced investment operations as of the date of this Prospectus.

FEES AND EXPENSES

This table describes the estimated fees and expenses that you may pay if you buy and hold shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1)..................................  0.08%
Distribution (12b-1) Fees...........................  0.25%
Other Expenses(2)...................................  0.10%
                                                      ----
Total Annual Fund Operating Expenses................  0.43%
                                                      ====


1 This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

2 Other Expenses are based on estimated amounts for the current fiscal year.

3

Example: This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR    3 YEARS
------    -------
 $44       $138

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The S&P 400 Index. The S&P 400 Index is a well-known stock market index that includes common stocks of 400 companies from several industrial sectors representing a large cross-section of mid-cap stocks publicly traded in the United States, most of which are listed on the New York Stock Exchange, Inc. (the "NYSE"). Unlike the S&P 500 Index, which is designed to represent the performance of the large-cap sector of the U.S. securities market, the S&P 400 Index is designed to represent the performance of the mid-cap sector of the U.S. securities market. Stocks in the S&P 400 Index are weighted according to their market capitalizations (i.e., the number of shares outstanding multiplied by the stock's current price). The companies chosen for the S&P 400 Index generally have market values between $1 billion and $4 billion, depending upon current equity market valuations. (Stocks in the S&P 400 Index will not simultaneously be listed in the S&P 500 Index.) The composition of the S&P 400 Index is determined by Standard & Poor's and is based on such factors as the market capitalization and trading activity of each stock and its adequacy as a representation of stocks in a particular industry group, and may be changed from time to time. "Standard & Poor's(R)," "S&P," "S&P 400," "Standard & Poor's 400" and "400" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by the Fund. The Fund is not sponsored, endorsed, sold or promoted by S&P, and S&P makes no representation regarding the advisability of investing in the Fund.

Index Futures Contracts and Related Options. The Fund may buy and sell futures contracts on the Index and options on those futures contracts. An "index futures" contract is a contract to buy or sell units of an index at an agreed price on a specified future date. Depending on the change in value of the Index between the time when the Fund enters into and terminates an

4

index future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts on the Index will not correlate precisely with changes in the value of the Index. In those cases, use of futures contracts and related options might decrease the correlation between the return of the Fund and the return of the Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Index Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security. Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

5

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.08% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund will be available in the Fund's annual report or semi-annual report, as applicable, after the Fund commences operations.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team

6

work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

7

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity who applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

8

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.25%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

9

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax advisor for more information on your own tax situation, including possible foreign, state and local taxes.

10

For more information about STATE STREET EQUITY 400 INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments will be available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports will be available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-942-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET EQUITY 2000 INDEX FUND


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Equity 2000 Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Russell 2000(R) Index (the "Russell 2000 Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the Russell 2000 Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of the State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund uses a management strategy designed to track the performance of the Russell 2000 Index. The Russell 2000 Index is one of the most widely accepted benchmarks of U.S. small capitalization stock market total return. It includes the smallest 2,000 securities in the Russell 3000(R) Index. (For a discussion of how the securities in the Russell 2000 Index are selected, see "Other Investment Considerations and Risks -- The Russell 2000 Index" below).

The Fund, using an "indexing" investment approach, attempts to match, before expenses, the performance of the Russell 2000 Index. The Adviser

1

seeks a correlation of 0.95 or better between the Fund's performance and the performance of the Index (1.00 would represent perfect correlation).

The Fund may invest (either on its own or as part of a master-feeder structure) in all of the stocks comprising the Index in proportion to their weightings in the Index. However, under various circumstances, it may not be possible or practicable to purchase all of those stocks in those weightings. In those circumstances, the Fund may purchase a sample of the stocks in the Index in proportions expected by the Adviser to match generally the performance of the Index as a whole. In addition, from time to time stocks are added to or removed from the Index. The Fund may sell stocks that are represented in the Index, or purchase stocks that are not yet represented in the Index, in anticipation of their removal from or addition to the Index. In no event will the Fund invest less than 80% of its total assets in stocks in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

In addition, the Fund may at times purchase or sell futures contracts on the Index, or on U.S. securities, or options on those futures, in lieu of investment directly in the stocks making up the Index. The Fund might do so, for example, in order to increase its investment exposure pending investment in the stocks comprising the Index. Alternatively, the Fund might use futures or options on futures to reduce its investment exposure in situations where it intends to sell a portion of the stocks in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Stock values could decline generally or could under-perform other investments.

- Because the Russell 2000 Index includes primarily stocks of small- capitalization ("small-cap") companies, the Equity 2000 Index Fund's investments consist mainly of stocks of small-cap companies. Returns on investments in stocks of small U.S. companies could be more volatile than, or trail the returns on, investments in stocks of larger or medium capitalization ("large-cap" and "mid-cap," respectively) companies. Small companies may be more likely than mid-cap and large-

2

cap companies to have relatively limited product lines, markets or financial resources, or depend on a few key employees.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to match the performance of the Index may not correlate precisely with the return on the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

PERFORMANCE INFORMATION.

Performance information for the Fund has been omitted because the Fund had not commenced investment operations as of the date of this Prospectus.

FEES AND EXPENSES

This table describes the estimated fees and expenses that you may pay if you buy and hold shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1).................................   0.10%
Distribution (12b-1) Fees..........................   0.25%
Other Expenses(2)..................................   0.10%
                                                      ----
Total Annual Fund Operating Expenses...............   0.45%
                                                      ====


1 This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

2 Other Expenses are based on estimated amounts for the current fiscal year.

3

Example: This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR     3 YEARS
-------    -------
  $46       $144

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The Russell 2000 Index. The Russell 2000 Index is composed of 2000 common stocks, which are selected by Frank Russell Company ("Russell"), based upon market capitalization. Each year on May 31st, Russell ranks the 3,000 largest U.S. stocks by market capitalization in order to create the Russell 3000 Index, which represents approximately 98% of the total U.S. equity market. After the initial list of 3,000 eligible stocks is determined, the shares outstanding for each company are adjusted for corporate cross-ownership and large private holdings. The Russell 2000 Index is a subset of the Russell 3000 Index, representing the smallest 2000 stocks of the Russell 3000 Index. The purpose of the Russell 2000 Index is to provide a comprehensive representation of the investable U.S. small-cap equity market. The inclusion of a stock in the Russell 2000 Index in no way implies that Russell believes the stock to be an attractive investment, nor is Russell a sponsor or in any way affiliated with the Fund. The securities in the Russell 2000 Index, most of which trade on the New York Stock Exchange (the "NYSE") and Nasdaq, represent approximately 8% of the market value of all U.S. common stocks. The Index only includes common stocks domiciled in the United States and its territories.

Index Futures Contracts and Related Options. The Fund may buy and sell futures contracts on the Index and options on those futures contracts. An "index futures" contract is a contract to buy or sell units of an index at an agreed price on a specified future date. Depending on the change in value of the Index between the time when the Fund enters into and terminates an index future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts on the Index will not correlate precisely with changes in the value of the Index. In those cases, use of

4

futures contracts and related options might decrease the correlation between the return of the Fund and the return of the Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Index Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

REITs. The Fund may invest in real estate investment trusts, known as "REITs". REITs involve certain special risks in addition to those risks associated with investing in the real estate industry in general (such as possible declines in the value of real estate, lack of availability of mortgage funds or extended vacancies of property). Equity REITs may be affected by changes in the value of the underlying property owned by the REITs, while mortgage REITs may be affected by the quality of any credit extended. REITs are dependent upon management skills, are subject to heavy cash flow dependency, risks of default by borrowers, and self-liquidation. REITs are also subject to the possibilities of failing to qualify for tax-free pass-through of income under the Internal Revenue Code, and failing to maintain their exemptions from registration under the 1940 Act. Investing in REITs involves risks similar to those associated with investing in small cap companies. REITs may have limited financial resources, may trade less frequently and in limited volume and may be subject to more volatility than other investments.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security.

5

Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser, pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.10% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets

6

in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund will be available in the Fund's annual report or semi-annual report, as applicable, after the Fund commences operations.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not

7

readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity who applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult

8

your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

9

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.25%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

10

For more information about STATE STREET EQUITY 2000 INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments will be available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports will be available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-942-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET AGGREGATE
BOND INDEX FUND


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.


INTRODUCTION

The State Street Aggregate Bond Index Fund (the "Fund") is a mutual fund that seeks to provide an investment return matching, as closely as possible before expenses, the performance of the Lehman Brothers Aggregate Bond Index (the "LBAB Index" or the "Index"). The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and to the portfolio in which it invests.

RISK/RETURN SUMMARY

INVESTMENT OBJECTIVE.

The Fund's investment objective is to match as closely as possible, before expenses, the performance of the LBAB Index. The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in a corresponding portfolio (the "Portfolio") of the State Street Master Funds that has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and policies of the Fund below, you should assume that the investment objective and policies of the Portfolio are the same in all material respects as those of the Fund (and that, at times when the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio). There is no assurance that the Fund will achieve its investment objective.

PRINCIPAL INVESTMENT STRATEGIES.

The Fund uses a management strategy designed to track the performance of the LBAB Index. The LBAB Index is a well-known fixed-income securities index, which emphasizes U.S. government securities, mortgage-backed securities and corporate investment-grade debt securities.

The Adviser seeks to track the performance of the LBAB Index by investing in debt securities and other investments that are representative of the LBAB Index as a whole. Due to the large number of securities in the LBAB Index and the fact that certain Index securities are unavailable for purchase, complete replication is not possible. Rather, the Fund intends to

1

select securities that the Adviser believes will track the LBAB Index in terms of industry weightings, market capitalization and other characteristics. In no event will the Fund invest less than 80% of its total assets in securities in the Index under normal market conditions. Shareholders will receive 60 days' notice prior to changing the 80% investment policy.

The Fund may make direct investments in U.S. government securities; corporate debt securities; mortgage-backed and other asset-backed securities; commercial paper, notes, and bonds issued by domestic and foreign corporations; instruments of U.S. and foreign banks, including certificates of deposit, time deposits, letters of credit, and bankers' acceptances; and swap agreements. Securities in which the Fund invests may be fixed-income securities, zero-coupon securities, or variable rate securities.

In addition, the Aggregate Bond Index Fund may at times purchase or sell futures contracts on fixed-income securities, or options on those futures, in lieu of investment directly in fixed-income securities themselves. The Fund may also purchase or sell futures contracts and options on the LBAB Index (or other fixed-income securities indices), if and when they become available. The Fund might do so, for example, in order to adjust the interest-rate sensitivity of the Fund to bring it more closely in line with that of the Index. It might also do so to increase its investment exposure pending investment of cash in the bonds comprising the Index or to reduce its investment exposure in situations where it intends to sell a portion of the securities in its portfolio but the sale has not yet been completed. The Fund may also, to the extent permitted by applicable law, invest in shares of other mutual funds whose investment objectives and policies are similar to those of the Fund. The Fund may also enter into other derivatives transactions, including the purchase or sale of options or enter into swap transactions, to assist in matching the performance of the Index.

PRINCIPAL RISKS.

- Values of fixed-income securities could decline generally in response to changes in interest rates or other factors. In general, the price of a fixed-income security may fall when interest rates rise and may rise when interest rates fall. Securities with longer maturities may be more sensitive to interest rate changes than securities with shorter maturities are.

- Returns on investments in fixed-income securities could trail the returns on other investment options, including investments in equity securities.

2

- Issuers of the Fund's investments may not make timely payments of interest and principal or may fail to make such payments at all.

- The Fund's return may not match the return of the Index for a number of reasons. For example, the return on the securities and other investments selected by the Adviser may not correlate precisely with the return on the Index. The Fund incurs a number of operating expenses not applicable to the Index, and incurs costs in buying and selling securities. The Fund may not be fully invested at times, either as a result of cash flows into the Fund or reserves of cash held by the Fund to meet redemptions. The return on the sample of stocks purchased by the Adviser, or futures or other derivative positions taken by the Adviser, to replicate the performance of the Index may not correlate precisely with the return of the Index.

THE FUND'S SHARES WILL CHANGE IN VALUE, AND YOU COULD LOSE MONEY BY INVESTING IN THE FUND. THE FUND MAY NOT ACHIEVE ITS INVESTMENT OBJECTIVE. AN INVESTMENT IN THE FUND IS NOT A DEPOSIT WITH A BANK AND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

PERFORMANCE INFORMATION.

Performance information for the Fund has been omitted because the Fund had not commenced investment operations as of the date of this Prospectus.

FEES AND EXPENSES

The following table describes the estimated fees and expenses that you may pay if you buy and hold shares of the Fund. As a shareholder in a Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1).................................   0.10%
Distribution (12b-1) Fees..........................   0.25%
Other Expenses(2)..................................   0.10%
                                                      ----
Total Annual Fund Operating Expenses...............   0.45%
                                                      ====


1 This fee represents the total expenses of the corresponding Portfolio of the State Street Master Funds.

2 Other Expenses are based on estimated amounts for the current fiscal year.

3

Example: This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR    3 YEARS
------    -------
 $46       $144

OTHER INVESTMENT CONSIDERATIONS AND RISKS

The LBAB Index. The LBAB Index is a well-known bond market index that covers the U.S. investment-grade fixed-income bond market, including government, corporate, mortgage-backed and asset-backed bonds, all with maturities of over one year. Bonds in the LBAB Index are weighted according to their market capitalizations. The composition of the Index is determined by Lehman Brothers Holdings, Inc. ("Lehman Brothers") and is based on such factors as the market capitalization of each bond, its remaining time to maturity and quality rating as determined by Moody's Investor Securities, Inc., an outside rating agency, and may be changed from time to time. The Fund is not sponsored, endorsed, sold, or promoted by Lehman Brothers, and Lehman Brothers makes no representation regarding the advisability of investing in the Fund.

Debt Securities. The values of debt securities generally rise and fall inversely with changes in interest rates. Interest rate risk is usually greater for debt securities with longer maturities. The Fund's investments will normally include debt securities with longer maturities, although the Adviser will seek to ensure that the maturity characteristics of the Fund as a whole will generally be similar to those of the LBAB Index. Mortgage-backed and asset-backed securities are also subject to increased interest rate risk, because prepayment rates on such securities typically increase as interest rates decline and decrease as interest rates rise. Changes in prepayment rates on mortgage-backed and asset-backed securities effectively increase and decrease the Fund's average maturity when that is least desirable. The Fund will also be subject to credit risk (the risk that the issuer of a security will fail to make timely payments of interest and principal).

Futures Contracts and Related Options. The Fund may buy and sell futures contracts on securities contained in the LBAB Index and options on

4

those futures contracts. A "futures contract" on debt securities (such as U.S. Treasury securities) is a contract to buy or sell the securities at an agreed price on a specified future date. Depending on the change in value of the futures contract between the time when the Fund enters into and terminates a future or option transaction, the Fund realizes a gain or loss. Options and futures transactions involve risks. For example, it is possible that changes in the prices of futures contracts will not correlate precisely with changes in the value of the underlying security. In those cases, use of futures contracts and related options might decrease the correlation between the return of the Fund and the return of the LBAB Index. In addition, the Fund incurs transaction costs in entering into, and closing out, positions in futures contracts and related options. These costs typically have the effect of reducing the correlation between the return of the Fund and the return of the LBAB Index.

Other Derivative Transactions. The Fund may enter into derivatives transactions involving options and swaps. These transactions involve many of the same risks as those described above under "Futures Contracts and Related Options." In addition, since many of such transactions are conducted directly with counterparties, and not on an exchange or board of trade, the Fund's ability to realize any investment return on such transactions may be dependent on the counterparty's ability or willingness to meet its obligations.

Repurchase Agreements and Securities Loans. The Fund may enter into repurchase agreements and securities loans. Under a repurchase agreement, the Fund purchases a debt instrument for a relatively short period (usually not more than one week), which the seller agrees to repurchase at a fixed time and price, representing the Fund's cost plus interest. Under a securities loan, the Fund lends portfolio securities. The Fund will enter into repurchase agreements and securities loans only with commercial banks and with registered broker-dealers who are members of a national securities exchange or market makers in government securities, and in the case of repurchase agreements, only if the debt instrument is a U.S. government security. Although the Adviser will monitor these transactions to ensure that they will be fully collateralized at all times, the Fund bears a risk of loss if the other party defaults on its obligation and the Fund is delayed or prevented from exercising its rights to dispose of the collateral. If the other party should become involved in bankruptcy or insolvency proceedings, it is possible that the Fund may be treated as an unsecured creditor and be required to return the underlying collateral to the other party's estate.

5

Changes in Policies. The Trust's Board of Trustees may change the Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board of Trustees will not materially change the Fund's investment objective without shareholder approval.

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser for the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser, pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.10% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund will be available in the Fund's

6

annual report or semi-annual report, as applicable, after the Fund commences operations.

The Adviser manages the Portfolio using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities including investment strategy and analysis while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within the firm. Each portfolio management team is overseen by the SSgA Investment Committee.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund's net asset value ("NAV") is calculated on each day the New York Stock Exchange (the "NYSE") is open as of the close of regular trading on the NYSE. The NAV is based on the market value of the securities held in the Fund. The NAV per share is calculated by dividing the value of the NAV of the Fund by the number of shares outstanding. The Fund values each security pursuant to guidelines adopted by the Board of Trustees. Securities may be valued at fair value, as determined in good faith and pursuant to procedures approved by the Portfolio's Board of Trustees, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities held by the Fund occurs after the close of a related exchange but before the determination of the Fund's NAV. Attempts to determine the fair value of securities introduce an element of subjectivity to the pricing of securities. As a result, the price of a security determined through fair valuation techniques may differ from the price

7

quoted or published by other sources and may not accurately reflect the market value the Fund would have received had it sold the investment.

Purchasing Shares. Investors pay no sales load to invest in this Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity who applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason, including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions.) The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Acto of 1940, as amended, if an emergency exists.

8

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, dilution in the value of Fund shares held by long-term shareholders, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Fund is intended as a long-term investment. Therefore, the Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

9

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.25%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

Income dividends and capital gains distributions of the Fund will be declared and paid at least annually.

For federal income tax purposes, distributions of investment income are generally taxable as ordinary income. Taxes on distributions of capital gains are determined by how long the Fund owned the investments that generated them, rather than how long you have owned your shares. Distributions are taxable to you even if they are paid from income or gains earned by the Fund before your investment (and thus were included in the price you paid). Distributions of gains from investments that the Fund owned for more than one year that are properly designated by the Fund as capital gains dividends will be taxable as long-term capital gains. Distributions of gains from investments that the Fund owned for one year or less will be taxable as ordinary income. Certain distributions designated as "qualified dividends" are generally taxable to an individual shareholder at his or her maximum long-term capital-gains rate. Distributions may also be subject to state and local taxes and are taxable whether you received them in cash or reinvested them in additional shares. Distributions are generally taxable to shareholders in the calendar year in which the distributions are declared, rather than the calendar year in which the distributions are received.

Any gain resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

10

For more information about STATE STREET AGGREGATE BOND INDEX FUND:

The Fund's statement of additional information (SAI) includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments will be available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports will be available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-942-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST
P.O. BOX 5049
BOSTON, MASSACHUSETTS 02206


STATE STREET U.S. GOVERNMENT
MONEY MARKET FUND


PROSPECTUS DATED APRIL 28, 2006


THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED THESE SECURITIES OR PASSED UPON THE ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

AN INVESTMENT IN THE STATE STREET U.S. GOVERNMENT MONEY MARKET FUND IS NOT INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY OTHER GOVERNMENT AGENCY.

The State Street U.S. Government Money Market Fund's investment objective is to maximize current income, to the extent consistent with the preservation of capital and liquidity and the maintenance of a stable $1.00 per share net asset value, by investing in obligations of the U.S. government or its instrumentalities with remaining maturities of one year or less.


INTRODUCTION

The State Street U.S. Government Money Market Fund's (the "Fund") investment objective is to maximize current income, to the extent consistent with the preservation of capital and liquidity and the maintenance of a stable $1.00 per share net asset value ("NAV"), by investing in obligations of the U.S. government or its instrumentalities with remaining maturities of one year or less. The Fund is a series of the State Street Institutional Investment Trust (the "Trust"), an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts. SSgA Funds Management, Inc. (the "Adviser"), a subsidiary of State Street Corporation, is the investment adviser to the Fund and the Portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing substantially all of its investable assets in the State Street U.S. Government Money Market Portfolio (the "Portfolio") of State Street Master Funds, which has the same investment objective as, and investment policies that are substantially similar to those of, the Fund. In reviewing the investment objective and strategies of the Fund below, you should assume that the investment objective and strategies of the Portfolio are the same in all material respects as those of the Fund and that, so long as the Fund has invested its assets in the Portfolio, the descriptions below of the Fund's investment strategies and risks should be read as also applicable to the Portfolio.

The Fund attempts to meet its investment objective by investing under normal circumstances substantially all of its assets (either on its own or as part of a master-feeder structure) in obligations issued or guaranteed as to principal or interest by the U.S. government or its agencies or instrumentalities ("U.S. government securities") or in repurchase agreements with respect to U.S. government securities, but in no event will it invest less than 80% of its total assets in U.S. government securities under normal market conditions. Shareholders will receive 60 days notice prior to changing the 80% investment policy. The Adviser bases its investment decisions on the relative attractiveness of different money market investments which can vary depending on the general level of interest rates as well as supply/demand imbalances in the market. There are risks associated with these instruments, which are summarized below.

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A money market fund must limit its investments to securities with remaining maturities determined in accordance with applicable SEC regulations and must maintain a dollar-weighted average maturity of 90 days or less. The Fund will normally hold portfolio instruments to maturity, but may dispose of them prior to maturity if the Adviser finds it advantageous or necessary. Investing in short-term money market instruments will result in high portfolio turnover. Since the cost of these transactions is small, high turnover is not expected to adversely affect the Fund's price or yield.

PRINCIPAL RISKS OF INVESTING IN THE FUND

Money Market Risk. The Fund may not be able to maintain a NAV per share of $1.00 at all times. Although the Fund seeks to maintain a constant NAV of $1.00 per share, the Fund may not be able to do so at all times, and it is possible for you to lose money by investing in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Interest Rate Risk. During periods of rising interest rates, the Fund's yield may tend to be lower than prevailing market rates; in periods of falling interest rates, the Fund's yield may be higher than prevailing market rates.

U.S. Government Securities Risk. Although securities issued directly by the U.S. government are guaranteed by the U.S. Treasury, other securities issued by an agency or instrumentality of the U.S. government may not be. No assurance can be given that the U.S. government would provide financial support to its agencies and instrumentalities if not required to do so by law.

Management Strategy Risk. A strategy used by the Adviser may fail to produce the intended results.

Liquidity Risk. The Fund may be unable to pay redemption proceeds within the time period stated in this prospectus because of unusual market conditions, an unusually high volume of redemption requests, or other reasons.

Fixed-Income Securities Risk. The risks of fixed-income securities include, but are not limited to, interest rate risk, credit risk and call/extension risk. Credit risk involves the risk that the issuer could default on its obligations, and the Fund will not recover its investment. Call risk and

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extension risk are normally present in adjustable rate mortgage loans, mortgage-backed securities and asset-backed securities.

PERFORMANCE INFORMATION

Performance information for the Fund has been omitted because the Fund has not commenced operations as of the date of this Prospectus.

FEES AND EXPENSES

The following table describes the estimated fees and expenses that you may pay if you buy and hold shares of the Fund. As a shareholder in the Portfolio, the Fund bears its ratable share of the Portfolio's expenses, including advisory and administrative fees, and at the same time continues to pay its own fees and expenses. The table and the Example reflect the expenses of both the Fund and the Portfolio.

Annual Fund Operating Expenses (expenses that are deducted from Fund assets)

Management Fees(1)................................    0.15%
Distribution (12b-1) Fees.........................    0.05%
Other Expenses(2).................................    0.08%
                                                     -----
Total Annual Fund Operating Expenses..............    0.28%
                                                     =====


1 This fee represents the total estimated expenses of the corresponding Portfolio of the State Street Master Funds.

2 Other Expenses are based on estimated amounts for the current fiscal year.

Example: This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 YEAR     3 YEARS
-------    -------
  $29        $90

MANAGEMENT AND ORGANIZATION

The Fund and the Portfolio. The Trust is an open-end management investment company and was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000. The Fund is a separate diversified series of the Trust. The Portfolio in which the Fund

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invests is managed under the general oversight of the Board of Trustees of State Street Master Funds. SSgA Funds Management, Inc., a subsidiary of State Street Corporation, serves as the investment adviser the Portfolio.

The Trust's Board of Trustees is responsible for generally overseeing the investment of the Fund's assets. If the Adviser were to invest the Fund's assets directly, it would, subject to such policies as the Board of Trustees may determine, furnish a continuing investment program for the Fund and make investment decisions on its behalf.

The Adviser. State Street Global Advisors ("SSgA") is the investment management group of State Street Corporation and includes the Adviser. SSgA is one of the world's largest institutional money managers, and uses quantitative and traditional techniques to manage approximately $1.4 trillion as of December 31, 2005 in investment programs and portfolios for institutional and individual investors. The Adviser is registered with the Securities and Exchange Commission
("SEC") under the Investment Advisers Act of 1940, as amended ("Advisers Act")
and is a wholly-owned subsidiary of State Street Corporation, a publicly held bank holding company. It had over $96 billion in assets under management at December 31, 2005. The Fund has entered into an investment advisory agreement with the Adviser pursuant to which the Adviser would manage the Fund's assets directly, at an annual rate of 0.10% of the Fund's average daily net assets, in the event that the Fund were to cease investing substantially all of its assets in the Portfolio. The Adviser does not receive any fees from the Fund under that agreement so long as the Fund continues to invest substantially all of its assets in the Portfolio or in another investment company. The Adviser places all orders for purchases and sales of the underlying Portfolio's investments.

A discussion regarding the basis for the Board of Trustees' approval of the investment advisory agreement for the Fund will be available in the Fund's annual report or semi-annual report, as applicable, after the Fund commences operations.

The Adviser's principal address is State Street Financial Center, One Lincoln Street, Boston, Massachusetts 02111.

The Administrator, Custodian, Transfer and Dividend Disbursing Agent. State Street Bank and Trust Company ("State Street"), a subsidiary of State Street Corporation, is the administrator, custodian and transfer agent for the Fund.

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ADDITIONAL INFORMATION ABOUT THE FUND'S OBJECTIVES, INVESTMENT STRATEGIES AND RISKS

The investment objective of the Fund as stated above may be changed without shareholder approval. The investment policies described below reflect the Fund's current practices. In addition to the principal risks explained above, other risks are explained in some of the descriptions of the investment policies below:

U.S. Government Securities. U.S. government securities include U.S. Treasury bills, notes, bonds and other obligations issued or guaranteed as to interest or principal by the U.S. government, its agencies or instrumentalities. U.S. government securities may include securities that are supported by the full faith and credit of the United States Treasury, and securities that are supported only by the right of the issuer to borrow from the United States Treasury, by the discretionary authority of a U.S. government agency or instrumentality, or solely by the creditworthiness of the issuer.

Variable and Floating Rate Securities. The Fund may purchase variable and floating rate securities which are instruments issued or guaranteed by entities such as the: (1) U.S. government, or an agency or instrumentality thereof, (2) corporations, (3) financial institutions or (4) insurance companies. The interest rate on a variable rate security typically adjusts automatically on fixed dates or after specified periods of time. The interest rate on a floating rate security typically adjusts automatically in response to specified interest rate changes. Interest rates on these securities are ordinarily tied to, and are a percentage of, a widely recognized interest rate, such as the yield on 90-day U.S. Treasury bills or the prime rate of a specified bank.

SHAREHOLDER INFORMATION

Determination of Net Asset Value. The Fund determines the price (or NAV) per share once each business day at 4:00 p.m. Eastern time, or the close of the New York Stock Exchange (the "NYSE"), if earlier. Pricing does not occur on NYSE holidays. A business day is one on which the NYSE is open for regular trading. The Federal Reserve is closed on certain holidays on which the NYSE is open. These holidays are Columbus Day and Veteran's Day. On these holidays, you will not be able to purchase shares by wiring Federal Funds because the Federal Funds wiring does not occur on these holidays. Payment for Fund shares must be in Federal Funds (or

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converted to Federal Funds by the Transfer Agent) by 4 p.m. ET before a purchase order can be accepted.

The price per share for the Fund is computed by adding the value of all securities and other assets of the Fund, deducting accrued liabilities, dividing by the number of shares outstanding and rounding to the nearest cent.

The Fund seeks to maintain a $1.00 per share NAV and, accordingly, uses the amortized cost valuation method to value its portfolio instruments. The amortized cost valuation method initially prices an instrument at its cost and thereafter assumes a constant amortization to maturity of any discount or premium, regardless of the impact of fluctuating interest rates on the market value of the instrument.

Purchasing Shares. Investors pay no sales load to invest in the Fund. The price for Fund shares is the NAV per share. Orders will be priced at the NAV next calculated after the order is accepted by the Fund.

The minimum initial investment in the Fund is $25 million, although the Adviser may waive the minimum in its discretion. There is no minimum subsequent investment. The Fund intends to be as fully invested as is practicable; therefore, investments must be made either in Federal Funds (i.e., monies credited to the account of the Fund's custodian bank by a Federal Reserve Bank) or securities ("in-kind") acceptable to the Adviser. (Please consult your tax adviser regarding in-kind transactions.) On Columbus Day and Veteran's Day, you will not be able to purchase shares by wiring Federal Funds because the Federal Funds wiring does not occur on those days. Payment for Fund shares must be in Federal Funds (or converted to Federal Funds by the Transfer Agent) by 4 p.m. ET before a purchase order can be accepted. The Fund reserves the right to cease accepting investments at any time or to reject any investment order.

In accordance with certain federal regulations, the Trust is required to obtain, verify and record information that identifies each entity who applies to open an account. For this reason, when you open (or change ownership of) an account, the Trust will request certain information, including your name, address and taxpayer identification number which will be used to verify your identity. If you are unable to provide sufficient information to verify your identity, the Trust will not open an account for you. As required by law, the Trust may employ various procedures, such as comparing your information to fraud databases or requesting additional information and documentation from you, to ensure that the information supplied by you is correct. The Trust reserves the right to reject any purchase for any reason,

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including failure to provide the Trust with information necessary to confirm your identity as required by law.

Redeeming Shares. An investor may withdraw all or any portion of its investment at the NAV next determined after it submits a withdrawal request, in proper form, to the Fund. The Fund will pay the proceeds of the withdrawal either in Federal Funds or in securities at the discretion of the Adviser, normally on the next Fund business day after the withdrawal, but in any event no more than seven days after the withdrawal. (Please consult your tax adviser regarding in-kind transactions). The right of any investor to receive payment with respect to any withdrawal may be suspended or the payment of the withdrawal proceeds postponed during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or, to the extent otherwise permitted by the Investment Company Act of 1940, as amended, if an emergency exists.

Policies to Prevent Market Timing. Frequent purchases and redemptions of Fund shares may present risks for other shareholders of the Fund, which may include, among other things, interference in the efficient management of the Fund's portfolio, increased brokerage and administrative costs and forcing the Fund to hold excess levels of cash.

The Trust's Board of Trustees has adopted policies and procedures designed to detect and prevent inappropriate short-term trading activity that is harmful to the Fund. Because most of the interests in the Fund are held by investors indirectly through one or more financial intermediaries, the Fund does not generally have information about the identity of those investors or about transactions effected by those investors. Rather, the Fund and its service providers periodically review cash inflows and outflows from and to those intermediaries in an attempt to detect inappropriate trading activity by investors holding shares through those intermediaries. The Fund may not be able to determine whether trading by an investor holding shares through a financial intermediary is engaged in trading activity in the Fund's shares that may be harmful to the Fund or its shareholders.

The Fund reserves the right in its discretion to reject any purchase, in whole or in part including, without limitation, by a person whose trading activity in Fund shares the Adviser believes could be harmful to the Fund. The Fund may decide to restrict purchase and sale activity in its shares based on various factors, including, without limitation, whether frequent purchase and sale activity will disrupt portfolio management strategies and adversely affect performance. There can be no assurance that the Fund, the Adviser or State Street will identify all frequent purchase and sale activity affecting the Fund.

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PORTFOLIO HOLDINGS DISCLOSURE

The Fund's portfolio holdings disclosure policy is described in the Statement of Additional Information.

DISTRIBUTION/SERVICING (RULE 12b-1) PLAN

The Fund has adopted a distribution plan under which the Fund may compensate its distributor (or others) for services in connection with the distribution of the Fund's shares and for services provided to Fund shareholders. The plan calls for payments at an annual rate (based on average daily net assets) of 0.05%. Because these fees are paid out of the Fund's assets on an ongoing basis, they will increase the cost of your investment and may cost you more over time than paying other types of sales charges.

DIVIDENDS, DISTRIBUTIONS AND TAX CONSIDERATIONS

The Fund intends to declare dividends on shares from net investment income daily and pay them as of the last business day of each month. Distributions from capital gains, if any, will be made annually in December.

Dividends from net investment income and distributions of net short-term capital gains are taxable to you as ordinary income under federal income tax laws whether paid in cash or in additional shares.

Any gains resulting from the sale or exchange of your shares will generally also be subject to tax. You should consult your tax adviser for more information on your own tax situation, including possible foreign, state and local taxes.

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For more information about STATE STREET U.S. GOVERNMENT MONEY MARKET FUND:

The Fund's SAI includes additional information about the Fund and is incorporated by reference into this document. Additional information about the Fund's investments will be available in the Fund's annual and semi-annual reports to shareholders. In the Fund's annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund's performance during its last fiscal year.

The SAI and the Fund's annual and semi-annual reports will be available, without charge, upon request. Shareholders in the Fund may make inquiries to the Fund to receive such information by calling (877) 521-4083. The Fund does not have an Internet website.

Information about the Fund (including the SAI) can be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-202-942-8090. Reports and other information about the Fund are available free of charge on the EDGAR Database on the Commission's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address:
publicinfo@sec.gov, or by writing the Commission's Public Reference Section, Washington, D.C. 20549-0102.

SSGA FUNDS MANAGEMENT, INC.
State Street Financial Center
One Lincoln Street
Boston, Massachusetts 02111

The State Street Institutional Investment Trust's Investment Company Act File Number is 811-9819.


STATE STREET INSTITUTIONAL INVESTMENT TRUST

STATE STREET EQUITY 500 INDEX FUND

STATE STREET EQUITY 400 INDEX FUND

STATE STREET EQUITY 2000 INDEX FUND

STATE STREET AGGREGATE BOND INDEX FUND

STATE STREET INSTITUTIONAL LIQUID RESERVES FUND

STATE STREET U.S. GOVERNMENT MONEY MARKET FUND

State Street Institutional Investment Trust P.O. Box 5049 Boston, Massachusetts 02206

APRIL 28, 2006

This Statement of Additional Information ("SAI") dated April 28, 2006 relates to the prospectuses dated April 28, 2006 (the "Prospectuses") for the State Street Equity 500 Index Fund, State Street Equity 400 Index Fund, State Street Equity 2000 Index Fund, State Street Aggregate Bond Index Fund, State Street Institutional Liquid Reserves Fund and State Street U.S. Government Money Market Fund.

The SAI is not a prospectus and should be read in conjunction with the Prospectuses. To obtain a copy of a Prospectus, please call the customer service center at the telephone number shown in the accompanying Contract prospectus, if applicable, or write the Trust at the address listed above.

The State Street Institutional Investment Trust's (the Trust") financial statements for the fiscal year ended December 31, 2005, including the independent registered public accounting firm report thereon, are included in the Trust's annual report and are incorporated into this SAI by reference. A copy of the Trust's annual report is available, without charge, upon request, by calling the customer service center at the telephone number shown in the accompanying Contract prospectus, if applicable, or by writing the Trust at the address above.

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TABLE OF CONTENTS

Trust History ............................................................     3
Description of the Funds and Their Investments and Risks .................     3
Additional Investments and Risks .........................................     5
Management of the Trust ..................................................    16
Control Persons and Principal Holders of Securities ......................    19
Investment Advisory and Other Services ...................................    20
Brokerage Allocation and Other Practices .................................    24
Capital Stock and Other Securities .......................................    25
Purchase, Redemption and Pricing of Shares ...............................    25
Taxation of the Funds ....................................................    26
Underwriters .............................................................    28
Calculation of Performance Data ..........................................    28
Financial Statements .....................................................    30
Appendix A - Ratings of Debt Instruments .................................   A-1
Appendix B - Trust's Proxy Voting Procedures .............................   B-1
Appendix C - Adviser's Proxy Voting Procedures ...........................   C-1

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TRUST HISTORY

The Trust was organized as a business trust under the laws of the Commonwealth of Massachusetts on February 16, 2000.

The Trust is an open-end management investment company. The Trust contains the following diversified series:

- State Street Equity 500 Index Fund (the "Equity 500 Index Fund");

- State Street Equity 400 Index Fund (the "Equity 400 Index Fund");

- State Street Equity 2000 Index Fund (the "Equity 2000 Index Fund");

- State Street Aggregate Bond Index Fund (the "Aggregate Bond Index Fund");

- State Street Institutional Liquid Reserves Fund (the "Liquid Reserves Fund"); and

- State Street U.S. Government Money Market Fund (the "U.S.


Government Money Market Fund").

The Equity 500 Index Fund, the Equity 400 Index Fund, the Equity 2000 Index Fund and the Aggregate Bond Index Fund are referred to in this SAI as the "Index Funds." The Liquid Reserves Fund and the U.S. Government Money Market Fund are referred to in this SAI as the "Money Funds" or "Money Market Funds." The Index Funds together with the Money Funds are referred to in this SAI as the "Funds."

DESCRIPTION OF THE FUNDS AND THEIR INVESTMENTS AND RISKS

Each Fund's Prospectus contains information about the investment objective and policies of that Fund. This SAI should only be read in conjunction with the Prospectus of the Fund or Funds in which you intend to invest. In addition to the principal investment strategies and the principal risks of the Fund described in the Fund's Prospectus, a Fund may employ other investment practices and may be subject to additional risks, which are described below.

Additional Information Concerning the S&P 500 Index

The Equity 500 Index Fund is not sponsored, endorsed, sold or promoted by Standard & Poor's, a division of The McGraw-Hill Companies, Inc. ("S&P"). S&P makes no representation or warranty, express or implied, to the owners of shares of the Equity 500 Index Fund or any member of the public regarding the advisability of investing in securities generally or in the Fund particularly or the ability of the S&P 500 Index to track general stock market performance. S&P's only relationship to the Equity 500 Index Fund is the licensing of certain trademarks and trade names of S&P and of the S&P 500 Index, which is determined, composed and calculated by S&P without regard to the Fund. S&P has no obligation to take the needs of the Equity 500 Index Fund or the owners of shares of the Fund into consideration in determining, composing or calculating the S&P 500 Index. S&P is not responsible for and has not participated in the determination of the price and number of shares of the Equity 500 Index Fund or the timing of the issuance or sale of shares of the Fund, or calculation of the equation by which shares of the Fund are redeemable for cash.

S&P has no obligation or liability in connection with the administration, marketing or trading of shares of the Equity 500 Index Fund. S&P does not guarantee the accuracy or the completeness of the S&P 500 Index or any data included therein and S&P shall have no liability for any errors, omissions or interruptions therein. S&P makes no warranty, express or implied, as to results to be obtained by the Equity 500 Index Fund, owners of shares of the Fund or any other person or entity from the use of the S&P 500 Index or any data included therein. S&P makes no express or implied warranties, and expressly disclaims all warranties of merchantability or fitness for a particular purpose or use with respect to the S&P 500 Index or any data included therein. Without limiting any of the foregoing, in no event shall S&P have any liability for any special, punitive, indirect or consequential damages (including lost profits), even if notified of the possibility of such damages.

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Additional Information Concerning the S&P 400 Index

The Equity 400 Index Fund is not sponsored, endorsed, sold or promoted by S&P. S&P makes no representation or warranty, express or implied, to the owners of shares of the Equity 400 Index Fund or any member of the public regarding the advisability of investing in securities generally or in the Fund particularly or the ability of the S&P 400 Index to track general stock market performance. S&P's only relationship to the Equity 400 Index Fund is the licensing of certain trademarks and trade names of S&P and of the S&P 400 Index, which is determined, composed and calculated by S&P without regard to the Equity 400 Index Fund. S&P has no obligation to take the needs of the Equity 400 Index Fund or the owners of shares of the Fund into consideration in determining, composing or calculating the S&P 400 Index. S&P is not responsible for and has not participated in the determination of the price and number of shares of the Equity 400 Index Fund or the timing of the issuance or sale of shares of the Fund, or calculation of the equation by which shares of the Fund are redeemable for cash.

S&P has no obligation or liability in connection with the administration, marketing or trading of shares of the Equity 400 Index Fund. S&P does not guarantee the accuracy or the completeness of the S&P 400 Index or any data included therein and S&P shall have no liability for any errors, omissions or interruptions therein. S&P makes no warranty, express or implied, as to results to be obtained by the Equity 400 Index Fund, owners of shares of the Fund or any other person or entity from the use of the S&P 400 Index or any data included therein. S&P makes no express or implied warranties, and expressly disclaims all warranties of merchantability or fitness for a particular purpose or use with respect to the S&P 400 Index or any data included therein. Without limiting any of the foregoing, in no event shall S&P have any liability for any special, punitive, indirect or consequential damages (including lost profits), even if notified of the possibility of such damages.

Additional Information Concerning the Russell 2000 Index

The Equity 2000 Index Fund is not sponsored, endorsed, promoted by, or in any way affiliated with Frank Russell Company ("Russell"). Russell is not responsible for and has not reviewed the Equity 2000 Index Fund or any associated literature or publications, and Russell makes no representation or warranty, express or implied, as to their accuracy or completeness, or otherwise. Russell reserves the right, at any time and without notice, to alter, amend, terminate or in any way change the Russell 2000 Index. Russell has no obligation to take the needs of any particular fund or its participants or any other product or person into consideration in determining, composing or calculating the Russell 2000 Index. Russell's publication of the Index in no way suggests or implies an opinion by Russell as to the attractiveness or appropriateness of investment in any or all securities upon which the Index is based. Russell makes no representation, warranty or guarantee as to the accuracy, completeness, reliability, or otherwise of the Russell 2000 Index or any data included in the Index. Russell makes no representation or warranty regarding the use, or the results of use, of the Russell 2000 Index or any data included therein, or any security (or combination thereof) comprising the Index. Russell makes no express or implied warranties, and expressly disclaims all warranties of merchantability or fitness for a particular purpose with respect to the Russell 2000 Index or any data or any security (or combination thereof) included therein.

Additional Information Concerning the Lehman Brothers Aggregate Bond Index (the "LBAB Index")

The Aggregate Bond Index Fund is not sponsored, endorsed, sold or promoted by Lehman Brothers Holdings, Inc. ("Lehman Brothers"). Lehman Brothers makes no representation or warranty, express or implied, to the owners of shares of the Aggregate Bond Index Fund or any member of the public regarding the advisability of investing in securities generally or in the Fund particularly or the ability of the LBAB Index to track general performance. Lehman Brothers' only relationship to the Aggregate Bond Index Fund is the licensing of certain trademarks and trade names of Lehman Brothers and of the LBAB Index, which is determined, composed and calculated by Lehman Brothers without regard to the Fund. Lehman Brothers has no obligation to take the needs of the Aggregate Bond Index Fund or the owners of shares of the Fund into consideration in determining, composing or calculating the LBAB Index. Lehman Brothers is not responsible for and has not participated in the determination of the price and number of shares of the Aggregate Bond Index Fund or the timing of the issuance or sale of shares of the Fund.

Lehman Brothers has no obligation or liability in connection with the administration, marketing or trading of shares of the Aggregate Bond Index Fund. Lehman Brothers does not guarantee the accuracy or the completeness

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of the LBAB Index or any data included therein and Lehman Brothers shall have no liability for any errors, omissions or interruptions therein. Lehman Brothers makes no warranty, express or implied, as to results to be obtained by the Aggregate Bond Index Fund, owners of shares of the Fund or any other person or entity from the use of the LBAB Index or any data included therein. Lehman Brothers makes no express or implied warranties, and expressly disclaims all warranties of merchantability or fitness for a particular purpose or use with respect to the LBAB Index or any data included therein. Without limiting any of the foregoing, in no event shall Lehman Brothers have any liability for any special, punitive, indirect or consequential damages (including lost profits), even if notified of the possibility of such damages.

ADDITIONAL INVESTMENTS AND RISKS

To the extent consistent with its investment objective and restrictions, each Fund may invest in the following instruments and use the following techniques.

Cash Reserves

Each Index Fund may hold portions of its assets in short-term debt instruments with remaining maturities of 397 days or less pending investment or to meet anticipated redemptions and day-to-day operating expenses. Short-term debt instruments consist of: (i) short-term obligations of the U.S. government, its agencies, instrumentalities, authorities or political subdivisions; (ii) other short-term debt securities rated at the time of purchase Aa or higher by Moody's Investors Service, Inc. ("Moody's") or AA or higher by S&P or, if unrated, of comparable quality in the opinion of SSgA Funds Management, Inc. (the "Adviser"); (iii) commercial paper; (iv) bank obligations, including negotiable certificates of deposit, time deposits and bankers' acceptances; and
(v) repurchase agreements. At the time an Index Fund invests in commercial paper, bank obligations or repurchase agreements, the issuer or the issuer's parent must have outstanding debt rated Aa or higher by Moody's or AA or higher by S&P or outstanding commercial paper or bank obligations rated Prime-1 by Moody's or A-1 by S&P; or, if no such ratings are available, the instrument must be of comparable quality in the opinion of the Adviser. To the extent that an Index Fund holds the foregoing instruments its ability to track its corresponding Index may be adversely affected. See Appendix A for more information on the ratings of debt instruments.

Futures Contracts and Options on Futures

Each Index Fund may enter into futures contracts on securities in which it may invest or on indices comprised of such securities and may purchase and write call and put options on such contracts.

A financial futures contract is a contract to buy or sell a specified quantity of financial instruments such as U.S. Treasury bills, notes and bonds at a specified future date at a price agreed upon when the contract is made. An index futures contract is a contract to buy or sell specified units of an index at a specified future date at a price agreed upon when the contract is made. The value of a unit is based on the current value of the index. Under such contracts no delivery of the actual securities making up the index takes place. Rather, upon expiration of the contract, settlement is made by exchanging cash in an amount equal to the difference between the contract price and the closing price of the index at expiration, net of variation margin previously paid. Substantially all futures contracts are closed out before settlement date or called for cash settlement. A futures contract is closed out by buying or selling an identical offsetting futures contract. Upon entering into a futures contract, an Index Fund is required to deposit an initial margin with the futures broker. The initial margin serves as a "good faith" deposit that an Index Fund will honor its futures commitments. Subsequent payments (called "variation margin") to and from the broker are made on a daily basis as the price of the underlying investment fluctuates.

Options on futures contracts give the purchaser the right to assume a position in a futures contract at a specified price at any time before expiration of the option. Each Index Fund will not commit more than 5% of the market value of its total assets to initial margin deposits on futures and premiums paid for options on futures.

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Illiquid Securities

Each Fund may invest in illiquid securities. Each Index Fund will invest no more than 15% of its net assets, and each Money Market Fund will invest no more than 10% of its net assets, in illiquid securities or securities that are not readily marketable, including repurchase agreements and time deposits of more than seven days' duration. The absence of a regular trading market for illiquid securities imposes additional risks on investments in these securities. Illiquid securities may be difficult to value and may often be disposed of only after considerable expense and delay.

Lending of Fund Securities

Each Index Fund has the authority to lend portfolio securities to brokers, dealers and other financial organizations in amounts up to 33 1/3% of the total value of its assets. Any such loan must be continuously secured by collateral in cash or cash equivalents maintained on a current basis in an amount at least equal to the market value of the securities loaned by an Index Fund. An Index Fund would continue to receive the equivalent of the interest or dividends paid by the issuer on the securities loaned, and would receive an additional return that may be in the form of a fixed fee or a percentage of the collateral. An Index Fund would have the right to call the loan and obtain the securities loaned at any time on notice of not more than five business days. In the event of bankruptcy or other default of the borrower, an Index Fund could experience both delays in liquidating the loan collateral or recovering the loaned securities and losses including (a) possible decline in the value of collateral or in the value of the securities loaned during the period while the Fund seeks to enforce its rights thereto, (b) possible sub-normal levels of income and lack of access to income during this period, and (c) expenses of enforcing its rights.

Options on Securities and Securities Indices

Each Index Fund may purchase or sell options on securities in which it may invest and on indices that are comprised of securities in which it may invest, subject to the limitations set forth above and provided such options are traded on a national securities exchange or in the over-the-counter market. Options on securities indices are similar to options on securities except there is no transfer of a security and settlement is in cash. A call option on a securities index grants the purchaser of the call, for a premium paid to the seller, the right to receive in cash an amount equal to the difference between the closing value of the index and the exercise price of the option times a multiplier established by the exchange upon which the option is traded. Typically, a call option will be profitable to the holder of the option if the value of the security or the index increases during the term of the option; a put option will be valuable if the value of the security or the index decreases during the term of the option. The Index Funds may also invest in warrants, which entitle the holder to buy equity securities at a specific price for a specific period of time.

Purchase of Other Investment Company Shares

Each Fund may, to the extent permitted under the Investment Company of 1940, as amended (the "1940 Act") and exemptive rules and orders thereunder, invest in shares of other investment companies which invest exclusively in money market instruments or in investment companies with investment policies and objectives which are substantially similar to the Fund's. These investments may be made temporarily, for example, to invest uncommitted cash balances or, in limited circumstances, to assist in meeting shareholder redemptions.

Repurchase Agreements

Each Fund may enter into repurchase agreements with banks and other financial institutions, such as broker-dealers. In substance, a repurchase agreement is a loan for which the Fund receives securities as collateral. Under a repurchase agreement, the Fund purchases securities from a financial institution that agrees to repurchase the securities at the Fund's original purchase price plus interest within a specified time (normally one business day). The Fund will limit repurchase transactions to those member banks of the Federal Reserve System and broker-dealers whose creditworthiness the Adviser considers satisfactory. Should the counterparty to a transaction fail financially, the Fund may encounter delay and incur costs before being able to sell the securities, or may be prevented from realizing on the securities. Further, the amount realized upon the sale of the securities may be less than that necessary to fully compensate the Fund.

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Section 4(2) Commercial Paper/Rule 144A Securities

Each Fund may also invest in commercial paper issued in reliance on the private placement exemption from registration afforded by Section 4(2) of the Securities Act of 1933, as amended ("1933 Act") ("Section 4(2) paper") or in securities that that can be offered and sold only to "qualified institutional buyers" under Rule 144A of the 1933 Act ("Rule 144A securities").

Section 4(2) paper is restricted as to disposition under the federal securities laws and generally is sold to institutional investors that agree that they are purchasing the paper for investment and not with a view to public distribution. Any resale by the purchaser must be in an exempt transaction.
Section 4(2) paper normally is resold to other institutional investors like the Funds through or with the assistance of the issuer or investment dealers that make a market in Section 4(2) paper. Rule 144A securities generally must be sold only to other qualified institutional buyers.

Section 4(2) paper and Rule 144A securities will not be subject to each Fund's percentage limitations on illiquid securities when the Adviser (pursuant to guidelines adopted by the Board of Trustees) determines that a liquid trading market exists. There can be no assurance that a liquid trading market will exist at any time for either Section 4(2) paper or Rule 144A securities.

U.S. Government Securities

Each Fund may purchase U.S. government securities. The types of U.S. government obligations in which each Fund may at times invest include: (1) a variety of U.S. Treasury obligations, which differ only in their interest rates, maturities and times of issuance; and (2) obligations issued or guaranteed by U.S. government agencies and instrumentalities which are supported by any of the following: (a) the full faith and credit of the U.S. Treasury, (b) the right of the issuer to borrow an amount limited to a specific line of credit from the U.S. Treasury, (c) discretionary authority of the U.S. government agency or instrumentality, or (d) the credit of the instrumentality (examples of agencies and instrumentalities are: Federal Land Banks, Federal Housing Administration, Federal Farm Credit Bank, Farmers Home Administration, Export-Import Bank of the United States, Central Bank for Cooperatives, Federal Intermediate Credit Banks, Federal Home Loan Banks, General Services Administration, Maritime Administration, Tennessee Development Bank, Asian-American Development Bank, International Bank for Reconstruction and Development and Federal National Mortgage Association). No assurance can be given that in the future the U.S. government will provide financial support to such U.S. government agencies or instrumentalities described in (2)(b), (2)(c) and (2)(d), other than as set forth above, since it is not obligated to do so by law.

The Money Funds may purchase U.S. government obligations on a forward commitment basis. The Money Funds may also purchase Treasury Inflation-Protection Securities, a type of inflation-indexed Treasury security. Treasury Inflation Protected Securities provide for semiannual payments of interest and a payment of principal at maturity which are adjusted for changes in the Consumer Price Index for All Urban Consumers ("CPI-U").

When-Issued Securities

Each Fund may purchase securities on a when-issued basis. Delivery of and payment for these securities may take place as long as a month or more after the date of the purchase commitment. The value of these securities is subject to market fluctuation during this period, and no income accrues to the Fund until settlement takes place. The Fund segregates liquid securities in an amount at least equal to these commitments. For the purpose of determining the adequacy of these securities, the segregated securities will be valued at market. If the market value of such securities declines, additional cash or securities will be segregated on the Fund's records on a daily basis so that the market value of the account will equal the amount of such commitments by the Fund. When entering into a when-issued transaction, the Fund will rely on the other party to consummate the transaction; if the other party fails to do so, the Fund may be disadvantaged. The Money Funds will not invest more than 25% of their respective net assets in when-issued securities.

Securities purchased on a when-issued basis and held by a Fund are subject to changes in market value based upon the public's perception of changes in the level of interest rates. Generally, the value of such securities

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will fluctuate inversely to changes in interest rates -- i.e., they will appreciate in value when interest rates decline and decrease in value when interest rates rise. Therefore, if in order to achieve higher interest income a Fund remains substantially fully invested at the same time that it has purchased securities on a "when-issued" basis, there will be a greater possibility of fluctuation in the Fund's net asset value ("NAV").

When payment for when-issued securities is due, a Fund will meet its obligations from then-available cash flow, the sale of segregated securities, the sale of other securities or, and although it would not normally expect to do so, from the sale of the when-issued securities themselves (which may have a market value greater or less than the Fund's payment obligation). The sale of securities to meet such obligations carries with it a greater potential for the realization of capital gains, which are subject to federal income taxes.

Reverse Repurchase Agreements

The Aggregate Bond Index Fund and the Money Funds may enter into reverse repurchase agreements under the circumstances described in "Investment Restrictions." In substance, a reverse repurchase agreement is a borrowing for which the Fund provides securities as collateral. Under a reverse repurchase agreement, the Fund sells portfolio securities to a financial institution in return for cash in an amount equal to a percentage of the portfolio securities' market value and agrees to repurchase the securities at a future date at a prescribed repurchase price equal to the amount of cash originally received plus interest on such amount. A Fund retains the right to receive interest and principal payments with respect to the securities while they are in the possession of the financial institutions. Cash or liquid high-quality debt obligations from a Fund's portfolio equal in value to the repurchase price including any accrued interest will be segregated by the Fund's custodian on the Fund's records while a reverse repurchase agreement is in effect. Reverse repurchase agreements involve the risk that the market value of securities sold by a Fund may decline below the price at which it is obligated to repurchase the securities. Reverse repurchase agreements also involve a risk of default by the counterparty, which may adversely affect a Fund's ability to reacquire the underlying securities.

Total Return Swaps

The Aggregate Bond Index Fund may contract with a counterparty to pay a stream of cash flows and receive the total return of an index or a security for purposes of attempting to obtain a particular desired return at a lower cost to the Fund than if the Fund had invested directly in an instrument that yielded that desired return. A Fund's return on a swap will depend on the ability of its counterparty to perform its obligations under the swap. The Adviser will cause the Fund to enter into swap agreements only with counterparties that would be eligible for consideration as repurchase agreement counterparties under the Fund's repurchase agreement guidelines.

Eurodollar Certificates of Deposit ("ECDs"), Eurodollar Time Deposits ("ETDs") and Yankee Certificates of Deposit ("YCDs")

The Aggregate Bond Index Fund and the Money Funds may invest in ECDs, ETDs and YCDs. ECDs and ETDs are U.S. dollar denominated certificates of deposit issued by foreign branches of domestic banks and foreign banks. YCDs are U.S. dollar denominated certificates of deposit issued by U.S. branches of foreign banks.

Different risks than those associated with the obligations of domestic banks may exist for ECDs, ETDs and YCDs because the banks issuing these instruments, or their domestic or foreign branches, are not necessarily subject to the same regulatory requirements that apply to domestic banks, such as loan limitations, examinations and reserve, accounting, auditing, recordkeeping and public reporting requirements. Obligations of foreign issuers also involve risks such as future unfavorable political and economic developments, withholding tax, seizures of foreign deposits, currency controls, interest limitations, and other governmental restrictions that might affect repayment of principal or payment of interest, or the ability to honor a credit commitment.

Forward Commitments

The Aggregate Bond Index Fund and the Money Funds may contract to purchase securities for a fixed price at a future date beyond customary settlement time. When effecting such transactions, cash or marketable securities held by a Fund of a dollar amount sufficient to make payment for the securities to be purchased will be segregated

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on a Fund's records at the trade date and maintained until the transaction is settled. The failure of the other party to complete the transaction may cause the Fund to miss an advantageous price or yield. Forward commitments involve risk of loss if the value of the security to be purchased declines prior to settlement date, or if the other party fails to complete the transaction.

Interest Rate Swaps

The Aggregate Bond Index Fund may enter into interest rate swap transactions with respect to any security it is entitled to hold. Interest rate swaps involve the exchange by the Aggregate Bond Index Fund with another party of their respective rights to receive interest, e.g., an exchange of floating rate payments for fixed rate payments. The Aggregate Bond Index Fund expects to enter into these transactions primarily to preserve a return or spread on a particular investment or portion of its portfolio or to protect against any increase in the price of securities it anticipates purchasing at a later date. The Aggregate Bond Index Fund intends to use these transactions as a hedge and not as a speculative investment.

Investment-Grade Bonds

The Aggregate Bond Index Fund and the Liquid Reserves Fund may invest in corporate notes and bonds that are rated investment-grade by a Nationally Recognized Statistical Rating Organization ("NRSRO") (and, in the case of the Liquid Reserves Fund, rated in one of the two short-term highest rating categories by at least two NRSROs or by one NRSRO if only one NRSRO has rated the security) or, if unrated, are of comparable quality to the rated securities described above, as determined by the Adviser , in accordance with procedures established by the Board of Trustees. Investment-grade securities include securities rated Baa by Moody's or BBB- by S&P (and securities of comparable quality), which have speculative characteristics.

Asset-Backed Securities

The Aggregate Bond Index Fund and the Liquid Reserves Fund may invest in asset-backed securities. Asset-backed securities represent undivided fractional interests in pools of instruments, such as consumer loans, and are similar in structure to mortgage-related securities described below. Payments of principal and interest are passed through to holders of the securities and are typically supported by some form of credit enhancement, such as a letter of credit, surety bond, limited guarantee by another entity or by priority to certain of the borrower's other securities. The degree of credit enhancement varies, generally applying only until exhausted and covering only a fraction of the security's par value. If the credit enhancement of an asset-backed security held by a Fund has been exhausted, and if any required payments of principal and interest are not made with respect to the underlying loans, the Fund may experience loss or delay in receiving payment and a decrease in the value of the security. Use of asset-backed securities will represent less than 5% of the Liquid Reserves Fund's total assets by issuer.

Mortgage-Backed and Mortgage-Related Securities

The Aggregate Bond Index Fund and the Money Funds may invest in mortgage pass-through certificates. Mortgage pass-through certificates are issued by governmental, government-related and private organizations and are backed by pools of mortgage loans. These mortgage loans are made by savings and loan associations, mortgage bankers, commercial banks and other lenders to home buyers throughout the United States. The securities are "pass-through" securities because they provide investors with monthly payments of principal and interest that, in effect, are a "pass-through" of the monthly payments made by the individual borrowers on the underlying mortgage loans, net of any fees paid to the issuer or guarantor of the pass-through certificates. The principal governmental issuer of such securities is the Government National Mortgage Association ("GNMA"), which is a wholly-owned U.S. government corporation within the Department of Housing and Urban Development. Government-related issuers include the Federal Home Loan Mortgage Corporation ("FHLMC"), which is a shareholder-owned government-sponsored enterprise established by Congress, and the Federal National Mortgage Association ("FNMA"), a government sponsored corporation owned entirely by private stockholders. Commercial banks, savings and loan associations, private mortgage insurance companies, mortgage bankers and other secondary market issuers also create pass-through pools of conventional residential mortgage loans. Such issuers may be the originators of the underlying mortgage loans as well as the guarantors of the mortgage-related securities.

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1. GNMA Mortgage Pass-Through Certificates ("Ginnie Maes"). Ginnie Maes represent an undivided interest in a pool of mortgage loans that are insured by the Federal Housing Administration or the Farmers Home Administration or guaranteed by the Veterans Administration. Ginnie Maes entitle the holder to receive all payments (including prepayments) of principal and interest owed by the individual mortgagors, net of fees paid to GNMA and to the issuer which assembles the loan pool and passes through the monthly mortgage payments to the certificate holders (typically, a mortgage banking firm), regardless of whether the individual mortgagor actually makes the payment. Because payments are made to certificate holders regardless of whether payments are actually received on the underlying loans, Ginnie Maes are of the "modified pass-through" mortgage certificate type. GNMA is authorized to guarantee the timely payment of principal and interest on the Ginnie Maes as securities backed by an eligible pool of mortgage loans. The GNMA guaranty is backed by the full faith and credit of the United States, and GNMA has unlimited authority to borrow funds from the U.S. Treasury to make payments under the guaranty. The market for Ginnie Maes is highly liquid because of the size of the market and the active participation in the secondary market by securities dealers and a variety of investors.

2. FHLMC Mortgage Participation Certificates ("Freddie Macs"). Freddie Macs represent interests in groups of specified first lien residential conventional mortgage loans underwritten and owned by FHLMC. Freddie Macs entitle the holder to timely payment of interest, which is guaranteed by FHLMC. FHLMC guarantees either ultimate collection or timely payment of all principal payments on the underlying mortgage loans. In cases where FHLMC has not guaranteed timely payment of principal, FHLMC may remit the amount due on account of its guarantee of ultimate payment of principal at any time after default on an underlying loan, but in no event later than one year after it becomes payable. Freddie Macs are not guaranteed by the United States or by any of the Federal Home Loan Banks and do not constitute a debt or obligation of the United States or of any Federal Home Loan Bank. The secondary market for Freddie Macs is highly liquid because of the size of the market and the active participation in the secondary market by FHLMC, securities dealers and a variety of investors.

3. FNMA Guaranteed Mortgage Pass-Through Certificates ("Fannie Maes"). Fannie Maes represent an undivided interest in a pool of conventional mortgage loans secured by first mortgages or deeds of trust, on one-family to four-family residential properties. FNMA is obligated to distribute scheduled monthly installments of principal and interest on the loans in the pool, whether or not received, plus full principal of any foreclosed or otherwise liquidated loans. The obligation of FNMA under its guaranty is solely the obligation of FNMA and is not backed by, nor entitled to, the full faith and credit of the United States.

Privately issued mortgage-backed securities, including collateralized mortgage obligations, may have characteristics similar to those described above, but do not have the backing of the U.S. government or any agency or instrumentality. Certain "tranches" of mortgage pools may represent an interest in only a portion of the interest or principal payments paid on the underlying mortgages, and these values may be highly volatile.

The market value of mortgage-related securities depends on, among other things, the level of interest rates, the certificates' coupon rates and the payment history of the underlying borrowers.

Although the mortgage loans in a pool underlying a mortgage pass-through certificate will have maturities of up to 30 years, the average life of a mortgage pass-through certificate will be substantially less because the loans will be subject to normal principal amortization and also may be prepaid prior to maturity. Prepayment rates vary widely and may be affected by changes in mortgage interest rates. In periods of falling interest rates, the rate of prepayment on higher interest rate mortgages tends to increase, thereby shortening the actual average life of the mortgage pass-through certificate. Conversely, when interest rates are rising, the rate of prepayment tends to decrease, thereby lengthening the average life of the mortgage pass-through certificate. Accordingly, it is not possible to predict accurately the average life of a particular pool. Reinvestment of prepayments may occur at higher or lower rates than the original yield on the certificates. Due to the prepayment feature and the need to reinvest prepayments of principal at current rates, mortgage pass-through certificates with underlying loans bearing interest rates in excess of the market rate can be less effective than typical noncallable bonds with similar maturities at "locking in" yields during periods of declining interest rates, although they may have comparable risks of declining in value during periods of rising interest rates.

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Mortgage-Backed Security Rolls

The Aggregate Bond Index Fund may enter into "forward roll" transactions with respect to mortgage-backed securities issued by GNMA, FNMA or FHLMC. In a forward roll transaction, the Fund will sell a mortgage security to a dealer or other permitted entity and simultaneously agree to repurchase a similar security from the institution at a later date at an agreed upon price. The mortgage securities that are repurchased will bear the same interest rate as those sold, but generally will be collateralized by different pools of mortgages with different prepayment histories than those sold. There are two primary risks associated with the roll market for mortgage-backed securities. First, the value and safety of the roll depends entirely upon the counterparty's ability to redeliver the security at the termination of the roll. Therefore, the counterparty to a roll must meet the same credit criteria as the Fund's repurchase agreement counterparties. Second, the security which is redelivered at the end of the roll period must be substantially the same as the initial security, i.e., it must have the same coupon, be issued by the same agency and be of the same type, have the same original stated term to maturity, be priced to result in similar market yields and must be "good delivery." Within these parameters, however, the actual pools that are redelivered could be less desirable than those originally rolled, especially with respect to prepayment characteristics.

Variable and Floating Rate Securities

The Aggregate Bond Index Fund and the Money Funds may invest in variable and floating rate securities. A variable rate security provides for the automatic establishment of a new interest rate on set dates. Interest rates on these securities are ordinarily tied to, and are a percentage of, a widely recognized interest rate, such as the yield on 90-day U.S. Treasury bills or the prime rate of a specified bank. These rates may change as often as twice daily. Generally, changes in interest rates will have a smaller effect on the market value of variable and floating rate securities than on the market value of comparable fixed income obligations. Thus, investing in variable and floating rate securities generally allows less opportunity for capital appreciation and depreciation than investing in comparable fixed income securities. Variable rate obligations whose interest is readjusted no less frequently than annually will be deemed to have a maturity equal to the period remaining until the next readjustment of the interest rate.

Zero Coupon Securities

The Aggregate Bond Index Fund and the Money Funds may invest in zero coupon securities. Zero coupon securities are notes, bonds and debentures that: (1) do not pay current interest and are issued at a substantial discount from par value; (2) have been stripped of their unmatured interest coupons and receipts; or (3) pay no interest until a stated date one or more years into the future. These securities also include certificates representing interests in such stripped coupons and receipts. Generally, changes in interest rates will have a greater impact on the market value of a zero coupon security than on the market value of the comparable securities that pay interest periodically during the life of the instrument. In order to satisfy a requirement for qualification as a "regulated investment company" under the Internal Revenue Code of 1986, as amended (the "Code"), the Aggregate Bond Index Fund and the Money Funds must distribute at least 90% of their net investment income, including the original issue discount accrued on zero coupon bonds. Because the Funds will not receive cash payments on a current basis from the issuer in respect of accrued original discount, the Funds may have to distribute cash obtained from other sources in order to satisfy the 90% distribution requirement. Such cash might be obtained from selling other portfolio holdings of the Funds. In some circumstances such sales might be necessary in order to satisfy cash distribution requirements even though investment considerations might otherwise make it undesirable for the Funds to sell such securities at such time.

The Money Funds may invest no more than 25% of their respective total assets in stripped securities that have been stripped by their holder, typically a custodian bank or investment brokerage firm. A number of securities firms and banks have stripped the interest coupons and resold them in custodian receipt programs with different names such as Treasury Income Growth Receipts ("TIGRS") and Certificates of Accrual on Treasuries ("CATS"). Privately-issued stripped securities such as TIGRS and CATS are not themselves guaranteed by the U.S. government, but the future payment of principal or interest on U.S. Treasury obligations which they represent is so guaranteed.

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Variable Amount Master Demand Notes

The Money Funds may invest in variable amount master demand notes which are unsecured obligations that are redeemable upon demand and are typically unrated. These instruments are issued pursuant to written agreements between their issuers and holders. The agreements permit the holders to increase (subject to an agreed maximum) and the holders and issuers to decrease the principal amount of the notes, and specify that the rate of interest payable on the principal fluctuates according to an agreed formula. Generally, changes in interest rates will have a smaller effect on the market value of these securities than on the market value of comparable fixed income obligations. Thus, investing in these securities generally allows less opportunity for capital appreciation and depreciation than investing in comparable fixed income securities. There may be no active secondary market with respect to a particular variable rate instrument.

Investment Restrictions

The Portfolios in which the Funds invest each have substantially the same investment restrictions as their corresponding Funds. In reviewing the description of a Fund's investment restrictions below, you should assume that the investment restrictions of the corresponding Portfolio are the same in all material respects as those of the Fund.

The Trust has adopted the following restrictions applicable to the Index Funds, which may not be changed without the affirmative vote of a "majority of the outstanding voting securities" of a Fund, which is defined in the 1940 Act, to mean the affirmative vote of the lesser of (1) more than 50% of the outstanding shares of the Fund and (2) 67% or more of the shares present at a meeting if more than 50% of the outstanding shares are present at the meeting in person or by proxy.

Each Index Fund may not:

(1) Borrow more than 33 1/3% of the value of its total assets less all liabilities and indebtedness (other than such borrowings).

(2) Underwrite securities issued by other persons except to the extent that, in connection with the disposition of its portfolio investments, it may be deemed to be an underwriter under certain federal securities laws.

(3) Purchase or sell real estate, although it may purchase securities of issuers which deal in real estate, securities which are secured by interests in real estate, and securities which represent interests in real estate, and it may acquire and dispose of real estate or interests in real estate acquired through the exercise of its rights as a holder of debt obligations secured by real estate or interests therein.

(4) Purchase or sell commodities or commodity contracts, except that it may purchase and sell financial futures contracts and options and may enter into foreign exchange contracts and other financial transactions not involving the direct purchase or sale of physical commodities.

(5) Make loans, except by purchase of debt obligations in which the Fund may invest consistent with its investment policies, by entering into repurchase agreements, or by lending its portfolio securities.

(6) With respect to 75% of its total assets, invest in the securities of any issuer if, immediately after such investment, more than 5% of the total assets of the Fund (taken at current value) would be invested in the securities of such issuer; provided that this limitation does not apply to obligations issued or guaranteed as to interest or principal by the U.S. government or its agencies or instrumentalities, or to securities issued by other investment companies.

(7) With respect to 75% of its total assets, acquire more than 10% of the outstanding voting securities of any issuer, provided that such limitation does not apply to securities issued by other investment companies.

(8) Purchase securities (other than securities of the U.S. government, its agencies or instrumentalities), if, as a result of such purchase, more than 25% of the Fund's total assets would be invested in any one industry.

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(9) Issue any class of securities which is senior to the Fund's shares, to the extent prohibited by the Investment Company Act of 1940, as amended.

In addition, it is contrary to each Index Fund's present policy, which may be changed without shareholder approval, to invest in (a) securities which are not readily marketable, (b) securities restricted as to resale (excluding securities determined by the Trustees of the Trust (or the person designated by the Trustees of the Trust to make such determinations) to be readily marketable), and (c) repurchase agreements maturing in more than seven days, if, as a result, more than 15% of the Fund's net assets (taken at current value) would be invested in securities described in (a), (b) and (c) above.

The Trust has also adopted the following fundamental investment policies, which, with respect to the Money Funds, may not be changed without the approval of a majority of the shareholders of the respective Fund, as defined above. Each Money Fund will not:

(1) Invest 25% or more of the value of its total assets in securities of companies primarily engaged in any one industry (other than the U.S. government, its agencies and instrumentalities). Concentration may occur as a result of changes in the market value of portfolio securities, but may not result from investment. Foreign and domestic branches of U.S. and foreign banks are not considered a single industry for purposes of this restriction.

(2) Borrow money, except as a temporary measure for extraordinary or emergency purposes or to facilitate redemptions (not for leveraging or investment), provided that borrowings do not exceed an amount equal to 33 1/3% of the current value of the Fund's assets taken at market value, less liabilities other than borrowings. If at any time the Fund's borrowings exceed this limitation due to a decline in net assets, such borrowings will within three days be reduced to the extent necessary to comply with this limitation. The Fund will not purchase investments once borrowed funds (including reverse repurchase agreements) exceed 5% of its total assets.

(3) Pledge, mortgage or hypothecate its assets. However, the Fund may pledge securities having a market value (on a daily marked-to-market basis) at the time of the pledge not exceeding 33 1/3% of the value of the Fund's total assets to secure borrowings permitted by paragraph
(2) above.

(4) Invest in securities of any one issuer (other than securities issued by the U.S. government, its agencies, and instrumentalities or securities issued by other investment companies), if immediately after and as a result of such investment the current market value of the Fund's holdings in the securities of such issuer exceeds 5% of the value of the Fund's assets and to not more than 10% of the outstanding voting securities of such issuer.

(5) Make loans to any person or firm; provided, however, that the making of a loan shall not include: (i) the acquisition for investment of bonds, debentures, notes or other evidences of indebtedness of any corporation or government which are publicly distributed or of a type customarily purchased by institutional investors, or (ii) the entry into "repurchase agreements." The Fund may lend its portfolio securities to broker-dealers or other institutional investors if the aggregate value of all securities loaned does not exceed 33 1/3% of the value of the Fund's total assets.

(6) Invest more than 10% of its net assets in the aggregate, on an ongoing basis, in illiquid securities or securities that are not readily marketable, including repurchase agreements and time deposits of more than seven days' duration.

(7) Engage in the business of underwriting securities issued by others, except that the Fund will not be deemed to be an underwriter or to be underwriting on account of the purchase of securities subject to legal or contractual restrictions on disposition.

(8) Issue senior securities, except as permitted by its investment objective, policies and restrictions, and except as permitted by the 1940 Act.

The concentration policy of the Liquid Reserves Fund (as set forth in Investment Restriction No. 1, above) permits the Liquid Reserves Fund to invest, without limit, in bankers' acceptances, certificates of deposit and similar instruments issued by: (i) U.S. banks, (ii) U.S. branches of foreign banks (in circumstances in which the U.S. branches of foreign banks are subject to the same regulation as U.S. banks), (iii) foreign branches of U.S. banks (in circumstances in which the Liquid Reserves Fund will have recourse to the U.S. bank for the obligations of the

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foreign branch), and (iv) foreign branches of foreign banks to the extent that the Adviser determines that the foreign branches of foreign banks are subject to the same or substantially similar regulations as U.S. banks. The Liquid Reserves Fund may concentrate in such instruments when, in the opinion of the Adviser, the yield, marketability and availability of investments meeting the Liquid Reserves Fund's quality standards in the banking industry justify any additional risks associated with the concentration of the Fund's assets in such industry. To the extent these restrictions reflect matters of operating policy which may be changed without shareholder vote, these restrictions may be amended upon approval by the Board of Trustees and notice to shareholders. If a percentage restriction is adhered to at the time of investment, a subsequent increase or decrease in a percentage resulting from a change in the values of assets will not constitute a violation of that restriction, except as otherwise noted.

All percentage limitations on investments will apply at the time of the making of an investment and shall not be considered violated unless an excess or deficiency occurs or exists immediately after and as a result of such investment. Except for the investment restrictions listed above as fundamental or to the extent designated as such in the Prospectus with respect to a Fund, the other investment policies described in this Statement or in the Prospectus are not fundamental and may be changed by approval of the Trustees.

Disclosure of Portfolio Holdings

Introduction

Each Fund currently invests all of its assets in a related Portfolio, each of which is a series of State Street Master Funds ("Master Trust"), that has the same investment objectives and substantially the same investment policies as the relevant Fund. The Master Trust and the Trust, on behalf of each of their series (collectively, the "Trusts"), have adopted a joint portfolio holdings disclosure policy (the "Policy").

The Trusts disclose to the general public the complete schedule of portfolio holdings of their respective Portfolios or Funds for the second and fourth fiscal quarters on Form N-CSR, and for the first and third fiscal quarters on Form N-Q, within 60 days of the end of the respective quarter, by filing the applicable Form with the Securities and Exchange Commission (the "SEC").

General Policy

In general, the Policy provides that portfolio holdings may be disclosed by the Trusts on a selective basis only by an officer of the Trusts or a member of the Adviser's compliance department ("Authorizing Officer") where it is determined that (i) there is a legitimate business purpose for the information,
(ii) recipients are subject to a duty of confidentiality, including a duty not to trade on the nonpublic information; and (iii) disclosure is in the best interests of Fund shareholders. The Authorizing Officer shall attempt to uncover any apparent conflict between the interests of Fund shareholders on the one hand and those of the Adviser, the Fund's underwriter and their affiliates on the other. For example, an Authorizing Officer may inquire whether a portfolio manager of a Fund has entered into any special arrangements with the requestor to share confidential portfolio holdings information in exchange for a substantial investment in the Funds or other products managed by the portfolio manager. Any potential conflicts between shareholders and affiliated persons of the Funds that arise as a result of a request for portfolio holdings information shall be evaluated by the Authorizing Officer in the best interests of shareholders.

The Policy provides that portfolio holdings information for the Funds may be made available more frequently and prior to its public availability in accordance with the foregoing to:

1. Unaffiliated Service Providers. Various firms, such as pricing services, proxy voting services, financial printers, pricing information vendors, third parties that deliver analytical, statistical, or consulting services, and other unaffiliated third parties that provide services and may require portfolio holdings information to provide services to the Funds. The frequency with which portfolio holdings may be disclosed to an Unaffiliated Service Provider, and the length of the time delay, if any, between the date of the information and the date on which the information is disclosed to the Unaffiliated Service Provider, is determined based on the facts and circumstances surrounding the disclosure, including, without limitation, the nature of the portfolio holdings information to be disclosed, the risk of harm to the Funds and their shareholders, and the legitimate business purposes served by such

14

disclosure. The frequency of disclosure to an Unaffiliated Service Provider varies and may be as frequent as daily, with no time delay. In general, the Funds' contractual arrangements with Unaffiliated Service Providers subject them to a duty of confidentiality. Each of the Funds' Unaffiliated Service Providers as of the date of this SAI for which the Funds may provide portfolio holdings information is identified in the Funds' Prospectus and this SAI; in addition, Bowne, Inc. (financial printer) is an Unaffiliated Service Provider.

2. Ratings and Rankings Agencies. Organizations that publish ratings and/or rankings of the Funds. The table below sets forth the names of those organizations as of the date of this SAI to whom the Funds (or the Master Trust on behalf of the Funds) may provide portfolio holdings information on a monthly or quarterly basis within one to ten business days after the end of the period:

NAME

Bloomberg L.P.

Lipper Analytical Services

Moody's Investors Service Morningstar, Inc.
Standard & Poor's Ratings Services Thomson Financial

3. Fund Affiliates and Fiduciaries. Various firms, such as (1) the Adviser, State Street Bank and Trust Company ("State Street") and its affiliates (in their capacities as administrator, transfer agent and custodian) and the distributor to a Fund; and (2) an accounting firm, an auditing firm, or outside legal counsel retained by the Adviser, an affiliate of the Adviser, or a Fund. The frequency with which portfolio holdings may be disclosed to Fund Affiliates and Fiduciaries, and the length of the time delay, if any, between the date of the information and the date on which the information is disclosed to the Fund Affiliates and Fiduciaries, is determined based on the facts and circumstances surrounding the disclosure, including, without limitation, the nature of the portfolio holdings information to be disclosed, the risk of harm to the Funds and their shareholders, and the legitimate business purposes served by such disclosure. The frequency of disclosure to Fund Affiliates and Fiduciaries varies and may be as frequent as daily, with no lag.

4. As Required by Law. Any party as required by applicable laws, rules, and regulations. Examples of such required disclosures include, but are not limited to, disclosure of Fund portfolio holdings (1) in a filing or submission with the SEC or another regulatory body (including, without limitation, filings by the Adviser and its affiliates on Schedules 13D, 13G and 13F), (2) upon the request of the SEC or another regulatory body, (3) in connection with a lawsuit, or
(4) as required by court order.

5. Waiver. Any other party, for a legitimate business purpose, upon waiver or exception, with the consent of the Trust's officers, which will be disclosed to the Board of Trustees no later than its next regularly scheduled quarterly meeting.

Prohibitions on Disclosure of Portfolio Holdings

The Policy provides that portfolio managers and other senior officers or spokespersons of the Adviser, State Street or the Trusts may disclose or confirm the ownership of any individual portfolio holding position to reporters, brokers, shareholders, consultants or other interested persons only if such information has been previously publicly disclosed in accordance with the Policy. For example, the Adviser may indicate that a Fund owns XYZ Company only if the Fund's ownership of such company has previously been publicly disclosed.

Additional Matters

None of the Funds, the Adviser, State Street or any other party may receive compensation or other consideration in connection with the disclosure of information about portfolio securities. The Trust's Board of Trustees has approved the Policy, and will review any material changes to the Policy, and will periodically review persons or entities receiving non-public disclosure.

15

MANAGEMENT OF THE TRUST

The Trustees are responsible for generally overseeing the Trust's business. The following table provides biographical information with respect to each Trustee and officer of the Trust. As of April 28, 2006, none of the Trustees were considered to be an "interested person" of the Trust, as that term is defined in the 1940 Act (the "Independent Trustees").

                                                                                           NUMBER OF
                                                                                            FUNDS IN
                                                                                              FUND
    NAME, ADDRESS,      POSITION(S)   TERM OF OFFICE                                      COMPLEX (1)        OTHER
  AND DATE OF BIRTH      HELD WITH     AND LENGTH OF         PRINCIPAL OCCUPATION           OVERSEEN     DIRECTORSHIPS
       ("DOB")             TRUST       TIME SERVED          DURING PAST FIVE YEARS         BY TRUSTEE   HELD BY TRUSTEE
  -----------------     -----------   --------------   --------------------------------   -----------   ---------------
INDEPENDENT TRUSTEES

Michael F. Holland
Holland & Company,      Trustee and   Term:            Chairman, Holland & Company             12       Trustee, State
LLC                     Chairman of   Indefinite       L.L.C. (investment adviser)                      Street Master
375 Park Avenue         the Board                      (1995 - present).                                Funds;
New York, NY 10152                    Elected: 7/99                                                     Director, the
                                                                                                        Holland Series
DOB: July 7, 1944                                                                                       Fund, Inc.; and
                                                                                                        Director, The
                                                                                                        China Fund,
                                                                                                        Inc.

William L. Boyan
State Street Master     Trustee       Term:            Trustee of Old Mutual South             12       Trustee, State
Funds                                 Indefinite       Africa Master Trust                              Street Master
P.O. Box 5049                                          (investments) (1995 - present);                  Funds; and
Boston, MA 02206                      Elected: 7/99    Chairman emeritus, Children's                    Trustee, Old
                                                       Hospital (1984 - present);                       Mutual South
DOB: January 20, 1937                                  Director, Boston Plan For                        Africa Master
                                                       Excellence (non-profit) (1994 -                  Trust
                                                       present); President and Chief
                                                       Operations Officer, John
                                                       Hancock Mutual Life Insurance
                                                       Company (1959 - 1999). Mr.
                                                       Boyan retired in 1999.

Rina K. Spence
7 Acacia Street         Trustee       Term:            President of SpenceCare                 12       Trustee, State
Cambridge, MA 02138                   Indefinite       International LLC (1998 -                        Street Master
                                                       present); Member of the                          Funds;
DOB: October 24, 1948                 Elected: 7/99    Advisory Board, Ingenium Corp.                   Director,
                                                       (technology company) (2001 -                     Berkshire Life
                                                       present); Chief Executive                        Insurance
                                                       Officer, IEmily.com (internet                    Company of
                                                       company) (2000 - 2001); Chief                    America; and
                                                       Executive Officer of Consensus                   Director,
                                                       Pharmaceutical, Inc. (1998 -                     IEmily.com
                                                       1999); Founder, President and
                                                       Chief Executive Officer of
                                                       Spence Center for Women's
                                                       Health (1994 - 1998); Trustee,
                                                       Eastern Enterprise (utilities)
                                                       (1988 - 2000).

Douglas T. Williams
State Street Master     Trustee       Term:            Executive Vice President of             12       Trustee, State
Funds                                 Indefinite       Chase Manhattan Bank (1987 -                     Street Master
P.O. Box 5049                                          1999). Mr. Williams retired in                   Funds
Boston, MA 02206                      Elected: 7/99    1999.

DOB: December 23,
1940

16

                                                                                           NUMBER OF
                                                                                            FUNDS IN
                                                                                              FUND
    NAME, ADDRESS,      POSITION(S)   TERM OF OFFICE                                      COMPLEX (1)        OTHER
  AND DATE OF BIRTH      HELD WITH     AND LENGTH OF         PRINCIPAL OCCUPATION           OVERSEEN     DIRECTORSHIPS
       ("DOB")             TRUST       TIME SERVED          DURING PAST FIVE YEARS         BY TRUSTEE   HELD BY TRUSTEE
  -----------------     -----------   --------------   --------------------------------   -----------   ---------------
OFFICERS:

James E. Ross                                          President, SSgA Funds                   --              --
SSgA Funds              President     Term:            Management, Inc. (2005 -
Management, Inc.                      Indefinite       present); Principal, SSgA Funds
State Street                                           Management, Inc. (2001 -
Financial Center                      Elected: 4/05    present); Principal, State
One Lincoln Street                                     Street Global Advisers (March
Boston, MA 02111-2900                                  2000 - present).

DOB: June 24, 1965

Gary L. French                                                                                 --              --
State Street Bank and   Treasurer     Term:            Senior Vice President of State
Trust Company                         Indefinite       Street Bank and Trust Company
2 Avenue de Lafayette                                  (2002 - present); Managing
Boston, MA 02111                      Elected: 5/05    Director, Deutsche Bank
                                                       (including its predecessor,
DOB: July 4, 1951                                      Scudder Investments), Fund
                                                       Operations Unit (2001 - 2002);
                                                       President, UAM Fund Services
                                                       (1995 - 2001).

Ryan M. Louvar                                                                                 --              --
State Street Bank       Secretary     Term:            Vice President and Counsel of
and Trust Company                     Indefinite       State Street Bank and Trust
2 Avenue de Lafayette                                  Company (2005 - present);
Boston, MA 02111                      Elected: 4/06    Counsel, BISYS Fund Services
                                                       (2000 to 2005).

DOB: February 18,
1972

Peter A. Ambrosini      Chief         Term:                                                    --              --
SSgA Funds              Compliance    Indefinite       Senior Principal and Chief
Management, Inc.        Officer                        Compliance and Risk Management
State Street                          Elected: 5/04    Officer, SSgA Funds Management,
Financial Center                                       Inc. and State Street Global
One Lincoln Street                                     Advisors (2001-present);
Boston, MA 02111                                       Managing Director,
                                                       PricewaterhouseCoopers LLP
DOB: December 17,                                      (1986-2001).
1943

(1) The "Fund Complex" consists of six series of the Trust discussed herein and six series of State Street Master Funds, which are not discussed in this SAI and are offered by a separate prospectus and SAI.

The By-Laws of the Trust provide that the Trust shall indemnify each person who is or was a Trustee of the Trust against all expenses, judgments, fines, settlements and other amounts actually and reasonably incurred in connection with any proceedings if the person in good faith and reasonably believes that his or her conduct was in the Trust's best interest. The Trust, at its expense, provides liability insurance for the benefit of its Trustees and officers.

17

Standing Committees

The Board of Trustees has established various committees to facilitate the timely and efficient consideration of all matters of importance to Independent Trustees, the Trust, and the Trust's shareholders and to facilitate compliance with legal and regulatory requirements. Currently, the Board has created an Audit Committee, Nominating Committee and Pricing Committee.

The Audit Committee is composed of all of the Independent Trustees. The Audit Committee meets twice a year, or more often as required, in conjunction with meetings of the Board of Trustees. The Audit Committee oversees and monitors the Trust's internal accounting and control structure, its auditing function and its financial reporting process. The Audit Committee is responsible for selecting and retaining the independent accountants for the Trust. The Audit Committee is responsible for approving the audit plans, fees and other material arrangements in respect of the engagement of the independent accountants, including non-audit services performed. The Audit Committee reviews the qualifications of the independent accountant's key personnel involved in the foregoing activities and monitors the independent accountant's independence. During the fiscal year ended December 31, 2005, the Audit Committee held two meetings.

The Nominating Committee is composed of all of the Independent Trustees. The Nominating Committee is responsible for nominating for election as Trustees all Trustee candidates. The Nominating Committee will consider nominees to the Board of Trustees recommended by shareholders. Recommendations should be submitted to the Nominating Committee in care of the Secretary of the Trust. The Nominating Committee meets as is required. During the fiscal year ended December 31, 2005, the Nominating Committee did not meet.

The Pricing Committee is composed of all of the Independent Trustees. The Pricing Committee is responsible for the valuation and revaluation of any portfolio investments for which market quotations or sale prices are not readily available in accordance with the Trust's Valuation Procedures. The Pricing Committee acts pursuant to a tiered notification and meeting structure as set forth in the Valuation Procedures, and is generally convened in the event of a pricing matter that may potentially materially impact a Fund's NAV. During the fiscal year ended December 31, 2005, the Pricing Committee did not meet.

Trustee Ownership of Securities of the Trust, Adviser and Distributor

As of December 31, 2005 none of the Independent Trustees had any ownership of securities of the Adviser or ALPS Distributors, Inc. ("ALPS"), the Trust's distributor, or any person directly or indirectly controlling, controlled by or under common control with the Adviser or ALPS.

The following table sets forth information describing the dollar range of equity securities beneficially owned by each Trustee in the Trust as of December 31, 2005.

                                                Aggregate Dollar Range of Equity Securities
                                                   in All Registered Investment Companies
                       Dollar Range of Equity   Overseen by Trustee in Family of Investment
  Name of Trustee     Securities in the Trust                    Companies
  ---------------     -----------------------   -------------------------------------------
William L. Boyan                None                                None
Michael F. Holland              None                                None
Rina K. Spence                  None                                None
Douglas T. Williams             None                                None

18

Trustee Compensation

The following table sets forth the total remuneration of Trustees and officers of the Trust for the fiscal year ended December 31, 2005.

                                                  Pension or
                                                  Retirement                          Total Compensation
                                 Aggregate         Benefits        Estimated Annual    from Trust & Fund
                               Compensation   Accrued as Part of     Benefits Upon      Complex Paid to
      Name and Position         from Trust      Trust Expenses        Retirement           Trustees
      -----------------        ------------   ------------------   ----------------   ------------------
William L. Boyan, Trustee           $0                $0                  $0                $30,000
Michael F. Holland, Trustee         $0                $0                  $0                $30,000
Rina K. Spence, Trustee             $0                $0                  $0                $30,000
Douglas T. Williams, Trustee        $0                $0                  $0                $30,000

The Trust, the Adviser and ALPS have adopted codes of ethics (the "Codes of Ethics") under Rule 17j-1 of the 1940 Act. The Codes of Ethics permit personnel, subject to the Codes of Ethics and their provisions, to invest in securities, including securities that may be purchased or held by the Trust, Adviser, State Street or ALPS.

PROXY VOTING PROCEDURES

The Trust has adopted proxy voting procedures pursuant to which the Trust delegates the responsibility for voting proxies relating to portfolio securities held by the Portfolios to the Adviser as part of the Adviser's general management of the Portfolios, subject to the Board's continuing oversight. A copy of the Trust's proxy voting procedures is located in Appendix B and a copy of the Adviser's proxy voting procedures is located in Appendix C.

Shareholders may receive information regarding how the Funds voted proxies relating to portfolio securities during the most recent 12-month period ending June 30 (i) by calling (877) 521-4083 or (ii) on the SEC's website at www.sec.gov.

CONTROL PERSONS AND PRINCIPAL HOLDERS OF SECURITIES

As of April 3, 2006, the Trustees and officers of the Trust owned in the aggregate less than 1% of the shares of the Funds of the Trust (all series taken together).

As of April 3, 2006, to the knowledge of the Trust, the following persons held of record or beneficially through one or more accounts 5% or more of the outstanding shares of any class of the Funds.

                     Name and Address                       Percentage
                     ----------------                       ----------
State Street Equity 500 Index Fund -Administrative Shares
   American United Life Insurance Company                      99.97%
   One American Square
   Indianapolis, IN 46282

State Street Equity 500 Index Fund - Service Shares
   Nationwide Trust Company                                    49.58%
   P.O. Box 182029
   Columbus, OH 43218-2029

   Calvert Distributors, Inc.                                  24.43%
   4550 Montgomery Ave., Suite 100N
   Bethesda, MD

   Nationwide Insurance Company                                16.71%
   P.O. Box 182029
   Columbus, OH 43218-2029

19

State Street Equity 500 Index Fund -Class R Shares
   American United Life Insurance Company                     100.00%
   One American Square
   Indianapolis, IN 46282

State Street Institutional Liquid Reserves Fund
   State Street Inst Liquid Reserves                          100.00%
   P.O. Box 5049
   Boston, MA

Persons or organizations owning 25% or more of the outstanding shares of a Fund may be presumed to "control" (as that term is defined in the 1940 Act) a Fund. As a result, these persons or organizations could have the ability to approve or reject those matters submitted to the shareholders of such Fund for their approval.

INVESTMENT ADVISORY AND OTHER SERVICES

Investment Advisory Agreements

SSgA Funds Management, Inc. ("SSgA FM" or the "Adviser") is responsible for the investment management of the Funds pursuant to an Investment Advisory Agreement dated May 1, 2001 (the "Advisory Agreement"), by and between the Adviser and the Trust.

Each Fund currently invests all of its assets in a related Portfolio that has the same investment objectives and substantially the same investment policies as the relevant Fund. As long as a Fund remains completely invested in a Portfolio (or any other investment company), the Adviser is not entitled to receive any investment advisory fee with respect to the Fund. A Fund may withdraw its investment from the related Portfolio at any time if the Trust's Board of Trustees determines that it is in the best interests of the Fund and its shareholders to do so. The Trust has retained the Adviser as investment adviser to manage a Fund's assets in the event that the Fund withdraws its investment from its related Portfolio.

The Adviser is also the investment adviser to each of the related Portfolios pursuant to an investment advisory agreement (the "Portfolio Advisory Agreement") between the Adviser and State Street Master Funds, on behalf of the Portfolios. The Adviser receives an investment advisory fee with respect to each related Portfolio. The Portfolio Advisory Agreement is the same in all material respects as the Advisory Agreement between the Trust on behalf of the Funds and the Adviser. Each Fund that invests in a related Portfolio bears a proportionate part of the management fees paid by the Portfolio (based on the percentage of the Portfolio's assets attributable to the Fund).

The Advisory Agreement will continue from year to year provided that a majority of the Trustees and a majority of the Independent Trustees or a majority of the shareholders of the Trust approve its continuance. The Advisory Agreement may be terminated by the Adviser or the Trust without penalty upon sixty days' notice and will terminate automatically upon its assignment. The Advisory Agreement was most recently approved by the Trustees, including a majority of the Independent Trustees, on November 16, 2005.

The Adviser and its affiliates may have deposit, loan and other commercial banking relationships with the issuers of obligations that may be purchased on behalf of the Funds, including outstanding loans to such issuers that could be repaid in whole or in part with the proceeds of securities so purchased. Such affiliates deal, trade and invest for their own accounts in such obligations and are among the leading dealers of various types of such obligations. The Adviser has informed the Funds that, in making its investment decisions, it will not obtain or use material inside information in its possession or in the possession of any of its affiliates. In making investment recommendations for a Fund, the Adviser will not inquire or take into consideration whether an issuer of securities proposed for purchase or sale by the Fund is a customer of the Adviser, its parent or its subsidiaries or affiliates and, in dealing with its customers, the Adviser, its parent, subsidiaries and affiliates will not inquire or take into consideration whether securities of such customers were held by any Fund managed by the Adviser or any such affiliate.

In certain instances there may be securities that are suitable for a Fund as well as for one or more of the Adviser's other clients. Investment decisions for the Trust and for the Adviser's other clients are made with a view

20

to achieving their respective investment objectives. It may develop that a particular security is bought or sold for only one client even though it might be held by, or bought or sold for, other clients. Likewise, a particular security may be bought for one or more clients when one or more clients are selling that same security. Some simultaneous transactions are inevitable when several clients receive investment advice from the same investment adviser, particularly when the same security is suitable for the investment objectives of more than one client. When two or more clients are simultaneously engaged in the purchase or sale of the same security, the securities are allocated among clients in a manner believed to be equitable to each. It is recognized that in some cases this system could have a detrimental effect on the price or volume of the security as far as the Fund is concerned. However, it is believed that the ability of each Fund to participate in volume transactions will produce better executions for the Funds.

Portfolio Managers

The following persons serve as the portfolio managers of each operational non-money market Portfolio as of the date of this SAI. The following table lists the number and types of accounts managed by each individual and assets under management in those accounts as of December 31, 2005:

                          REGISTERED                   POOLED                                                  TOTAL
                          INVESTMENT      ASSETS     INVESTMENT      ASSETS                      ASSETS        ASSETS
 PORTFOLIO                  COMPANY      MANAGED       VEHICLE      MANAGED        OTHER        MANAGED       MANAGED*
  MANAGER     PORTFOLIO    ACCOUNTS    ($BILLIONS)    ACCOUNTS    ($BILLIONS)     ACCOUNTS    ($BILLIONS)   ($BILLIONS)
 ---------    ---------   ----------   -----------   ----------   -----------   -----------   -----------   -----------
Michael       Equity
   Feehily    500 Index     2 funds        $7.4        5 funds       $17.1      12 accounts       $9.8        $34.3
John Tucker   Equity
              500 Index     9 funds         1.2        4 funds         4.4       7 accounts       $8.7         14.3

* The total number of accounts and assets have been allocated to each respective manager. Therefore, some accounts and assets have been counted twice.

As indicated in the table above, portfolio managers at the Adviser may manage numerous accounts for multiple clients. These accounts may include registered investment companies (which include exchange-traded funds), other types of pooled accounts (e.g., collective investment funds), and separate accounts (i.e., accounts managed on behalf of individuals or public or private institutions). Portfolio managers make investment decisions for each account based on the investment objectives and policies and other relevant investment considerations applicable to that portfolio. The portfolio managers do not beneficially own any shares of any Portfolio as of December 31, 2005.

When a portfolio manager has responsibility for managing more than one account, potential conflicts of interest may arise. Those conflicts may arise out of: (a) the portfolio manager's execution of different investment strategies for various accounts; or (b) the allocation of resources or investment opportunities.

A potential conflict of interest may arise as a result of the portfolio managers' responsibility for multiple accounts with similar investment guidelines. Under these circumstances, a potential investment may be suitable for more than one of the portfolio manager's accounts, but the quantity of the investment available for purchase is less than the aggregate amount the accounts would ideally devote to the opportunity. Similar conflicts may arise when multiple accounts seek to dispose of the same investment. The portfolio manager may also manage accounts whose objectives and policies differ from that of the respective Portfolio. These differences may be such that under certain circumstances, trading activity appropriate for one account managed by the portfolio manager may have adverse consequences for another account managed by the portfolio manager. For example, an account may sell a significant position in a security, which could cause the market price of that security to decrease, while the fund maintained its position in that security.

A potential conflict may arise when the portfolio manager is responsible for accounts that have different advisory fees. The difference in fees could create an incentive for the portfolio manager to favor one account over another, for example, in terms of access to investment opportunities. This conflict may be heightened if an account is subject to a performance-based fee. Another potential conflict may arise when the portfolio manager has an

21

investment in one or more accounts that participates in transactions with other accounts. His or her investment(s) may create an incentive for the portfolio manager to favor one account over another. The Adviser has adopted policies and procedures reasonably designed to address these potential material conflicts. For instance, portfolio managers within the Adviser are normally responsible for all accounts within a certain investment discipline and do not, absent special circumstances, differentiate among the various accounts when allocating resources. Additionally, the Adviser and its advisory affiliates have processes and procedures for allocating investment opportunities among portfolios that are designed to provide a fair and equitable.

The compensation of the Adviser's investment professionals is based on a number of factors. The first factor considered is external market. Through extensive compensation survey process, the Adviser seeks to understand what its competitors are paying people to perform similar roles. This data is then used to determine a competitive baseline in the areas of base pay, bonus, and long term incentive (i.e. equity). The second factor taken into consideration is the size of the pool available for this compensation. The Adviser is a part of State Street Corporation, and therefore works within its corporate environment on determining the overall level of its incentive compensation pool. Once determined, this pool is then allocated to the various locations and departments of the Adviser and its affiliates. The discretionary determination of the allocation amounts to these locations and departments is influenced by the competitive market data, as well as the overall performance of the group. The pool is then allocated on a discretionary basis to individual employees based on their individual performance. There is no fixed formula for determining these amounts, nor is anyone's compensation directly tied to the investment performance or asset value of a product or strategy. The same process is followed in determining incentive equity allocations.

Administrator, Custodian and Transfer Agent

Under the Administrative Services Agreement (the "Administration Agreement"), State Street is obligated on a continuous basis to provide such administrative services as the Board of Trustees of the Trust reasonably deems necessary for the proper administration of the Trust and the Funds. State Street will generally assist in all aspects of the Trust's and the Funds' operations; supply and maintain office facilities (which may be in State Street's own offices); provide statistical and research data, data processing services, clerical, accounting, bookkeeping and record keeping services (including without limitation the maintenance of such books and records as are required under the 1940 Act and the rules thereunder, except as maintained by other agents), internal auditing, executive and administrative services, and stationery and office supplies; prepare reports to shareholders or investors; prepare and file tax returns; supply financial information and supporting data for reports to and filings with the SEC and various state Blue Sky authorities; supply supporting documentation for meetings of the Board of Trustees; provide monitoring reports and assistance regarding compliance with Declarations of Trust, by-laws, the Funds' investment objectives and policies and with Federal and state securities laws; arrange for appropriate insurance coverage; calculate NAVs, net income and realized capital gains or losses; and negotiate arrangements with, and supervise and coordinate the activities of, agents and others to supply services. Pursuant to the Administration Agreement, the Trust has agreed to a limitation on damages and to indemnify the Administrator for certain liabilities, including certain liabilities arising under federal securities laws, unless such loss or liability results from the Administrator's gross negligence or willful misconduct in the performance of its duties.

State Street serves as Custodian for the Funds pursuant to the Custody Agreement and holds the Funds' assets.

State Street also serves as Transfer Agent of the Funds (except the Liquid Reserves Fund) pursuant to the Transfer Agency and Service Agreement.

Fees

As consideration for State Street's services as administrator, transfer agent and custodian to the Index Funds and the U.S. Government Fund, and for State Street's assumption of the ordinary expenses of those Funds, State Street shall be entitled to receive from each Index Fund and the U.S. Government Fund an annual fee, accrued daily at the rate of 1/365th of the applicable fee rate and payable monthly on the first business day of each month, of the following annual percentages of each Index Fund's and the U.S. Government Fund's average daily net assets during the month:

22

                                      Annual percentage of
Index Fund                          average daily net assets
----------                          ------------------------
Equity 500 Index Fund
   - Administrative Shares                    0.05%
   - Service Shares                           0.05%
   - Class R Shares                           0.05%
Equity 400 Index Fund                         0.10%
Equity 2000 Index Fund                        0.10%
Aggregate Bond Index Fund                     0.10%
U.S. Government Money Market Fund             0.05%

As consideration for State Street's services as administrator and custodian to the Liquid Reserves Fund, State Street shall receive from the Liquid Reserves Fund an annual fee, accrued daily at the rate of 1/365th and payable monthly on the first business day of each month, pursuant to the following schedule:

Annual Fee Schedule for the Liquid Reserves Fund $25,000 for Administration Services $12,000 for Custody and Accounting Services

Prior to February 1, 2005, State Street also served as transfer agent to the Liquid Reserves Fund for which it received $30,000 for Transfer Agency Services (plus transaction fees of $5.00 per manual trade and $2.00 per automated trade). Effective February 1, 2005, ALPS Mutual Funds Services, Inc. serves as Transfer Agent to the Liquid Reserves Fund.

SSgA FM has contractually agreed to cap the total operating expenses of the Liquid Reserves Fund (not including the pass-through expenses of its corresponding Portfolio) at 0.05% of the Fund's average daily net assets until April 30, 2006. For the year ended December 31, 2005, SSgA FM reimbursed the Liquid Reserves Fund $282,635 under this agreement. For the period from August 12, 2004 (commencement of operations of the Liquid Reserves Fund) through December 31, 2004, SSgA FM reimbursed the Liquid Reserves Fund $97,420 under this agreement.

The administration, custodian and transfer agency fees accrued for the last three fiscal years are set forth in the table below.

                        Fiscal year ended   Fiscal year ended   Fiscal year ended
Fund                    December 31, 2003   December 31, 2004   December 31, 2005
----                    -----------------   -----------------   -----------------
Equity 500 Index Fund        $90,826             $134,853            $110,265
Liquid Reserves Fund         $    --             $ 26,004*           $ 64,823

* The Fund commenced operations on August 12, 2004.

Rule 12b-1 Plan

The Trust has adopted a distribution plan pursuant to Rule 12b-1 (the "Rule 12b-1 Plan") under which the Funds may compensate their distributor (or others) for services in connection with the distribution of the Funds' shares and for services provided to Fund shareholders. As of April 28, 2006 none of the Independent Trustees or interested persons of the Trust had a direct or indirect financial interest in the operation of the Rule 12b-1 Plan. The Rule 12b-1 Plan calls for payments at an annual rate (based on average net assets) as follows:

State Street Equity 500 Index Fund - Administrative Shares:   0.15%
State Street Equity 500 Index Fund - Service Shares:          0.25%
State Street Equity 500 Index Fund - Class R Shares:          0.60%
State Street Equity 400 Index Fund:                           0.25%
State Street Equity 2000 Index Fund:                          0.25%
State Street Aggregate Bond Index Fund:                       0.25%
Liquid Reserves Fund:                                         0.05%
U.S. Government Money Market Fund:                            0.05%

23

Shareholder servicing fees paid to the Distributor pursuant to the Rule 12b-1 Plan for the last fiscal year are reflected in the chart below.

                           Fiscal year ended
Fund                       December 31, 2005
----                       -----------------
Equity 500 Index Fund
   Administrative Shares        $286,942
   Service Shares               $ 73,060
   Class R Shares               $     54*
Liquid Reserves Fund            $401,339

* Class R Shares of the Equity 500 Index Fund commenced operations on June 7, 2005.

Counsel and Independent Registered Public Accounting Firm

Ropes & Gray LLP serves as counsel to the Trust. The principal business address of Ropes & Gray LLP is One International Place, Boston, Massachusetts 02110.

Ernst & Young LLP serves as the independent registered public accounting firm for the Trust and provides (i) audit services and (ii) assistance and consultation with respect to the preparation of filings with the SEC. In connection with the audit of the 2005 financial statements, the Trust entered into an engagement agreement with Ernst & Young LLP that sets forth the terms of Ernst & Young's audit engagement. That agreement is subject to alternative dispute resolution procedures and a mutual exclusion of punitive damages. The principal business address of Ernst & Young LLP is 200 Clarendon St., Boston, Massachusetts 02116.

BROKERAGE ALLOCATION AND OTHER PRACTICES

The Funds invests all of their investable assets in a corresponding Portfolio and therefore do not directly incur transactional costs for purchases and sales of portfolio investments. The Funds purchase and redeem shares of the corresponding Portfolio each day depending on the number of shares of such Fund purchased or redeemed by investors on that day. Shares of the Portfolios are available for purchase by the Funds at their NAV without any sales charges, transaction fees, or brokerage commissions being charged.

All portfolio transactions are placed on behalf of the Portfolios by SSgA FM. Purchases and sales of securities on a securities exchange are effected through brokers who charge a commission for their services. Ordinarily commissions are not charged on over the counter orders (i.e. debt securities and money market investments) because a Portfolio pays a spread which is included in the cost of the security, and is the difference between the dealer's cost and the cost to a Portfolio. When a Portfolio executes an over the counter order with an electronic communications network, an alternative trading system or a non-market maker, a commission is charged because there is no spread on the trade. Securities may be purchased from underwriters at prices that include underwriting fees. The Money Portfolios and the Aggregate Bond Index Portfolio normally do not pay a stated brokerage commission on transactions.

Each Portfolio's investment advisory agreement authorizes SSgA FM to place, in the name of the Portfolio, orders for the execution of the securities transactions in which the Portfolio is authorized to invest, provided SSgA FM seeks the best overall terms for the transaction. In selecting brokers or dealers (including affiliates of SSgA FM), SSgA FM chooses the broker-dealer deemed most capable of providing the services necessary to obtain the most favorable execution (the most favorable cost or net proceeds reasonably obtainable under the circumstances). The full range of brokerage services applicable to a particular transaction may be considered when making this judgment, which may include, but is not limited to: liquidity, price, commission, timing, aggregated trades, capable floor brokers or traders, competent block trading coverage, ability to position, capital strength and stability, reliable and accurate communications and settlement processing, use of automation, knowledge of other buyers or sellers, arbitrage skills, administrative ability, underwriting, and provision of information on a particular security or market in which the transaction is to occur. The specific criteria will vary depending on the nature of the transaction, the

24

market in which it is executed, and the extent to which it is possible to select from among multiple broker-dealers. SSgA FM does not currently use any Portfolio's assets for soft-dollar arrangements. SSgA FM does not presently participate in any soft dollar arrangements. It may aggregate trades with clients of State Street Global Advisors whose commission dollars are used to generate soft dollar credits. Although SSgA FM's clients' commissions are not used for soft dollars, the clients may benefit from the soft dollar products/services received by State Street Global Advisors.

The Adviser assumes general supervision over placing orders on behalf of the Trust for the purchase or sale of portfolio securities.

CAPITAL STOCK AND OTHER SECURITIES

Under the Declaration of Trust, the Trustees are authorized to issue an unlimited number of shares of each Fund. Upon liquidation or dissolution of a Fund, investors are entitled to share pro rata in the Fund's net assets available for distribution to its investors. Investments in a Fund have no preference, preemptive, conversion or similar rights and are fully paid and non-assessable, except as set forth below. Investments in a Fund may not be transferred.

Each investor is entitled to a vote in proportion to the number of Fund shares it owns. Shares do not have cumulative voting rights, and investors holding more than 50% of the aggregate outstanding shares in the Trust may elect all of the Trustees if they choose to do so. The Trust is not required and has no current intention to hold annual meetings of investors but the Trust will hold special meetings of shareholders when in the judgment of the Trustees it is necessary or desirable to submit matters for a shareholder vote.

Under Massachusetts law, shareholders in a Massachusetts business trust could, under certain circumstances, be held personally liable for the obligations of the trust. However, the Declaration of Trust disclaims shareholder liability for acts or obligations of the Trust and provides for indemnification out of the Trust's property for any claim or liability to which the shareholder may become subject by reason of being or having been a shareholder and for reimbursement of the shareholder for all legal and other expenses reasonably incurred by the shareholder in connection with any such claim or liability. Thus the risk of a shareholder incurring financial loss on account of shareholder liability is limited to circumstances in which the Trust would be unable to meet its obligations.

PURCHASE, REDEMPTION AND PRICING OF SHARES

Shares of the Funds are offered continuously at a price equal to the NAV attributable to each share. Each Fund determines the NAV per share on each day on which the New York Stock Exchange (the "NYSE") is open for trading ("Business Day"). This determination is made each Business Day at the close of regular trading on the NYSE (the "Valuation Time") by dividing the value of the Index Fund's net assets (i.e., the value of its securities and other assets less its liabilities, including expenses payable or accrued) by the number of shares outstanding at the time the determination is made.

The NYSE is open for trading every weekday except for: (a) the following holidays: New Year's Day, Martin Luther King, Jr.'s Birthday, Washington's Birthday (the third Monday in February), Good Friday, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and Christmas; and (b) the preceding Friday or the subsequent Monday when one of the calendar-determined holidays falls on a Saturday or Sunday, respectively. Purchases and withdrawals will be effected at the time of determination of NAV next following the receipt of any purchase or withdrawal order which is determined to be in good order.

It is the Money Funds' policy to use their best efforts to attempt to maintain a constant price per share of $1.00 respectively, although there can be no assurance that the $1.00 NAV per share will be maintained. In accordance with this effort and pursuant to Rule 2a-7 under the 1940 Act, each Money Market Fund uses the amortized cost valuation method to value its portfolio instruments. This method involves valuing an instrument at its cost and thereafter assuming a constant amortization to maturity of any discount or premium, even though the portfolio security may increase or decrease in market value generally in response to changes in interest rates. While

25

this method provides certainty in valuation, it may result in periods during which value, as determined by amortized cost, is higher or lower than the price each Money Market Fund would receive if it sold the instrument.

For example, in periods of declining interest rates, the daily yield on each Money Market Fund's shares computed by dividing the annualized daily income on the Fund's portfolio by the NAV based upon the amortized cost valuation technique may tend to be higher than a similar computation made by using a method of valuation based upon market prices and estimates. In periods of rising interest rates, the daily yield on each Money Market Fund's shares computed the same way may tend to be lower than a similar computation made by using a method of calculation based upon market prices and estimates.

The Trustees have established procedures reasonably designed to stabilize each Money Market Fund's price per share at $1.00. These procedures include: (1) the determination of the deviation from $1.00, if any, of each Money Market Fund's NAV using market values; (2) periodic review by the Trustees of the amount of and the methods used to calculate the deviation; and (3) maintenance of records of such determination. The Trustees will promptly consider what action, if any, should be taken if such deviation exceeds 1/2 of one percent.

The Funds' securities will be valued pursuant to guidelines established by the Board of Trustees.

TAXATION OF THE FUNDS

Qualification as a Regulated Investment Company

Each Fund intends to qualify each year as a regulated investment company under Subchapter M of the Code. In order to qualify for the favorable tax treatment accorded regulated investment companies, each Fund must, among other things, (i) derive at least 90% of its gross income from dividends, interest, payments with respect to certain securities loans, gains from the sale of securities or foreign currencies, or other income (including, but not limited to, gains from options, futures or forward contracts) derived with respect to its business of investing in such stock, securities or currencies; (ii) distribute with respect to each taxable year at least 90% of the sum of its taxable net investment income, its tax-exempt income and the excess, if any, of net short-term capital gains over net long-term capital losses for each year; and (iii) diversify its holdings so that at the end of each fiscal quarter (a) at least 50% of the value of its total assets are invested in cash, U.S. government securities, securities of other regulated investment companies, and other securities of issuers which represent, with respect to each issuer, no more than 5% of the value of the Fund's total assets and 10% of the outstanding voting securities of such issuer, and (b) not more than 25% of its assets are invested in the securities (other than those of the U.S. government or other regulated investment companies) of any one issuer or of two or more issuers which the Fund controls and which are engaged in the same, similar or related trades and businesses. To the extent it qualifies for treatment as a regulated investment company, the Fund will not be subject to federal income tax on income paid to its shareholders in the form of dividends or capital gain distributions.

An excise tax at the rate of 4% will be imposed on the excess, if any, of each Fund's "required distribution" over its actual distributions in any calendar year. Generally, the "required distribution" is 98% of the Fund's ordinary income for the calendar year plus 98% of its capital gain net income recognized during the one-year period ending October 31 (or December 31, if the Fund so elects) plus undistributed amounts from prior years. Each Fund intends to make distributions sufficient to avoid imposition of the excise tax. Distributions declared by a Fund during October, November and December to shareholders of record on a date in any such month and paid by the Fund during the following January will be treated for federal tax purposes as paid by the Fund and received by shareholders on December 31 of the year in which declared.

Taxation of Distributions Received by Shareholders

Shareholders of each Fund will be subject to federal income taxes on distributions made by the Fund whether received in cash or additional shares of the Fund. Distributions by each Fund of net income and short-term capital gains, if any, will be taxable to shareholders as ordinary income. Distributions designated by a Fund as deriving from net gains on securities held for more than one year will generally be taxable to shareholders as long-term capital gain (generally taxed at 15% rate for non-corporate shareholders), without regard to how long a shareholder has held shares of the Fund.

26

Dividends and distributions on a Fund's shares are generally subject to federal income tax as described herein even though such dividends and distributions may economically represent a return of a particular shareholder's investment. Such distributions are likely to occur in respect of shares purchased at a time when a Fund's NAV reflects gains that are either unrealized or realized but not distributed. Such realized gains may be required to be distributed even when a Fund's NAV also reflects unrealized losses.

Taxation of Certain Financial Instruments

Each Index Fund may enter into futures contracts, options on futures contracts and options on securities indices. Such contracts held by the Index Fund at the close of its taxable year will generally be treated for federal income tax purposes as sold for their fair market value on the last business day of such year, a process known as "marking-to-market." Forty percent of any gain or loss resulting from this constructive sale will be treated as short-term capital gain or loss and 60 percent of such gain or loss will be treated as long-term capital gain or loss without regard to the period the Index Fund actually held the instruments. The amount of any capital gain or loss actually realized by the Index Fund in a subsequent sale or other disposition of the instruments is adjusted to reflect any capital gain or loss taken into account in a prior year as a result of the constructive sale of the instruments. The hedging transactions undertaken by the Index Fund may result in "straddles" for federal income tax purposes. The straddle rules may affect the character of gains or losses realized by an Index Fund. In addition, losses realized by the Index Fund on positions that are part of a straddle may be deferred under the straddle rules, rather than being taken into account in calculating the taxable income for the taxable year in which the losses are realized.

An Index Fund may make one or more of the elections available under the Code that are applicable to straddles. If an Index Fund makes any of the elections, the amount, character and timing of the recognition of gains and losses from the affected straddle positions will be determined under the rules that vary according to the election(s) made. The rules applicable under certain of the elections may operate to accelerate the recognition of gains or losses from the affected straddle positions. Because the straddle rules may affect the character of gains or loses, defer losses and/or accelerate the recognition of gains or losses from the affected straddle positions, the amount which may be reported to investors and which will be taxable to them as ordinary income or long-term capital gain, may be increased or decreased as compared to an Index Fund that did not engage in such hedging transactions.

Foreign Income

Income received by a Fund from sources within foreign countries may be subject to withholding and other foreign taxes. Tax conventions between certain countries and the United States may reduce or eliminate such taxes. It is impossible to determine the effective rate of foreign tax in advance since the amount of a Fund's assets to be invested in various countries will vary. If a Fund is liable for foreign taxes, and if more than 50% of the value of the Fund's total assets at the close of its taxable year consists of stocks or securities of foreign corporations, the Fund may make an election pursuant to which certain foreign taxes paid by it would be treated as having been paid directly by its shareholders. Pursuant to such election, the Fund's share of the amount of foreign taxes paid by it will be included in the income of its shareholders, and such shareholders (except tax-exempt shareholders) may, subject to certain limitations, claim either a credit or deduction for the taxes. Each Fund's investors will be notified after the close of a Fund's taxable year as to the foreign taxes that will "pass through" for that year and, if so, such notification will designate (a) the regulated investment company investor's portion of the foreign taxes paid to each such country and (b) the portion which represents income derived form sources within each such country.

The amount of foreign taxes for which an investor may claim a credit in any year will generally be subject to a separate limitation for "passive income," which includes, among other items of income, dividends, interests and certain foreign currency gains. Because capital gains realized by a Fund on the sale of foreign securities will be treated as U.S.-source income, the available credit for foreign taxes paid with respect to such gains may be restricted by this limitation. In addition a shareholder must hold shares of a Fund (without protection from risk or loss) on the ex-dividend date and for at least 16 days during the 30-day period beginning on the date that is 15 days before the ex-dividend date in order to be eligible to claim a foreign tax credit passed through by the Fund.

27

The Aggregate Bond Index Fund's Investments in Original Issue Discount Securities

The Aggregate Bond Index Fund's investment in securities issued at a discount and certain other obligations will (and investments in securities purchased at a discount may) require the Fund to accrue and distribute income not yet received. In such cases, the Aggregate Bond Index Fund may be required to sell assets (including when it is not advantageous to do so) to generate the cash necessary to distribute as dividends to its shareholders all of its income and gains and therefore to eliminate any tax liability at the Fund level.

Redemptions and Exchanges

Redemptions and exchanges of each Fund's shares are taxable events and, accordingly, shareholders may realize gain or loss on these transactions. In general, any gain realized upon a taxable disposition of shares will be treated as long-term capital gain if the shares have been held for more than one year. Otherwise, the gain on the sale, exchange or redemption of Fund shares will be treated as short-term capital gain. However, if a shareholder sells Fund shares at a loss within six months after purchasing the shares, the loss will be treated as a long-term capital loss to the extent of any long-term capital gain distributions received by the shareholder. Furthermore, no loss will be allowed on the sale of Fund shares to the extent the shareholder acquired other shares of the same Fund within 30 days prior to the sale of the loss shares or 30 days after such sale.

The foregoing discussion summarizes some of the consequences under the current federal tax law of an investment in the Funds. It is not a substitute for personal tax advice. Consult your personal tax advisor about the potential tax consequences of an investment in the Fund including in-kind transactions under all applicable tax laws.

Non-U.S. investors in the Funds should consult their tax advisors concerning the tax consequences of ownership of shares in the Funds, including the possibility that distributions may be subject to a 30 percent United States withholding tax (or a reduced rate of withholding provided by treaty). Some investors may be subject to a withholding tax on distributions of ordinary income, capital gains and any cash received on redemption of shares in the Funds, which is currently 28%. Generally, investors subject to backup withholding will be those for whom no certified taxpayer identification number is on file with the Trust or who, to the Trust's knowledge, have furnished an incorrect number. When establishing an account, an investor must certify under penalty of perjury that such number is correct and that such investor is not otherwise subject to backup withholding.

UNDERWRITER

ALPS Distributors, Inc. serves as the Funds' Distributor (the "Distributor") pursuant to the Distribution Agreement by and between the Distributor and the Trust. Pursuant to the Distribution Agreement, the Funds pay the Distributor fees under the Rule 12b-1 Plan in effect for the Funds. For a description of the fees paid to the Distributor under the Rule 12b-1 Plan, see "Rule 12b-1 Plan," above. The Distributor is not obligated to sell any specific number of shares and will sell shares of a Fund on a continuous basis only against orders to purchase shares. The principal business address of the Distributor is 1625 Broadway, Suite 2200, Denver, Colorado 80202.

CALCULATION OF PERFORMANCE DATA

Money Funds:

The yield for each Money Market Fund is calculated daily based upon the seven days ending on the date of calculation ("base period"). The yields are computed by determining the net change, exclusive of capital changes and income other than investment income, in the value of a hypothetical pre-existing account having a balance of one share at the beginning of the base period, subtracting a hypothetical charge reflecting deductions from shareholder accounts and dividing the net change in the account value by the value of the account at the beginning of the base period to obtain the base period return, and then multiplying the base period return by (365/7) with the resulting yield figure carried to the nearest hundredth of one percent.

Each Money Fund calculates an effective yield by determining the net change, exclusive of capital changes and income other than investment income, in the value of a hypothetical pre-existing account having a balance of one share at the beginning of the period, subtracting a hypothetical charge reflecting deductions from shareholder

28

accounts, and dividing the difference by the value of the account at the beginning of the base period to obtain the base period return, and then compounding the base period return by adding 1, raising the sum to a power equal to 365 divided by 7, and subtracting 1 from the result, according to the following formula:

EFFECTIVE YIELD=[(BASE PERIOD RETURN+1)[365/7]] - 1

Each Money Fund calculates its tax equivalent current yield by dividing that portion of a Fund's yield, as described above, that is tax-exempt by 1 minus a stated income tax rate and adding the quotient to that portion, if any, of the Fund's yield that is not tax-exempt.

Each Money Fund calculates its tax equivalent effective yield by dividing that portion of a Fund's effective yield, as described above, that is tax-exempt by 1 minus a stated income tax rate and adding the quotient to that portion, if any, of the Fund's effective yield that is not tax-exempt.

All Funds:

Average Annual Total Return

The Funds' "average annual total return" figures are computed according to a formula prescribed by the SEC. The formula can be expressed as follows:

P(1+T)(n) = ERV

Where:

P    =  a hypothetical initial payment of $1000.
T    =  average annual total return.
n    =  number of years.
ERV  =  Ending Redeemable Value of a hypothetical $1,000 payment
        made at the beginning of the 1-, 5-, or 10-year periods
        at the end of such periods, assuming reinvestment of all
        dividends and distributions.

Average Annual Total Return After Taxes on Distributions

The Funds' "average annual total return after taxes on distributions" figures are computed according to a formula prescribed by the Commission. The formula can be expressed as follows:

P(1+T)(n) = ATV(D)

Where:

P       =  a hypothetical initial payment of $1000.
T       =  average annual total return.
n       =  number of years.
ATV(D)  =  ending value of a hypothetical $1,000 payment made at
           the beginning of the 1-, 5-, or 10-year periods at the
           end of such periods, after taxes on fund distributions
           but not after taxes on redemption.

Average Annual Total Return After Taxes on Distributions and Redemptions

The Funds' "average annual total return after taxes on distributions and redemptions" figures are computed according to a formula prescribed by the SEC. The formula can be expressed as follows:

P(1+T)(n) = ATV(DR)

Where:

29

P        =  a hypothetical initial payment of $1000.
T        =  average annual total return.
n        =  number of years.
ATV(DR)  =  ending value of a hypothetical $1,000 payment made at
            the beginning of the 1-, 5-, or 10-year periods at
            the end of such periods, after taxes on fund
            distributions and redemption.

30-Day Yield

In addition to total return, the Funds may quote performance in terms of a 30-day yield. The yield figures provided will be calculated according to a formula prescribed by the SEC and can be expressed as follows:

          Yield =  2[({a-b/cd}+1)(6) - 1]

Where:

               a  =  dividends and interest earned during the period.
               b  =  expenses accrued for the period (net of
                     reimbursements).
               c  =  the average daily number of shares outstanding during
                     the period that were entitled to receive dividends.
               d  =  the maximum offering price per share on the last day
                     of the period.

For the purpose of determining the interest earned (variable "a" in the formula) on debt obligations that were purchased by a Fund at a discount or premium, the formula generally calls for amortization of the discount or premium; the amortization schedule will be adjusted monthly to reflect changes in the market value of the debt obligations.

Under this formula, interest earned on debt obligations for purposes of "a" above, is calculated by (1) computing the yield to maturity of each obligation held by a Fund based on the market value of the obligation (including actual accrued interest) at the close of business on the last day of each month, or, with respect to obligations purchased during the month, the purchase price (plus actual accrued interest), (2) dividing that figure by 360 and multiplying the quotient by the market value of the obligation (including actual accrued interest as referred to above) to determine the interest income on the obligation in a Fund's portfolio (assuming a month of 30 days) and (3) computing the total of the interest earned on all debt obligations during the 30-day or one month period. Undeclared earned income, computed in accordance with generally accepted accounting principles, may be subtracted from the maximum offering price calculation required pursuant to "d" above.

The Funds calculate their tax equivalent 30-day yield quotations by dividing that portion of the Fund's yield, as described above, that is tax-exempt by 1 minus a stated income tax rate and adding the quotient to that portion, if any, of the Fund's yield that is not tax-exempt.

The Funds' performance will vary from time to time depending on market conditions, the composition of its portfolio and operating expenses. Consequently, any given performance quotation should not be considered representative of the performance of a Fund for any specified period in the future. Because performance will vary, it may not provide a basis for comparing an investment in shares of a Fund with certain bank deposits or other investments that may pay a fixed return for a stated period of time. Investors comparing a Fund's performance with that of other mutual funds should give consideration to the nature, quality and maturity of the respective investment companies' portfolio securities and market conditions. An investor's principal is not guaranteed by the Funds.

FINANCIAL STATEMENTS

The audited financial statements for the fiscal year ended December 31, 2005 for (i) Equity 500 Index Fund and the State Street Equity 500 Index Portfolio; and (ii) Liquid Reserves Fund and State Street Money Market Portfolio, included in the Annual Report of the Trust, which was filed with the SEC on March 1, 2006, are incorporated into this SAI by reference. The Annual Report is available, without charge, upon request, by calling

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(877) 521-4083 or, if applicable, the customer service center at the telephone number shown in the accompanying Contract prospectus, if applicable, or by writing the Trust.

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APPENDIX A

RATINGS OF DEBT INSTRUMENTS

MOODY'S INVESTORS SERVICE, INC. ("MOODY'S") - LONG TERM DEBT RATINGS. The
following is a description of Moody's debt instrument ratings.

Aaa - Bonds that are rated Aaa are judged to be of the best quality. They carry the smallest degree of investment risk and are generally referred to as "gilt edged." Interest payments are protected by a large or exceptionally stable margin, and principal is secure. While the various protective elements are likely to change, such changes as can be visualized are most unlikely to impair the fundamentally strong position of such issues.

Aa - Bonds that are rated Aa are judged to be of high quality by all standards. Together with the Aaa group they comprise what are generally known as high-grade bonds. They are rated lower than the best bonds because margins of protection may not be as large as in Aaa securities, fluctuation of protective elements may be of greater amplitude, or there may be other elements present that make the long-term risk appear somewhat larger than that of the Aaa securities.

A - Bonds that are rated A possess many favorable investment attributes and are to be considered as upper-medium-grade obligations. Factors giving security to principal and interest are considered adequate, but elements may be present that suggest a susceptibility to impairment sometime in the future.

Moody's applies numerical modifiers 1, 2 and 3 in each generic rating classification from Aa through B. The modifier 1 indicates that the obligation ranks in the higher end of its generic rating category; the modifier 2 indicates a midrange ranking; and the modifier 3 indicates a ranking in the lower end of that generic rating category.

STANDARD & POOR'S RATING GROUP ("S&P"). S&P's ratings are based, in varying degrees, on the following considerations: (i) the likelihood of default - capacity and willingness of the obligor as to the timely payment of interest and repayment of principal in accordance with the terms of the obligation; (ii) the nature of and provisions of the obligation; and (iii) the protection afforded by, and relative position of, the obligation in the event of bankruptcy, reorganization, or other arrangement under the laws of bankruptcy and other laws affecting creditors' rights.

AAA - Debt rated AAA has the highest rating assigned by S&P. Capacity to pay interest and repay principal is extremely strong.

AA - Debt rated AA has a very strong capacity to pay interest and repay principal and differs from the highest rated issues only in small degree.

A - Debt rated A has a strong capacity to pay interest and repay principal, although it is somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than debt in higher rated categories.

Plus (+) or minus (-): The ratings from AA to CCC may be modified by the addition of a plus or minus sign to show relative standing within the major rating categories.

RATINGS OF COMMERCIAL PAPER

MOODY'S. Moody's short-term debt ratings are opinions of the ability of issuers to repay punctually senior debt obligations. These obligations have an original maturity not exceeding one year, unless explicitly noted. Moody's employs the following three designations, all judged to be investment grade, to indicate the relative repayment ability of rated issuers:

A-1

Issuers rated Prime-1 (or supporting institutions) have a superior ability for repayment of senior short-term debt obligations. Prime-1 repayment ability will often be evidenced by many of the following characteristics:

- Leading market positions in well-established industries.

- High rates of return on funds employed.

- Conservative capitalization structure with moderate reliance on debt and ample asset protection.

- Broad margins in earnings coverage of fixed financial charges and high internal cash generation.

- Well-established access to a range of financial markets and assured sources of alternate liquidity.

Issuers rated Prime-2 (or supporting institutions) have a strong ability for repayment of senior short-term debt obligations. This will normally be evidenced by many of the characteristics cited above but to a lesser degree. Earnings trends and coverage ratios, while sound, may be more subject to variation. Capitalization characteristics, while still appropriate, may be more affected by external conditions. Ample alternative liquidity is maintained.

Issuers rated Not Prime do not fall within any of the Prime rating categories.

S&P. An S&P commercial paper rating is a current assessment of the likelihood of timely payment of debt considered short-term in the relevant market. Ratings are graded into several categories, ranging from A-1 for the highest quality obligations to D for the lowest. These categories are as follows:

A-1 - This highest category indicates that the degree of safety regarding timely payment is strong. Those issues determined to possess extremely strong safety characteristics are deemed with a plus sign (+) designation.

A-2 - Capacity for timely payment on issues with this designation is satisfactory. However, the relative degree of safety is not as high as for issues designated A-1.

FITCH, INC. ("FITCH"). Commercial paper rated by Fitch reflects Fitch's current appraisal of the degree of assurance of timely payment of such debt. An appraisal results in the rating of an issuer's paper as F-1, F-2, F-3, or F-4.

F-1 - This designation indicates that the commercial paper is regarded as having the strongest degree of assurance for timely payment.

F-2 - Commercial paper issues assigned this rating reflect an assurance of timely payment only slightly less in degree than those issues rated F-1.

A-2

APPENDIX B

STATE STREET MASTER FUNDS
STATE STREET INSTITUTIONAL INVESTMENT TRUST

PROXY VOTING POLICY AND PROCEDURES

The Board of Trustees of State Street Master Funds and State Street Institutional Investment Trust (the "Trusts") has determined that it is in the best interests of the Trusts and their respective series (each, a "Fund" and collectively, the "Funds") for the Trusts to adopt the following policy and procedures with respect to voting proxies relating to portfolio securities held by certain of the Funds.

I. POLICY

It is the policy of the Trusts to delegate the responsibility for voting proxies relating to portfolio securities held by the Funds to SSgA Funds Management, Inc. (the "Adviser") as a part of the Adviser's general management of the Funds' portfolios, subject to the Board's continuing oversight. The Board of Trustees of the Trusts (the "Board") hereby delegates such responsibility to the Adviser, and directs the Adviser to vote proxies relating to portfolio securities held by each Fund consistent with the duties and procedures set forth below. The Adviser may retain one or more vendors to review, monitor and recommend how to vote proxies in a manner consistent with the duties and procedures set forth below, to ensure that such proxies are voted on a timely basis and to provide reporting and/or record retention services in connection with proxy voting for the Funds.

II. FIDUCIARY DUTY

The right to vote a proxy with respect to portfolio securities held by a Fund is an asset of such Fund. The Adviser, to which authority to vote on behalf of the Funds is delegated, acts as a fiduciary of the Funds and must vote proxies in a manner consistent with the best interest of the Funds and their shareholders. In discharging this fiduciary duty, the Adviser must maintain and adhere to its policies and procedures for addressing conflicts of interest and must vote proxies in a manner substantially consistent with its policies, procedures and guidelines, as presented to the Board.

III. PROCEDURES

The following are the procedures adopted by the Board for the administration of this policy:

A. Review of Adviser Proxy Voting Procedures. The Adviser shall present to the Board its policies, procedures and other guidelines for voting proxies at least annually, and must notify the Board promptly of material changes to any policies and procedures.

B. Voting Record Reporting. The Adviser shall provide the voting record information necessary for the completion and filing of Form N-PX to the Trusts at least annually. Such voting record information shall be in a form acceptable to the Trusts and shall be provided at such time(s) as are required for the timely filing of Form N-PX and at such additional time(s) as the Trusts and the Adviser may agree to from time to time. With respect to those proxies that the Adviser has identified as involving a conflict of interest(1), the Adviser shall submit a separate report indicating


(1) As it is used in this document, the term "conflict of interest" refers to a situation in which the principal underwriter, Adviser or affiliated persons of the principal underwriter or Adviser have an interest in a matter presented by a proxy other than the obligation it incurs as a service provider to the Funds which could potentially compromise the principal underwriter's or Adviser's independence of judgment and action with respect to the voting of the proxy.

B-1

the nature of the conflict of interest and how that conflict was resolved with respect to the voting of the proxy.

C. Record Retention. The Adviser shall maintain such records with respect to the voting of proxies as may be required by the Investment Advisers Act of 1940 and the rules promulgated thereunder or by the Investment Company Act of 1940, as amended and the rules promulgated thereunder.

D. Conflicts of Interest. Any actual or potential conflicts of interest between a Fund's principal underwriter or Adviser and the applicable Fund's shareholders arising from the proxy voting process will be addressed by the Adviser and the Adviser's application of its proxy voting procedures pursuant to the delegation of proxy voting responsibilities to the Adviser. In the event that the Adviser notifies the officer(s) of the Trusts that a conflict of interest cannot be resolved under the Adviser's Proxy Voting Procedures, such officer(s) are responsible for notifying the Audit Committee of the Trusts of the irreconcilable conflict of interest and assisting the Audit Committee with any actions it determines are necessary.

IV. REVOCATION

The delegation by the Board of the authority to vote proxies relating to portfolio securities of the Funds is entirely voluntary and may be revoked by the Board, in whole or in part, at any time.

V. ANNUAL FILING

The Trusts shall file an annual report of each proxy voted with respect to portfolio securities of the Funds during the twelve-month period ended June 30 on Form N-PX not later than August 31 of each year.(2)

VI. DISCLOSURES

A. The Trusts shall include in its registration statement:

1. A description of this policy and of the policies and procedures used by the Adviser to determine how to vote proxies relating to portfolio securities; and

2. A statement disclosing that information regarding how the Trusts voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is available without charge, upon request, by calling the Trusts' toll-free telephone number; or through a specified Internet address; or both; and on the Securities and Exchange Commission's (the "SEC") website.

B. The Trusts shall include in its annual and semi-annual reports to shareholders:

1. A statement disclosing that a description of the policies and procedures used by or on behalf of the Trusts to determine how to vote proxies relating to portfolio securities of the Funds is available without charge, upon request, by calling the Trusts' toll-free telephone number; through a specified Internet address, if applicable; and on the SEC's website; and

2. A statement disclosing that information regarding how the Trusts voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is available without charge, upon request, by calling the Trusts' toll-free telephone number; or through a specified Internet address; or both; and on the SEC's website.


(2) The Trusts must file their first report on Form N-PX not later than August 31, 2004, for the twelve-month period beginning July 1, 2003, and ending June 30, 2004.

B-2

VII. REVIEW OF POLICY.

The Board shall review this policy to determine its sufficiency and shall make and approve any changes that it deems necessary from time to time.

B-3

APPENDIX C

(SSGA LOGO)

PROXY VOTING POLICY Funds Management, Inc.

INTRODUCTION

SSgA Funds Management, Inc. ("FM") seeks to vote proxies in the best interests of its clients. In the ordinary course, this entails voting proxies in a way which FM believes will maximize the monetary value of each portfolio's holdings. FM takes the view that this will benefit our direct clients (e.g. investment funds) and, indirectly, the ultimate owners and beneficiaries of those clients (e.g. fund shareholders).

Oversight of the proxy voting process is the responsibility of the State Street Global Advisors (SSgA) Investment Committee. The SSgA Investment Committee reviews and approves amendments to the FM Proxy Voting Policy and delegates authority to vote in accordance with this policy to Proxy Voting Services. FM retains the final authority and responsibility for voting. In addition to voting proxies, FM:

1) describes its proxy voting procedures to its clients in Part II of its Form ADV;

2) provides the client with this written proxy policy, upon request;

3) discloses to its clients how they may obtain information on how FM voted the client's proxies;

4) matches proxies received with holdings as of record date;

5) reconciles holdings as of record date and rectifies any discrepancies;

6) generally applies its proxy voting policy consistently and keeps records of votes for each client;

7) documents the reason(s) for voting for all non-routine items; and

8) keeps records of such proxy voting available for inspection by the client or governmental agencies.

PROCESS

The SSgA FM Manager of Corporate Governance is responsible for monitoring proxy voting. As stated above, oversight of the proxy voting process is the responsibility of the SSgA Investment Committee, which retains oversight responsibility for all investment activities of all State Street Corporation investment firms.

In order to facilitate our proxy voting process, FM retains a firm with expertise in the proxy voting and corporate governance fields to assist in the due diligence process. The Manager of Corporate Governance is responsible, working with this firm, for ensuring that proxies are submitted in a timely manner.

All proxies received on behalf of FM clients are forwarded to our proxy voting firm. If (i) the request falls within one of the guidelines listed below, and
(ii) there are no special circumstances relating to that company or proxy which come to our attention (as discussed below), the proxy is voted according to our guidelines.

However, from time to time, proxy votes will be solicited which (i) involve special circumstances and require additional research and discussion or (ii) are not directly addressed by our policies. These proxies are identified through a number of methods, including but not limited to notification from our third party proxy voting specialist, concerns of clients, review by internal proxy specialists, and questions from consultants.

In instances of special circumstances or issues not directly addressed by our policies, the Chairman of the Investment Committee is consulted for a determination of the proxy vote. The first determination is whether there is a material conflict of interest between the interests of our client and those of FM. If the Manager of Corporate Governance and the Chairman of the Investment Committee determine that there is a material conflict, the process detailed below under "Potential Conflicts" is followed. If there is no material conflict, we examine each of the issuer's proposals in detail in seeking to determine what vote would be in the best interests of our clients. At this

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point, the Chairman of the Investment Committee makes a voting decision based on maximizing the monetary value of each portfolios' holdings. However, the Chairman of the Investment Committee may determine that a proxy involves the consideration of particularly significant issues and present the proxy to the entire Investment Committee for a decision on voting the proxy.

FM also endeavors to show sensitivity to local market practices when voting proxies of non-U.S. issuers. SSgA votes in all markets where it is feasible to do so. Note that certain custodians utilized by our clients do not offer proxy voting in every foreign jurisdiction. In such a case, FM will be unable to vote such a proxy.

VOTING

For most issues and in most circumstances, we abide by the following general guidelines. However, as discussed above, in certain circumstances, we may determine that it would be in the best interests of our clients to deviate from these guidelines.

Management Proposals

I. Generally, SSgA votes in support of management on the following ballot items, which are fairly common management sponsored initiatives.

- Elections of directors who do not appear to have been remiss in the performance of their oversight responsibilities and who do not simultaneously serve on an unreasonable (as determined by SSgA based on the particular facts and circumstances) number of other boards(other than those affiliated with the issuers)

- Approval of auditors

- Directors' and auditors' compensation

- Directors' liability and indemnification

- Discharge of board members and auditors

- Financial statements and allocation of income

- Dividend payouts that are greater than or equal to country and industry standards

- Authorization of share repurchase programs

- General updating of or corrective amendments to charter

- Change in Corporation Name

- Elimination of cumulative voting

II. Generally, SSgA votes in support of management on the following items, which have potentially substantial financial or best-interest impact:

- Capitalization changes which eliminate other classes of stock and voting rights

- Changes in capitalization authorization for stock splits, stock dividends, and other specified needs which are no more than 50% of the existing authorization for U.S. companies and no more than 100% of existing authorization for non-U.S. companies

- Elimination of pre-emptive rights for share issuance of less than a given percentage (country specific - ranging from 5% to 20%) of the outstanding shares

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- Elimination of "poison pill" rights

- Stock purchase plans with an exercise price of not less that 85% of fair market value

- Stock option plans which are incentive based and not excessive

- Other stock-based plans which are appropriately structured

- Reductions in super-majority vote requirements

- Adoption of anti-"greenmail" provisions

III. Generally, SSgA votes against management on the following items, which have potentially substantial financial or best interest impact:

- Capitalization changes that add "blank check" classes of stock or classes that dilute the voting interests of existing shareholders

- Changes in capitalization authorization where management does not offer an appropriate rationale or which are contrary to the best interest of existing shareholders

- Anti-takeover and related provisions that serve to prevent the majority of shareholders from exercising their rights or effectively deter appropriate tender offers and other offers

- Amendments to bylaws which would require super-majority shareholder votes to pass or repeal certain provisions

- Elimination of Shareholders' Right to Call Special Meetings

- Establishment of classified boards of directors

- Reincorporation in a state which has more stringent anti-takeover and related provisions

- Shareholder rights plans that allow the board of directors to block appropriate offers to shareholders or which trigger provisions preventing legitimate offers from proceeding

- Excessive compensation

- Change-in-control provisions in non-salary compensation plans, employment contracts, and severance agreements which benefit management and would be costly to shareholders if triggered

- Adjournment of Meeting to Solicit Additional Votes

- "Other business as properly comes before the meeting" proposals which extend "blank check" powers to those acting as proxy

- Proposals requesting re-election of insiders or affiliated directors who serve on audit, compensation, and nominating committees.

IV. SSgA evaluates Mergers and Acquisitions on a case-by-case basis. Consistent with our proxy policy, we support management in seeking to achieve their objectives for shareholders. However, in all cases, SSgA uses its discretion in order to maximize shareholder value. SSgA generally votes as follows:

- Against offers with potentially damaging consequences for minority shareholders because of illiquid stock, especially in some non-US markets

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- For offers that concur with index calculators treatment and our ability to meet our clients return objectives for passive funds

- Against offers when there are prospects for an enhanced bid or other bidders

- For proposals to restructure or liquidate closed end investment funds in which the secondary market price is substantially lower than the net asset value

Shareholder Proposals

Traditionally, shareholder proposals have been used to encourage management and other shareholders to address socio-political issues. SSgA believes that it is inappropriate to use client assets to attempt to affect such issues. Thus, we examine shareholder proposals primarily to determine their economic impact on shareholders.

I. Generally, SSgA votes in support of shareholders on the following ballot items, which are fairly common shareholder-sponsored initiatives:

- Requirements that auditors attend the annual meeting of shareholders

- The establishment of annual elections of the board of directors unless the board is composed by a majority of independent directors, the board's key committees (auditing, nominating and compensation) are composed of independent directors, and there are no other material governance issues or performance issues

- Mandates requiring a majority of independent directors on the Board of Directors and the audit, nominating, and compensation committees

- Mandates that amendments to bylaws or charters have shareholder approval

- Mandates that shareholder-rights plans be put to a vote or repealed

- Establishment of confidential voting

- Expansions to reporting of financial or compensation-related information, within reason

- Repeals of various anti-takeover related provisions

- Reduction or elimination of super-majority vote requirements

- Repeals or prohibitions of "greenmail" provisions

- "Opting-out" of business combination provisions

- Proposals requiring the disclosure of executive retirement benefits if the issuer does not have an independent compensation committee

- Disclosure of Auditor and Consulting relationships when the same or related entities are conducting both activities

- Establishment of selection committee responsible for the final approval of significant management consultant contract awards where existing firms are already acting in an auditing function

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- Mandates that Audit, Compensation and Nominating Committee members should all be independent directors

- Mandates giving the Audit Committee the sole responsibility for the selection and dismissal of the auditing firm and any subsequent result of audits are reported to the audit committee

II. SSgA votes against shareholders on the following initiatives, which are fairly common shareholder-sponsored initiatives:

- Limits to tenure of directors

- Requirements that candidates for directorships own large amounts of stock before being eligible to be elected

- Restoration of cumulative voting in the election of directors

- Requirements that the company provide costly, duplicative, or redundant reports; or reports of a non-business nature

- Restrictions related to social, political, or special interest issues which affect the ability of the company to do business or be competitive and which have significant financial or best-interest impact

- Proposals which require inappropriate endorsements or corporate actions

- Requiring the company to expense stock options unless already mandated by FASB (or similar body) under regulations that supply a common valuation model

- Proposal asking companies to adopt full tenure holding periods for their executives

- Proposals requiring the disclosure of executive retirement benefits if the issuer has an independent compensation committee

Shareholder Activism

We at FM agree entirely with the United States Department of Labor's position that "where proxy voting decisions may have an effect on the economic value of the plan's underlying investment, plan fiduciaries should make proxy voting decisions with a view to enhancing the value of the shares of stock" (IB 94-2). Our proxy voting policy and procedures are designed to ensure that our clients receive the best possible returns on their investments. We meet directly with corporation representatives and participate in conference calls and third-party inquiries in order to ensure our processes are as fully informed as possible.

Through our membership in the Council of Institutional Investors as well as our contact with corporate pension plans, public funds, and unions, we are also able to communicate extensively with other shareholders regarding events and issues relevant to individual corporations, general industry, and current shareholder concerns.

In addition, FM monitors "target" lists of underperforming companies prepared by various shareholder groups, including: California Public Employee Retirement System, The City of New York - Office of the Comptroller, International Brotherhood of Teamsters, and Council of Institutional Investors. Companies, so identified, receive an individual, systematic review by the Corporate Governance Subcommittee of SSgA's Investment Committee.

As an active shareholder, FM's role is to ensure that corporate policies serve the best interests of the corporation's investor-owners. Though we do not seek involvement in the day-to-day operations of an organization, we recognize the need for conscientious oversight of and input into management decisions that may affect a company's value. To that end, our monitoring of corporate management and industry events is substantially more detailed than that of the typical voter. We have demonstrated our willingness to vote against management-sponsored initiatives and to support shareholder proposals when appropriate. To date we have not filed proposals or initiated letter-writing or

C-5

other campaigns, but have used our active participation in the corporate governance process--especially the proxy voting process--as the most effective means by which to communicate our and our clients' legitimate shareholder concerns. Should an issue arise in conjunction with a specific corporation that cannot be satisfactorily resolved through these means, we shall consider other approaches.

Through the consistent, conscientious execution of our responsibilities as both fiduciary and shareholder, FM is able to promote the best interests of its fellow shareholders and its clients. The SSgA Funds Management, Inc. Proxy Voting Policy provides for this active, informed participation in the management of those corporations in which we hold shares.

POTENTIAL CONFLICTS

As discussed above under Process, from time to time, FM will review a proxy which presents a potential material conflict. For example, FM or its affiliates may provide services to a company whose management is soliciting proxies, or to another entity which is a proponent of a particular proxy proposal. Another example could arise when FM has business or other relationships with participants involved in proxy contests, such as a candidate for a corporate directorship.

As a fiduciary to its clients, FM takes these potential conflicts very seriously. While FM's only goal in addressing any such potential conflict is to ensure that proxy votes are cast in the clients' best interests and are not affected by FM's potential conflict, there are a number of courses FM may take. The final decision as to which course to follow shall be made by the Investment Committee.

When the matter falls clearly within one of the proposals enumerated above, casting a vote which simply follows FM's pre-determined policy would eliminate FM's discretion on the particular issue and hence avoid the conflict.

In other cases, where the matter presents a potential material conflict and is not clearly within one of the enumerated proposals, or is of such a nature that FM believes more active involvement is necessary, the Chairman of the Investment Committee shall present the proxy to the Investment Committee, who will follow one of two courses of action. First, FM may employ the services of a third party, wholly independent of FM, its affiliates and those parties involved in the proxy issue, to determine the appropriate vote.

Second, in certain situations the Investment Committee may determine that the employment of a third party is unfeasible, impractical or unnecessary. In such situations, the Investment Committee shall make a decision as to the voting of the proxy. The basis for the voting decision, including the basis for the determination that the decision is in the best interests of FM's clients, shall be formalized in writing as a part of the minutes to the Investment Committee. As stated above, which action is appropriate in any given scenario would be the decision of the Investment Committee in carrying out its duty to ensure that the proxies are voted in the clients', and not FM's, best interests.

RECORDKEEPING

In accordance with applicable law, FM shall retain the following documents for not less than five years from the end of the year in which the proxies were voted, the first two years in FM's office:

1) FM's Proxy Voting Policy and any additional procedures created pursuant to such Policy;

2) a copy of each proxy statement FM receives regarding securities held by its clients (note: this requirement may be satisfied by a third party who has agreed in writing to do so or by obtaining a copy of the proxy statement from the EDGAR database);

3) a record of each vote cast by FM (note: this requirement may be satisfied by a third party who has agreed in writing to do so);

4) a copy of any document created by FM that was material in making its voting decision or that memorializes the basis for such decision; and

5) a copy of each written request from a client, and response to the client, for information on how FM voted the client's proxies.

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DISCLOSURE OF CLIENT VOTING INFORMATION

Any client who wishes to receive information on how its proxies were voted should contact its FM client service officer.

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PART C

ITEM 23. EXHIBITS

(a)(1) Declaration of Trust was filed previously as Exhibit (a) to the Trust's Registration Statement and is incorporated by reference herein.

(2) Form of Amendment No. 1 to Agreement and Declaration of Trust was filed previously as Exhibit (a)(1) to Post-Effective Amendment No. 10 and is incorporated by reference herein.

(3) Form of Amendment No. 2 to Agreement and Declaration of Trust was filed previously as Exhibit (a)(3) to Post-Effective Amendment No. 15 and is incorporated by reference herein.

(4) Form of Amendment No. 3 to Agreement and Declaration of Trust was filed previously as Exhibit (a)(4) to Post-Effective Amendment No. 15 and is incorporated by reference herein.

(b) Second Amended and Restated By-laws of the Trust were filed previously as Exhibit (b) to Post-Effective Amendment No. 12 to the Trust's Registration Statement and are incorporated by reference herein.

(c) Not applicable.

(d)(1) Investment Advisory Agreement between SSgA Funds Management, Inc. and the Trust was filed previously as Exhibit (d)(2) to Post-Effective Amendment No. 9+ and is incorporated by reference herein.

(2) Form of Amendment to Investment Advisory Contract between SSgA Funds Management, Inc. and the Trust was filed previously as Exhibit (d)(3) to Post-Effective Amendment No. 10 and is incorporated by reference herein.

(3) Form of Fee Waiver and Expense Reimbursement Agreement between SSgA Funds Management, Inc. and the Trust with respect to the State Street Institutional Liquid Reserves Fund is filed herewith.

(4) Form of Voluntary Fee Waiver Letter from SSgA Funds Management, Inc. to the Trust with respect to the State Street Institutional Liquid Reserves Fund is filed herewith.

(e)(1) Distribution Agreement between ALPS Distributors, Inc. and the Trust is filed herewith.

(2) Form of Selling Dealer Agreement was filed previously as Exhibit (e)(4) to Post-Effective Amendment No. 13 and is incorporated by reference herein.

(f) Not applicable.

(g)(1) Amended and Restated Custodian Agreement between State Street Bank and Trust Company and the Trust was filed previously as Exhibit (g)(1) to Post-Effective Amendment No. 9+ and is incorporated by reference herein.

(h)(1) Transfer Agent and Services Agreement between State Street Bank and Trust Company and the Trust was filed previously as Exhibit (h)(1) to Post-Effective Amendment No. 9+ and is incorporated by reference herein.


(2) Administration Agreement between State Street Bank and Trust Company and the Trust was filed previously as Exhibit (h)(2) to Post-Effective Amendment No. 9+ and is incorporated by reference herein.

(3) Form of Transfer Agent and Services Agreements between ALPS Mutual Fund Services, Inc. and the Trust related to the State Street Institutional Liquid Reserves Fund was filed previously as Exhibit (h)(3) to Post-Effective Amendment No. 13 and is incorporated by reference herein.

(4) Form of Master-Feeder Participation Agreement between State Street Master Funds and the Trust with respect to the State Street Equity 500 Index Fund is filed herewith.

(5) Form of Master-Feeder Participation Agreement between State Street Master Funds and the Trust with respect to the State Street Institutional Liquid Reserves Fund is filed herewith.

(i)(1) Legal Opinion of Ropes & Gray LLP was filed previously as Exhibit (i) to Pre-effective Amendment No. 1 to the Trust's Registration Statement and is incorporated by reference herein.

(2) Legal Opinion of Ropes & Gray LLP regarding the State Street Money Market Fund was filed previously as Exhibit (i)(2) to Post-Effective Amendment No. 10 and is incorporated by reference herein.

(3) Legal Opinion of Ropes & Gray LLP regarding the Class R Shares of the State Street Equity 500 Index Fund was filed previously as Exhibit
(i)(3) to Post-Effective Amendment No. 15 and is incorporated by reference herein.

(j) Consent of Ernst & Young LLP is filed herewith.

(k) Not applicable.

(l) Not applicable.

(m) Rule 12b-1 Plan was filed previously as Exhibit (m) to Post-Effective Amendment No. 15 and is incorporated by reference herein.

(n) Rule 18f-3 Plan was filed previously as Exhibit (n) to Post-Effective Amendment No. 15 and is incorporated by reference herein.

(p)(1) Joint Code of Ethics with the State Street Master Funds was filed previously as Exhibit (p)(1) to Post-Effective Amendment No. 13 and is incorporated by reference herein.

(2) Amended Code of Ethics of SSgA Funds Management, Inc. is filed herewith.

(3) Amended Code of Ethics of ALPS Distributors, Inc. is filed herewith.

+ Post-Effective Amendment No. 8 was filed with the Commission on January 30, 2002. The next Post-Effective Amendment, filed on April 30, 2002, should have been sequentially numbered Post-Effective Amendment No. 9. Due to a scrivener's error, it was numbered Post-Effective Amendment No. 10. Such Post-Effective Amendment has been referred to in this Part C as Post-Effective Amendment No. 9.

ITEM 24. PERSONS CONTROLLED BY OR UNDER COMMON CONTROL WITH THE FUND

See the Prospectus and the Statement of Additional Information regarding the Trust's control relationships.


ITEM 25. INDEMNIFICATION

Pursuant to Article 4 of the Trust's Amended and Restated By-Laws, the Trust shall indemnify each of its Trustees and officers (including persons who serve at the Trust's request as directors, officers or trustees of another organization in which the Trust has any interest as a shareholder, creditor or otherwise) (hereinafter referred to as a "Covered Person") against all liabilities and expenses, including but not limited to amounts paid in satisfaction of judgments, in compromise or as fines and penalties, and counsel fees reasonably incurred by any Covered Person in connection with the defense or disposition of any action, suit or other proceeding, whether civil or criminal, before any court or administrative or legislative body, in which such Covered Person may be or may have been involved as a party or otherwise or with which such Covered Person may be or may have been threatened, while in office or thereafter, by reason of any alleged act or omission as a Trustee or officer or by reason of his or her being or having been such a Trustee or officer, except with respect to any matter as to which such Covered Person shall have been finally adjudicated in any such action, suit or other proceeding not to have acted in good faith in the reasonable belief that such Covered Person's action was in the best interest of the Trust and except that no Covered Person shall be indemnified against any liability to the Trust or its Shareholders to which such Covered Person would otherwise be subject by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of such Covered Person's office. Expenses, including counsel fees so incurred by any such Covered Person, may be paid from time to time by the Trust in advance of the final disposition of any such action, suit or proceeding on the condition that the amounts so paid shall be repaid to the Trust if it is ultimately determined that indemnification of such expenses is not authorized under this Article.

As to any matter disposed of by a compromise payment by any such Covered Person referred to above, pursuant to a consent decree or otherwise, no such indemnification either for said payment or for any other expenses shall be provided unless such compromise shall be approved as in the best interests of the Trust, after notice that it involved such indemnification, (a) by a disinterested majority of the Trustees then in office; or (b) by a majority of the disinterested Trustees then in office; or (c) by any disinterested person or persons to whom the question may be referred by the Trustees, provided that in the case of approval pursuant to clause (b) or (c) there has been obtained an opinion in writing of independent legal counsel to the effect that such Covered Person appears to have acted in good faith in the reasonable belief that his or her action was in the best interests of the Trust and that such indemnification would not protect such person against any liability to the Trust or its Shareholders to which such person would otherwise be subject by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of office; or (d) by vote of Shareholders holding a majority of the Shares entitled to vote thereon, exclusive of any Shares beneficially owned by any interested Covered Person. Approval by the Trustees pursuant to clause (a) or (b) or by any disinterested person or persons pursuant to clause (c) of this Section shall not prevent the recovery from any Covered Person of any amount paid to such Covered Person in accordance with any of such clauses as indemnification if such Covered Person is subsequently adjudicated by a court of competent jurisdiction not to have acted in good faith in the reasonable belief that such Covered Person's action was in the best interests of the Trust or to have been liable to the Trust or its Shareholders by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of such Covered Person's office.

The right of indemnification hereby provided shall not be exclusive of or affect any other rights to which any such Covered Person may be entitled. As used in this Article 4, the term "Covered Person" shall include such person's heirs, executors and administrators; an "interested Covered Person" is one against whom the action, suit or other proceeding in question or another action, suit or other proceeding on the same or similar grounds is then or has been pending; and a "disinterested Trustee" or "disinterested person" is a Trustee or a person against whom none of such actions, suits or other proceedings or another action, suit or other proceeding on the same or similar grounds is then or has been pending. Nothing contained in this Article shall affect any rights to indemnification to which personnel of the Trust, other than Trustees and officers, and other persons may be entitled by contract or otherwise under law, nor the power of the Trust to purchase and maintain liability insurance on behalf of any such person.


ITEM 26. BUSINESS AND OTHER CONNECTIONS OF THE INVESTMENT ADVISER

See "Management of the Trust" in Part B. Information as to the directors and officers of the Adviser is included in its Form ADV filed with the SEC and is incorporated herein by reference thereto.

ITEM 27. PRINCIPAL UNDERWRITER

(a) The sole principal underwriter for the Trust is ALPS Distributors, Inc. which acts as distributor for the Trust and the following other investment companies: Accessor Funds, AARP Funds, Agile Funds, Ameristock Mutual Funds, Inc., BLDRS Index Fund Trust, Campbell Multi-Strategy Trust, CornerCap Group of Funds, DIAMONDS Trust, Drake Funds, Financial Investors Trust, Financial Investors Variable Insurance Trust, First Funds, Firsthand Funds, Forward Funds, Henssler Funds, Inc., Holland Balanced Fund, Laudus Trust, Milestone, Nasdaq 100 Trust, PowerShares Exchange-Traded Funds Trust, SPDR Trust, MidCap SPDR Trust, Select Sector SPDR Trust, Stonebridge Funds, Inc., Utopia Funds, W. P. Stewart Funds, Wasatch Funds, Westcore Trust, and Williams Capital Liquid Assets Fund.

(b) To the best of the Trust's knowledge, the directors and executive officers of ALPS Distributors, Inc., are as follows:

Edmund J. Burke   President

Thomas Carter     Managing Director - Sales and Finance;
                  Treasurer

Jeremy O. May     Managing Director - Operations and Client
                  Service; Secretary

Diana Adams       Vice President, Controller

Tane Tyler        Chief Legal Officer, Assistant Secretary

Brad Swenson      Chief Compliance Officer

* The principal business address for each of the above directors and executive officers is 1625 Broadway, Suite 2200, Denver, Colorado 80202.

ITEM 28. LOCATION OF ACCOUNTS AND RECORDS

The accounts and records of the Trust are located, in whole or in part, at the office of the Trust and the following locations:

State Street Institutional Investment Trust ("Trust") PO Box 5049 Boston, MA 02206

SSgA Funds Management, Inc. ("Adviser") State Street Financial Center
One Lincoln Street
Boston, MA 02111

State Street Bank and Trust Company ("Custodian, Administrator, Transfer Agent and Dividend Disbursing Agent", except not the Transfer Agent/Dividend Disbursing Agent for the State Street Institutional Liquid Reserves Fund)
2 Avenue de Lafayette
Boston, MA 02111


ALPS Distributors, Inc.
ALPS Mutual Fund Services, Inc. (Transfer Agent/Dividend Disbursing Agent for the State Street Institutional Liquid Reserves Fund) 1625 Broadway
Suite 2200
Denver, CO 80202

ITEM 29. MANAGEMENT SERVICES

Not applicable.

ITEM 30. UNDERTAKINGS

Not applicable.


SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 (the "1933 Act") and the Investment Company Act of 1940, the Registrant, State Street Institutional Investment Trust (the "Trust") certifies that it meets all of the requirements for effectiveness of this amendment to the Trust's registration statement under Rule 485(b) under the 1933 Act and has duly caused this Amendment to the Trust's Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Boston and Commonwealth of Massachusetts on the 28th day of April 2006.

STATE STREET INSTITUTIONAL INVESTMENT TRUST

By: /s/ James E. Ross
    ---------------------------------------
    James E. Ross
    President

Pursuant to the requirements of the 1933 Act, this Registration Statement for the Trust has been signed below by the following persons in the capacities indicated on the 28th day of April 2006:

Signature                     Title
---------                     -----


/s/ James E. Ross
---------------------------
James E. Ross                 President (Principal Executive Officer)


/s/ Gary L. French
---------------------------
Gary L. French                Treasurer (Principal Accounting Officer)


             *                Trustee
---------------------------
William L. Boyan


             *                Trustee
---------------------------
Michael F. Holland


             *                Trustee
---------------------------
Rina K. Spence


             *                Trustee
---------------------------
Douglas T. Williams

*    Attorney-in-fact: /s/ Ryan M. Louvar
                       -------------------------
(pursuant to Powers of Attorney filed herewith)


STATE STREET INSTITUTIONAL INVESTMENT TRUST

INDEX TO EXHIBITS

Exhibit
Number    Description of Exhibit
-------   ----------------------
(d)(3)    Form of Fee Waiver and Expense Reimbursement Agreement between SSgA
          Funds Management, Inc. and the Trust with respect to the State Street
          Institutional Liquid Reserves Fund

(d)(4)    Form of Voluntary Fee Waiver Letter from SSgA Funds Management, Inc.
          to the Trust with respect to the State Street Institutional Liquid
          Reserves Fund

(e)(1)    Distribution Agreement between ALPS Distributors, Inc. and the Trust

(h)(4)    Form of Master-Feeder Participation Agreement between State Street
          Master Funds and the Trust with respect to the State Street Equity 500
          Index Fund.

(h)(5)    Form of Master-Feeder Participation Agreement between State Street
          Master Funds and the Trust with respect to the State Street
          Institutional Liquid Reserves Fund is filed herewith.

(j)       Consent of Ernst & Young LLP

(p)(2)    Amended Code of Ethics of SSgA Funds Management, Inc.

(p)(3)    Amended Code of Ethics of ALPS Distributors, Inc.


POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that the undersigned, a Trustee of State Street Institutional Investment Trust, constitutes and appoints each of Ryan M. Louvar, Julie A. Tedesco and Tim P. Walsh, as his true and lawful attorney-in-fact and agent, each with full power of substitution and resubstitution for such attorney-in-fact in such attorney-in-fact's name, place and stead, to sign any and all Post-Effective Amendments and/or Amendments to the Registration Statement of State Street Institutional Investment Trust on Form N-1A (Securities Act File No. 333-30810 and Investment Company Act File No. 811-9819) and any filings made with any state regulatory agency or authority, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission or any state regulatory agency or authority, as appropriate, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Any one of such attorneys and agents has, and may exercise, all of the powers hereby conferred. The undersigned hereby revokes any Powers of Attorney previously granted with respect to State Street Institutional Investment Trust concerning the filings and actions described herein.

IN WITNESS WHEREOF, the undersigned has hereunto set his hand as of the 15th day of April, 2006.

               SIGNATURE                 TITLE
               ---------                -------


/s/ William L. Boyan                    Trustee
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William L. Boyan


POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that the undersigned, a Trustee of State Street Institutional Investment Trust, constitutes and appoints each of Ryan M. Louvar, Julie A. Tedesco and Tim P. Walsh, as his true and lawful attorney-in-fact and agent, each with full power of substitution and resubstitution for such attorney-in-fact in such attorney-in-fact's name, place and stead, to sign any and all Post-Effective Amendments and/or Amendments to the Registration Statement of State Street Institutional Investment Trust on Form N-1A (Securities Act File No. 333-30810 and Investment Company Act File No. 811-9819) and any filings made with any state regulatory agency or authority, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission or any state regulatory agency or authority, as appropriate, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Any one of such attorneys and agents has, and may exercise, all of the powers hereby conferred. The undersigned hereby revokes any Powers of Attorney previously granted with respect to State Street Institutional Investment Trust concerning the filings and actions described herein.

IN WITNESS WHEREOF, the undersigned has hereunto set his hand as of the 15th day of April, 2006.

                SIGNATURE                TITLE
                ---------               -------


/s/ Michael F. Holland                  Trustee
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Michael F. Holland


POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that the undersigned, a Trustee of State Street Institutional Investment Trust, constitutes and appoints each of Ryan M. Louvar, Julie A. Tedesco and Tim P. Walsh, as her true and lawful attorney-in-fact and agent, each with full power of substitution and resubstitution for such attorney-in-fact in such attorney-in-fact's name, place and stead, to sign any and all Post-Effective Amendments and/or Amendments to the Registration Statement of State Street Institutional Investment Trust on Form N-1A (Securities Act File No. 333-30810 and Investment Company Act File No. 811-9819) and any filings made with any state regulatory agency or authority, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission or any state regulatory agency or authority, as appropriate, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Any one of such attorneys and agents has, and may exercise, all of the powers hereby conferred. The undersigned hereby revokes any Powers of Attorney previously granted with respect to State Street Institutional Investment Trust concerning the filings and actions described herein.

IN WITNESS WHEREOF, the undersigned has hereunto set her hand as of the 15th day of April, 2006.

                SIGNATURE                TITLE
                ---------               -------


/s/ Rina K. Spence                      Trustee
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Rina K. Spence


POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that the undersigned, a Trustee of State Street Institutional Investment Trust, constitutes and appoints each of Ryan M. Louvar, Julie A. Tedesco and Tim P. Walsh, as his true and lawful attorney-in-fact and agent, each with full power of substitution and resubstitution for such attorney-in-fact in such attorney-in-fact's name, place and stead, to sign any and all Post-Effective Amendments and/or Amendments to the Registration Statement of State Street Institutional Investment Trust on Form N-1A (Securities Act File No. 333-30810 and Investment Company Act File No. 811-9819) and any filings made with any state regulatory agency or authority, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission or any state regulatory agency or authority, as appropriate, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Any one of such attorneys and agents has, and may exercise, all of the powers hereby conferred. The undersigned hereby revokes any Powers of Attorney previously granted with respect to State Street Institutional Investment Trust concerning the filings and actions described herein.

IN WITNESS WHEREOF, the undersigned has hereunto set his hand as of the 15th day of April, 2006.

       SIGNATURE           TITLE
       ---------          -------


/s/ Douglas T. Williams   Trustee
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Douglas T. Williams


EXHIBIT (D)(3)

FORM OF FEE WAIVER AND EXPENSE REIMBURSEMENT AGREEMENT

AGREEMENT, made as of this 1st day of April, 2006, between State Street Institutional Investment Trust (the "Trust") on behalf of its State Street Institutional Liquid Reserves Fund series (the "Fund"), and SSgA Funds Management, Inc. ("SSgA FM").

WHEREAS, the Fund currently invests all of its investable assets in the State Street Money Market Portfolio, a series of State Street Master Funds (the "Master Portfolio");

WHEREAS, the parties have entered into an Investment Advisory Agreement with respect to the Fund ("Advisory Agreement"); and

WHEREAS, no investment advisory fee is payable to SSgA FM under the Advisory Agreement at any time the Fund is invested in a master-feeder structure; and

WHEREAS, SSgA FM desires to reduce the investment advisory fee charged to the Fund described in the Advisory Agreement (in the event the Fund no longer invests in a master-feeder structure and Fund assets are directly managed by SSgA FM) and/or reimburse certain operating expenses for the Fund to keep expenses at specified levels as set forth below.

NOW, THEREFORE, in consideration of the premises and mutual covenants herein contained, the Trust and SSgA FM agree as follows:

1. For the period commencing as of the date of this Agreement through November 1, 2007, SSgA FM agrees to waive fees payable to SSgA FM pursuant to the Advisory Agreement (in the event the Fund no longer invests in a master-feeder structure and Fund assets are directly managed by SSgA FM) and/or reimburse operating expenses for the Fund in an amount sufficient to keep the total annual operating expenses (exclusive of interest, taxes, extraordinary expenses and the pass-thru expenses from the Master Portfolio) for the Fund at 0.05%.

2. SSgA FM understands and intends that the Fund will rely on this agreement in preparing and filing its registration statement on Form N-1A (including any amendments or supplements thereto) and in accruing the expenses of the Fund for purposes of calculating net asset value and otherwise, and expressly permits the Fund to do so.

IN WITNESS WHEREOF, the parties hereto have caused this instrument to be executed by their officers designated below as of the day and year first written above.

STATE STREET INSTITUTIONAL INVESTMENT   SSGA FUNDS MANAGEMENT, INC.
TRUST


By:                                     By:
    ---------------------------------       ------------------------------------
Name: Gary L. French                    Name: James E. Ross
Title: Treasurer                        Title: President


EXHIBIT (D)(4)

SSGA FUNDS MANAGEMENT, INC.
STATE STREET FINANCIAL CENTER
ONE LINCOLN STREET
BOSTON, MA 02111-2900

April 1, 2006

Ryan M. Louvar
Assistant Secretary
State Street Institutional Investment Trust c/o State Street Bank and Trust Company
P.O. Box 5049
Boston, MA 02206-5049
Fax: 617-662-3805

Re: VOLUNTARY EXPENSE LIMITATION -
STATE STREET INSTITUTIONAL LIQUID RESERVES FUND (THE "FUND")

Dear Ryan:

I am sending you this letter to confirm that SSgA Funds Management, Inc. ("SSgA FM"), the investment adviser to the Fund, a fund that invests substantially all of its investment assets in the State Street Money Market Portfolio (the "Master Portfolio"), has voluntarily agreed to continue to cap the total operating expenses of the Fund (not including the pass-through expenses of the Master Portfolio) at 0.02% of the Fund's average daily net assets ("Voluntary Expense Limitation"). This Voluntary Expense Limitation was originally effective August 1, 2005 and is in addition to the current contractual cap of 0.05% of the Fund's average daily net assets; however, this Voluntary Expense Limitation may be revised or canceled at any time upon written notice to the Fund.

SSgA FM understands and intends that the Fund will rely on this letter agreement in preparing and filing its registration statement on Form N-1A (including any amendments or supplements thereto) and in accruing the expenses of the Fund for purposes of calculating net asset value and otherwise, and expressly permits the Fund to do so.

Please do not hesitate to contact me with any questions at 617-664-2043.

Very truly yours,


James E. Ross President

EXHIBIT (E)(1)

DISTRIBUTION AGREEMENT

Distribution Agreement made this 30th day of September, 2005, by and between The State Street Institutional Investment Trust, a Massachusetts trust (the "Trust"), and ALPS Distributors, Inc., a Colorado corporation (the "Distributor").

WHEREAS, the Trust is a registered open-end management investment company organized as a series trust offering a number of portfolios of securities (each a "Fund" and collectively the "Funds"), each investing primarily in interests of a portfolio of the State Street Master Trust, having filed with the Securities and Exchange Commission (the "Commission") a registration statement on Form N-1A under the Securities Act of 1933, as amended (the "1933 Act"), and the Investment Company Act of 1940, as amended;

WHEREAS, the Trust desires to retain the services of the Distributor in connection with the promotion and distribution of the shares of each Fund (the "Shares");

WHEREAS, the Board of Trustees of the Trust has adopted a plan of distribution (the "12b-1 Plan") pursuant to Rule 12b-1 under the 1940 Act with respect to each Fund and may make payments to the Distributor pursuant to such 12b-1 Plan, subject to and in accordance with the terms and conditions thereof and any related agreements;

WHEREAS, the Distributor is a registered broker-dealer under the Securities Exchange Act of 1934, as amended (the "1934 Act") and a member of the National Association of Securities Dealers ("NASD"); and

WHEREAS, the Distributor desires to provide such services to the Trust.

NOW, THEREFORE, in consideration of the mutual promises and undertakings herein contained, the parties agree as follows:

1. Appointment. The Trust hereby appoints the Distributor as the exclusive distributor for Shares of each Fund listed in Annex I hereto, as the same may be amended by the parties from time to time, on the terms and for the period set forth in this Agreement and subject to the registration requirements of the 1933 Act and of the laws governing the sale of securities in the various states, and the Distributor hereby accepts such appointment and agrees to act in such capacity hereunder.

2. Definitions. Wherever they are used herein, the following terms have the following respective meanings:

a. "1940 Act" means the Investment Company Act of 1940 and the rules and regulations thereunder as amended from time to time;

b. "Prospectus" means the Prospectus and Statement of Additional Information constituting parts of the Registration Statement of the Trust under the 1933 Act and the 1940 Act as such Prospectus and Statement of Additional Information may be amended or supplemented and filed with the Commission from time to time;


c. "Registration Statement" means the registration statement most recently filed from time to time by the Trust with the Commission and effective under the 1933 Act and the 1940 Act, as such registration statement is amended by any amendments thereto at the time in effect;

d. All capitalized terms used but not defined in this Agreement shall have the meanings ascribed to such terms in the Registration Statement and the Prospectus.

3. Duties of the Distributor.

(a) The Trust grants to the Distributor the right to sell the Shares as agent on behalf of each Fund, during the term of this Agreement, subject to the registration requirements of the 1933 Act and the 1940 Act and of the laws governing the sale of securities in the various states ("Blue Sky Laws"), under the terms and conditions set forth in this Agreement. The Distributor shall have the right to sell, as agent on behalf of each Fund, the Shares covered by the registration statement, prospectus and statement of additional information for the Trust then in effect under the 1933 Act and the 1940 Act.

(b) The Distributor agrees to act as agent of the Trust with respect to the continuous distribution of Shares of each Fund as set forth in the Registration Statement and in accordance with the provisions thereof. The Distributor further agrees as follows: (a) the Distributor shall generate and transmit confirmations of Share purchase order acceptances to the purchaser; (b) the Distributor shall deliver copies of the prospectus, included in the Registration Statement, to purchasers of such Shares and upon request the Statement of Additional Information; and (c) the Distributor shall maintain telephonic, facsimile and/or access to direct computer communications links with the Transfer Agent.

(c) The rights granted to the Distributor shall be nonexclusive in that the Trust reserves the right to sell Shares to investors on applications received and accepted by the Trust.

(d) The Distributor agrees to administer the Rule 12b-1 Plan on behalf of the Trust. The Distributor shall, at its own expense, set up and maintain a system of recording and payments for fees and reimbursement of expenses disseminated pursuant to this Agreement and any other related agreements under the Funds' Rule 12b-1 Plan and shall, pursuant to the 1940 Act, report such payment activity under the Rule 12b-1 Plan to the Trust at least quarterly.

(e) All activities by the Distributor and its agents and employees which are primarily intended to result in the sale of Shares shall comply with the Registration Statement and Prospectus, the instructions of the Board of Trustees of the Trust and all applicable laws, rules and regulations including, without limitation, all rules and regulations made or adopted pursuant to the 1940 Act by the Commission or any securities association registered under the 1934 Act, including the NASD.

(f) Except as otherwise noted in the Registration Statement and Prospectus, the offering price for all Shares will be the aggregate net asset value of the Shares of the relevant Fund, as determined in the manner described in the Registration Statement and Prospectus.

(g) If and whenever the determination of net asset value is suspended and until such suspension is terminated, no further orders for Shares will be processed by the Distributor except such unconditional orders as may have been placed with the Distributor before it had knowledge of the suspension. In addition, the Trust reserves the right to suspend sales and Distributor's authority to process orders for Shares on behalf of the Trust, upon due notice to the Distributor, if, in the judgment of the Trust, it is in the best interests of the Trust to do so. Suspension will continue for such period as may be determined by the Trust.

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(h) The Distributor is not authorized by the Trust to give any information or to make any representations other than those contained in the Registration Statement or Prospectus or contained in shareholder reports or other material that may be prepared by or on behalf of the Trust for the Distributor's use. The Distributor shall be entitled to rely on and shall not be responsible in any way for information provided to it by the Trust and its respective service providers and shall not be liable or responsible for the errors and omissions of such service providers, provided that the foregoing shall not be construed to protect the Distributor against any liability to the Trust or the Trust's shareholders to which the Distributor would otherwise be subject by reason of willful misfeasance, bad faith or gross negligence in the performance of its duties or by reason of its reckless disregard of its obligations and duties under this Agreement.

(i) The Board of Trustees shall approve the form of any Investor Services Agreement to be entered into by the Distributor.

(j) At the request of the Trust, the Distributor shall enter into agreements in the form specified by the Trust (each a "Participant Agreement") with participants in the system for book-entry of The Depository Trust Company and the NSCC as described in the Prospectus.

(k) The Distributor shall ensure that all direct requests for Prospectuses and Statements of Additional of Information are fulfilled. The Distributor will generally make it known in the brokerage community that prospectuses and statements of additional information are available, including by (i) making such disclosure in all marketing and advertising materials prepared and/or filed by the Distributor with the NASD, and (ii) as may otherwise be required by the Commission.

(l) The Distributor agrees to make available, at the Trust's request, one or more members of its staff to attend Board meetings of the Trust in order to provide information with regard to the ongoing distribution process and for such other purposes as may be requested by the Board of Trustees of the Trust.

4. Duties of the Trust.

(a) The Trust agrees to issue Shares of each Fund and to request The Depository Trust Company to record on its books the ownership of such Shares in accordance with the book-entry system procedures described in the Prospectus in such amounts as the Distributor has requested through the Transfer Agent in writing or by other means of data transmission, as promptly as practicable after receipt by the Trust of the requisite purchase price and acceptance of such order, upon the terms described in the Registration Statement. The Trust may reject any order for Shares or stop all receipts of such orders at any time upon reasonable notice to the Distributor, in accordance with the provisions of the Prospectus.

(b) The Trust agrees that it will take all action necessary to register an indefinite number of Shares under the 1933 Act. The Trust will make available to the Distributor such number of copies of its then currently effective Prospectus as the Distributor may reasonably request. The Trust will furnish to the Distributor copies of all information, financial statements and other papers that the Distributor may reasonably request for use in connection with the distribution of Shares. The Trust shall keep the Distributor informed of the jurisdictions in which Shares of the Trust are authorized for sale and shall promptly notify the Distributor of any change in this information. The Distributor shall not be liable for damages resulting from the sale of Shares in authorized jurisdictions where the Distributor had no information from the Trust that such sale or sales were unauthorized at the time of such sale or sales.

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(c) The Trust represents to the Distributor that the Registration Statement and Prospectus filed by the Trust with the Commission with respect to the Trust have been prepared in conformity with the requirements of the 1933 Act, the 1940 Act and the rules and regulations of the Commission thereunder. The Trust will notify the Distributor promptly of any amendment to the Registration Statement or supplement to the Prospectus and any stop order suspending the effectiveness of the Registration Statement.

5. Fees and Expenses.

(a) The Trust will, with respect to each Fund, pay to the Distributor all fees and expenses pursuant to the terms of the Rule 12b-1 Plan in effect for each respective Fund.

(b) The Distributor will bear the following costs and expenses relating to the distribution of Shares of the Funds: (a) the costs of maintaining the records required of a broker-dealer registered under the 1934 Act; (b) the expenses of maintaining its registration or qualification as a dealer or broker under federal or state laws; (c) the expenses incurred by the Distributor in connection with normal (non-expedited) NASD filing fees; and (d) all other expenses incurred in connection with the distribution services contemplated herein, except as specifically provided in this Agreement.

(c) The Distributor shall pay, from the fees received by it from the Funds pursuant to the Rule 12b-1 Plan, all fees and make reimbursement of expenses, pursuant to and in accordance with any and all Investor Services Agreements, as approved by the Board of Trustees of the Trust, as set forth in Section 3 of this Agreement. Further, the Distributor will pay, from the fees received by it from the Funds pursuant to the Rule 12b-1 Plan, all fees with respect to expedited NASD filing fees.

6. Indemnification.

(a) The Trust agrees to indemnify and hold harmless the Distributor and each of the directors, officers, agents and employees and any person who controls the Distributor within the meaning of Section 15 of the 1933 Act (any of the Distributor, its officers, agents, employees and directors or such control persons, for purposes of this paragraph, an "Indemnitee") against any loss, liability, claim, damages or expense (including the reasonable cost of investigating or defending any alleged loss, liability, claim, damages or expense and reasonable counsel fees incurred in connection therewith) arising out of or based upon the claim that the Registration Statement, Prospectus, shareholder reports or other information filed or made public by the Trust (as from time to time amended) included an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary in order to make the statements therein (and in the case of the Prospectus, in light of the circumstances under which they were made) not misleading under the 1933 Act, or any other statute or the common law. However, the Trust does not agree to indemnify the Distributor or hold it harmless to the extent that the statement or omission was made in reliance upon, and in conformity with information furnished to the Trust by or on behalf of the Distributor. The Trust will also not indemnify any Indemnitee with respect to any untrue statement or omission made in the Registration Statement or Prospectus that is subsequently corrected in such document (or an amendment thereof or supplement thereto) if a copy of the Prospectus (or such amendment or supplement) was not sent or given to the person asserting any such loss, liability, claim, damage or expense at or before the written confirmation to such person in any case where such delivery is required by the 1933 Act and the Trust had notified the Distributor of the amendment or supplement prior to the sending of the confirmation. In no case (i) is the indemnity of the Trust in favor of any Indemnitee to be deemed to protect the Indemnitee against any liability to the Trust or its shareholders to which the Indemnitee would otherwise be subject by reason of willful misfeasance, bad faith or gross negligence in the performance of its duties or by reason of its reckless disregard of its obligations and duties under this Agreement, or (ii) is

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the Trust to be liable under its indemnity agreement contained in this paragraph with respect to any claim made against any Indemnitee unless the Indemnitee shall have notified the Trust in writing of the claim within a reasonable time after the summons or other first written notification giving information of the nature of the claim shall have been served upon Indemnitee (or after Indemnitee shall have received notice of service on any designated agent). However, failure to notify the Trust of any claim shall not relieve the Trust from any liability which it may have to any Indemnitee against whom such action is brought otherwise than on account of its indemnity agreement contained in this paragraph. The Trust shall be entitled to participate at its own expense in the defense, or, if it so elects, to assume the defense of any suit brought to enforce any claims, but if the Trust elects to assume the defense, the defense shall be conducted by counsel chosen by it and satisfactory to Indemnitee, defendant or defendants in the suit. In the event the Trust elects to assume the defense of any suit and retain counsel, Indemnitee, defendant or defendants in the suit, shall bear the fees and expenses of any additional counsel retained by them. If the Trust does not elect to assume the defense of any suit, it will reimburse the Indemnitee, defendant or defendants in the suit, for the reasonable fees and expenses of any counsel retained by them. The Trust agrees to notify the Distributor and any Indemnified Dealer promptly of the commencement of any litigation or proceedings against it or any of its officers or trustees in connection with the issuance or sale of any of the Shares.

(b) The Distributor agrees to indemnify and hold harmless the Trust and each of its Trustees and officers and any person who controls the Trust within the meaning of Section 15 of the 1933 Act (for purposes of this paragraph, the Trust and each of its Trustees and officers and its controlling persons are collectively referred to as the "Trust Affiliates") against any loss, liability, claim, damages or expense (including the reasonable cost of investigating or defending any alleged loss, liability, claim, damages or expense and reasonable counsel fees incurred in connection therewith) which the Trust Affiliate may incur under the 1933 Act or any other statute or common law, but only to the extent that such loss, liability, claim, damages or expense shall arise out of or be based upon (i) the allegation of any wrongful act of the Distributor or any of its employees or (ii) allegation that the Registration Statement, Prospectus, shareholder reports or other information filed or made public by the Trust (as from time to time amended) included an untrue statement of a material fact or omitted to state a material fact required to be stated or necessary in order to make the statements not misleading, insofar as the statement or omission was made in reliance upon, and in conformity with information furnished to the Trust by or on behalf of the Distributor. In no case (i) is the indemnity of the Distributor in favor of any Trust Affiliate to be deemed to protect any Trust Affiliate against any liability to the Trust or its security holders to which such Trust Affiliate would otherwise be subject by reason of willful misfeasance, bad faith or gross negligence in the performance of its duties or by reason of its reckless disregard of its obligations and duties under this Agreement, or (ii) is the Distributor to be liable under its indemnity agreement contained in this paragraph with respect to any claim made against any Trust Affiliate unless the Trust Affiliate shall have notified the Distributor in writing of the claim within a reasonable time after the summons or the first written notification giving information of the nature of the claim shall have been served upon the Trust Affiliate (or after the Trust Affiliate shall have received notice of service on any designated agent). However, failure to notify the Distributor of any claim shall not relieve the Distributor from any liability which it may have to the Trust Affiliate against whom the action is brought otherwise than on account of its indemnity agreement contained in this paragraph. The Distributor shall be entitled to participate at its own expense in the defense or, if it so elects, to assume the defense of any suit brought to enforce the claim, but if the Distributor elects to assume the defense, the defense shall be conducted by counsel chosen by it and satisfactory to the Trust, its officers and Board and to any controlling person or persons, defendant or defendants in the suit. In the event that Distributor elects to assume the defense of any suit and retain counsel, the Trust or controlling person or persons, defendant or defendants in the suit, shall bear the fees and expenses of any additional counsel retained by them. If the Distributor does not elect to assume the defense of any suit, it will reimburse the Trust, its officers and Board or controlling person or persons, defendant or defendants in the suit, for the reasonable fees and expenses of any counsel retained by them.

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The Distributor agrees to notify the Trust promptly of the commencement of any litigation or proceedings against it in connection with the issuance and sale of any of the shares.

(c) No indemnified party shall settle any claim against it for which it intends to seek indemnification from the indemnifying party, under the terms of section 6(a) or 6(b) above, without the prior written notice to and consent from the indemnifying party, which consent shall not be unreasonably withheld. No indemnified or indemnifying party shall settle any claim unless the settlement contains a full release of liability with respect to the other party in respect of such action. This section 6 shall survive the termination of this Agreement.

7. Representations.

(a) The Distributor represents and warrants that (i) it is duly organized as a Colorado corporation and is and at all times will remain duly authorized and licensed to carry out its services as contemplated herein; (ii) the execution, delivery and performance of this Agreement are within its power and have been duly authorized by all necessary action; and (iii) its entering into this Agreement or providing the services contemplated hereby does not conflict with or constitute a default or require a consent under or breach of any provision of any agreement or document to which the Distributor is a party or by which it is bound and (iv) it is registered as a broker-dealer under the 1934 Act and is a member of the NASD.

(b) The Trust represents and warrants that (i) it is duly organized as a Massachusetts trust and is and at all times will remain duly authorized to carry out its obligations as contemplated herein; (ii) it is registered as an investment company under the 1940 Act; (iii) the execution, delivery and performance of this Agreement are within its power and have been duly authorized by all necessary action; and (iv) its entering into this Agreement does not conflict with or constitute a default or require a consent under or breach of any provision of any agreement or document to which the Trust is a party or by which it is bound.

8. Duration, Termination and Amendment.

(a) This Agreement shall be effective on the date set forth above and unless terminated as provided herein, shall continue for one year from its effective date, and thereafter from year to year, provided such continuance is approved annually by the vote of a majority of the Board of Trustees, and by the vote of those Trustees who are not "interested persons" of the Trust (the "Independent Trustees") and, if a plan under Rule 12b-1 under the 1940 Act is in effect, by the vote of those Trustees who are not "interested persons" of the Trust and who are not parties to such plan or this Agreement and have no financial interest in the operation of such plan or in any agreements related to such plan, cast in person at a meeting called for the purpose of voting on the approval. This Agreement may be terminated at any time, without the payment of any penalty, as to each Fund (i) by vote of a majority of the Independent Trustees or (ii) by vote of a majority (as defined in the 1940 Act) of the outstanding voting securities of the Fund, on at least sixty (60) days prior written notice to the Distributor. In addition, this Agreement may be terminated at any time by the Distributor upon at least sixty (60) days prior written notice to the Trust. This Agreement shall automatically terminate in the event of its assignment. As used in this paragraph, the terms "assignment" and "interested persons" shall have the respective meanings specified in the 1940 Act.

(b) During such period as the Distributor receives compensation pursuant to the 12b-1 Plan, and this Agreement constitutes a Rule 12b-1 Plan related agreement, (i) any material amendment to this Agreement requires the approval provided for in paragraph (a) with respect to annual renewals of this

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Agreement, and (ii) any amendment that materially increases the amount to be spent for distribution services requires the additional approval of the majority of the Trust's outstanding voting securities (as defined in the 1940 Act) of each affected Fund; and (iii) the selection and nomination of those Trustees who are not "interested persons" (as defined in the 1940 Act) of the Trust shall be committed to the discretion of the Trustees of the Trust who are not such "interested persons" of the Trust;

(c) No provision of this Agreement may be changed, waived, discharged or terminated except by an instrument in writing signed by the party against which an enforcement of the change, waiver, discharge or termination is sought.

9. Notice. Any notice or other communication authorized or required by this Agreement to be given to either party shall be in writing and deemed to have been given when delivered in person or by confirmed facsimile, or posted by certified mail, return receipt requested, to the following address (or such other address as a party may specify by written notice to the other): if to the Distributor: ALPS Distributors, Inc., 1625 Broadway, Suite 2200, Denver, CO 80202, Attn.: General Counsel, fax: (303) 623-7850; if to the Trust: State Street Bank and Trust Company, Attn.: Fund Administration Legal Department, P.O. Box 1713, Boston, MA 02105-1713 fax: (617) 662-3805.

10. Limitation of Liability. The Distributor is expressly put on notice of the limitation of shareholder liability as set forth in the Declaration of Trust of the Trust and agrees that the obligations assumed by the Trust under this contract shall be limited in all cases to the Trust and its assets. The Distributor shall not seek satisfaction of any such obligation from the shareholders or any shareholder of the Trust, nor shall the Distributor seek satisfaction of any such obligation from the Trustees or any individual Trustee of the Trust. The Distributor understands that the rights and obligations of each series of shares of the Trust under the Declaration of Trust are separate and distinct from those of any and all other series.

11. Choice of Law. This Agreement shall be governed by, and construed in accordance with, the laws of The Commonwealth of Massachusetts, without giving effect to the choice of laws provisions thereof.

12. Counterparties. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument.

13. Severability. If any provisions of this Agreement shall be held or made invalid, in whole or in part, then the other provisions of this Agreement shall remain in force. Invalid provisions shall, in accordance with this Agreement's intent and purpose, be amended, to the extent legally possible, by valid provisions in order to effectuate the intended results of the invalid provisions.

14. Insurance. The Distributor will maintain at its expense an errors and omissions insurance policy that covers services by the Distributor hereunder.

15. Segregation of Fees and Expenses. Amounts paid by each Fund to the Distributor under its Rule 12b-1 Plan either for distribution related services or shareholder services shall not be used to pay for the distribution of Shares of, or shareholder servicing in respect of, any other Fund. However, fees under the Rule 12b-1 Plan attributable to the Trust as a whole shall be allocated to each Fund according to the method adopted by the Trust's Board of Trustees. Fees attributable to the Trust as a whole shall include any amounts payable under the Rule 12b-1 Plan to the Distributor for its services rendered hereunder. The Distributor's allocation of such Rule 12b-1 Plan fees shall be subject to review by the Trust's Board of Trustees.

7

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed by their officers designated below as of the date first set forth above.

THE STATE STREET INSTITUTIONAL
INVESTMENT TRUST

By: /s/ James. Ross
    ------------------------------------
Name: James Ross
Title: President

ALPS DISTRIBUTORS, INC.

By: /s/ Jeremy O. May
    ------------------------------------
Name: Jeremy O. May
Title: Managing Director

8

Annex I

FUND

State Street Equity 500 Index Fund (Investor, Service and Class R Shares) State Street Equity 400 Index Fund
State Street Equity 2000 Index Fund
State Street Aggregate Bond Index Fund
State Street Money Market Fund
State Street U.S. Government Money Market Fund

As of December 31, 2005

9

EXHIBIT (H)(4)

FORM OF MASTER FEEDER PARTICIPATION AGREEMENT

BETWEEN

STATE STREET INSTITUTIONAL INVESTMENT TRUST

AND

STATE STREET MASTER FUNDS

DATED AS OF

MARCH 30, 2004

AGREEMENT

THIS AGREEMENT is made and entered into as of the 30th day of March 2004, by and between State Street Institutional Investment Trust (the "Company"), on behalf of the State Street Equity 500 Index Fund (the "Feeder Fund") and State Street Master Funds (the "Trust"), a trust organized under the common law of the Commonwealth of Massachusetts, on behalf of its State Street Equity 500 Index Portfolio (the "Master Portfolio").

WITNESSETH

WHEREAS, the Feeder Fund and the Master Portfolio are each open-end management investment companies and the Feeder Fund and the Master Portfolio have the same investment objectives and substantively the same investment policies;

WHEREAS, the Feeder Fund desires to invest all of the its investable assets in the Master Portfolio in exchange for a beneficial interest in the Master Portfolio (the "Investment") on the terms and conditions set forth in this Agreement;

NOW, THEREFORE, in consideration of the foregoing, the mutual promises herein made and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties agree as follows:

I
THE INVESTMENT

1.1 The Feeder Fund will invest all of its investable assets in the Master Portfolio and, in exchange therefor, the Master Portfolio agrees to issue to the Feeder Fund a beneficial interest in the Master Portfolio equal in value to the net value of the assets of the Feeder Fund conveyed to the Master Portfolio (the "Account"). The Feeder Fund may add to or reduce its investment in the Master Portfolio in the manner described in the Master Portfolio's registration statement on Form N-1A, as it may be amended from time to time (the "Master Portfolio's N-1A"). The Feeder Fund's aggregate interest in the Master Portfolio would then be recomputed in accordance with the method described in the Master Portfolio's N-1A.

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1.2 On each date of Investment, the Feeder Fund shall authorize the Feeder Fund's custodian to deliver all of the assets held by such custodian to the Master Portfolio's custodian. The Master Portfolio's custodian shall acknowledge its acceptance of the assets. In addition, each party shall deliver to the other such bills of sale, checks, assignments, securities instruments, receipts or other documents as such other party or its counsel may reasonably request.

II
REPRESENTATIONS AND WARRANTIES

2.1 The Company on behalf of the Feeder Fund represents and warrants to the Trust and the Master Portfolio (which representations and warranties shall be deemed made at and as of this date and at and as of all times when this Agreement is in effect) that:

(a) The Feeder Fund is a series of State Street Institutional Investment Trust, a trust duly organized and validly existing under the Commonwealth of Massachusetts, and has the requisite power and authority to own its property and conduct its business as now being conducted and as proposed to be conducted pursuant to this Agreement.

(b) The execution and delivery of this Agreement by the Feeder Fund and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of the Feeder Fund by the Company's Board of Trustees and no other action or proceeding is necessary for the execution and delivery of this Agreement by the Company, the performance by the Company of its obligations hereunder and the consummation by the Feeder Fund of the transactions contemplated hereby. This Agreement has been duly executed and delivered by the Feeder Fund and constitutes a legal, valid and binding obligation of the Feeder Fund, enforceable against it in accordance with its terms.

(c) The Feeder Fund is not under the jurisdiction of a court in a proceeding under Title 11 of the United States Code (the "Bankruptcy Code") or similar case within the meaning of Section 368(a) (3) (A) of the Bankruptcy Code.

(d) The fiscal year end for the Feeder Fund is December 31.

(e) The Feeder Fund has duly filed all forms, reports, proxy statements and other documents (collectively, the "SEC Filings") required to be filed under the Securities Act of 1933, as amended (the "1933 Act"), the Securities Exchange Act of 1934 (the "1934 Act") or the Investment Company Act of 1940, as amended (the "1940 Act" and, together with the 1933 Act and the 1934 Act, the "Securities Laws") in connection with the registration of its shares, any meetings of its shareholders and its registration as an investment company. The SEC Filings were prepared in accordance with the requirements of the Securities Laws, as applicable, and the rules and regulations of the Securities and Exchange Commission (the "SEC") thereunder, and did not at the time of their filing contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(f) The Feeder Fund has duly registered as an open-end management investment company under the 1940 Act and the Feeder Fund and its shares are registered or qualified in any states where such registration or qualification is necessary and such registrations or qualifications are in full force and effect. The Feeder Fund is and will at all times when it owns or purchases interests in the Master Portfolio be registered as an open-end investment company under the 1940 Act.

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(g) The Feeder Fund understands and agrees that the interests in the Master Portfolio (the "Interests") have not been registered and will not be registered under the 1933 Act or any state securities law, and that the Interests offered and the offering of the Interests have not been approved, disapproved, or passed on by any federal or state regulatory agency or commission, securities or commodities exchange, or other self-regulatory organization. The sale of interests is being made privately by the Master Portfolio pursuant to the private placement exemption from registration provided by Section 4(2) of the 1933 Act.

(h) The Feeder Fund acknowledges that it has received copies of the Offering Memorandum of the Master Portfolio (the "Memorandum") and of the Master Portfolio's Declaration of Trust and By-Laws. The Feeder Fund has read, understands, and is fully familiar with each of those documents and has received adequate information concerning all matters that the Feeder Fund considers material to a decision to purchase the Interests.

(i) The Interests subscribed for will be acquired solely by and for the account of the Feeder Fund, solely for investment, and are not being purchased for resale or distribution. The Feeder Fund has no existing or contemplated agreement or arrangement with any person to sell, exchange, transfer, assign, pledge, or otherwise dispose of the interests. The Feeder Fund acknowledges and agrees that the interests are non-transferable.

(j) The Feeder Fund has relied solely upon the Memorandum, the advice of its tax or other advisers, and independent investigations made by the Feeder Fund in purchasing the Interests. No representations or agreements other than those set forth in the Memorandum have been made to the Feeder Fund by the Master Portfolio.

(k) The Feeder Fund agrees to notify the Trust promptly if there is any change with respect to any of the information, representations, or warranties contained herein and to provide such further information as the Trust may reasonably request.

(l) The Feeder Fund acknowledges that (i) it is a "financial institution" as defined in the Bank Secrecy Act (the "BSA") and/or (ii) it relies on service providers that are "financial institutions" to perform functions of handling customer applications, creating shareholder accounts, receiving funds, processing transactions for customer accounts, and withdrawing and distributing funds from customer accounts. The Feeder Fund also acknowledges that it, and/or its service providers on its behalf, are required to comply with the BSA and the USA PATRIOT Act of 2001 (the "AML Laws").

2.2 The Trust on behalf of the Master Portfolio represents and warrants to the Company and the Feeder Fund (which representations and warranties shall be deemed made at and as of this date and at all times when this Agreement is in effect) that:

(a) The Master Portfolio is a series of the State Street Master Funds, a trust duly organized and validly existing under the Commonwealth of Massachusetts, which has the requisite power and authority to own its property and conduct its business as now being conducted and as proposed to be conducted pursuant to this Agreement.

(b) The execution and delivery of this Agreement by the Trust and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of the Trust by its Board of Trustees and no other action or proceeding is necessary for the execution and delivery of this Agreement by the Trust, the performance by the Trust of its obligations hereunder and the consummation by the Trust of the transactions contemplated hereby. This Agreement

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has been duly executed and delivered by the Trust and constitutes a legal, valid and binding obligation of the Trust, enforceable against it in accordance with its terms.

(c) The issuance by the Master Portfolio of the Interests in exchange for the Investment by the Feeder Fund of its assets has been duly authorized by all necessary action on the part of the Board of Trustees of the Trust. When issued in accordance with the terms of this Agreement, the Interests will be validly issued, fully paid and non-assessable by the Master Portfolio.

(d) The Master Portfolio is not under the jurisdiction of a court in a proceeding under Title 11 of the Bankruptcy Code or similar case within the meaning of Section 368(a)(3)(A) of the Bankruptcy Code.

(e) The fiscal year end of the Master Portfolio is December 31.

(f) The Master Portfolio has duly filed all SEC Filings required to be filed with the SEC pursuant to the 1934 Act and the 1940 Act in connection with any meetings of its investors and its registration as an investment company. The SEC Filings were prepared in accordance with the requirements of the Securities Laws, as applicable, and the rules and regulations of the SEC thereunder, and do not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(g) The Master Portfolio is duly registered as an open-end management investment company under the 1940 Act and such registration is in full force and effect.

III
COVENANTS AND INDEMNIFICATION

3.1 The Feeder Fund covenants that:

(a) The Feeder Fund will own no investment security other than its Account in the Master Portfolio for all periods during which this Agreement is in effect.

(b) If requested to vote on matters pertaining to the Master Portfolio, the Feeder Fund will (i) call a meeting of shareholders of the Feeder Fund for the purpose of seeking instructions from shareholders regarding such matters, (ii) vote the Feeder Fund's Interests proportionally as instructed by Feeder Fund shareholders, and (iii) vote the Feeder Fund's Interests with respect to the shares held by Feeder Fund shareholders who do not give voting instructions in the same proportion as the shares of Feeder Fund shareholders who do give voting instructions. The Feeder Fund will hold each such meeting of Feeder Fund shareholders in accordance with a timetable reasonably established by the Master Portfolio.

(c) The Feeder Fund will furnish the Master Portfolio, at least five
(5) business days prior to filing or first use, as the case may be, with drafts of amendments to its registration statement on Form N-lA and prospectus supplements or amendments relating to the Feeder Fund. The Feeder Fund will furnish the Master Portfolio with any proposed advertising or sales literature relating to the Feeder Fund at least three (3) business days prior to filing or first use; provided, however, that such advance notice shall not be required for advertising or sales literature that merely references the name of the Feeder Fund. The Feeder Fund agrees that it will include in all such Feeder Fund documents any disclosures that may be required by law and it will include in all such Feeder Fund documents any material comments reasonably made by the Master Portfolio and its counsel. The Master Portfolio will,

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however, in no way be liable for any errors or omissions in such documents, whether or not it makes any objection thereto, except to the extent such errors or omissions result from information provided in writing by the Master Portfolio. The Feeder Fund will not make any other written or oral representation about the Master Portfolio without its prior written consent.

(d) The Feeder Fund agrees to comply with the AML Laws and to provide such information and documentation evidencing compliance with the AML Laws as may be requested by the Master Portfolio from time to time.

3.2 Indemnification by Feeder Fund.

(a) Feeder Fund will indemnify and hold harmless the Master Portfolio, and the Trust and its respective trustees, directors, officers and employees and each other person who controls the Master Portfolio, as the case may be, within the meaning of Section 15 of the 1933 Act (each, a "Covered Person" and collectively, "Covered Persons"), against any and all losses, claims, demands, damages, liabilities and expenses (each, a "Liability" and collectively, the "Liabilities") (including the reasonable cost of investigating and defending against any claims therefor and any counsel fees incurred in connection therewith), joint or several, which

(i) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any registration statement, any prospectus, or any amendment thereof or supplement thereto, or any advertisement or sales literature, or any other document or publication filed, created, or published or otherwise disseminated by the Feeder Fund, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that the Feeder Fund will not be liable in any such case to the extent that such Liability arises out of or is based upon any untrue statement or omission in or from any thereof in reliance upon and in conformity with written information furnished to the Feeder Fund by the Master Portfolio specifically for use therein;

(ii) result from the failure of any representation or warranty made by the Company on behalf of the Feeder Fund to be accurate when made or the failure of the Company or the Feeder Fund to perform any covenant contained herein or to otherwise comply with the terms of this Agreement; or

(iii) arise out of any failure of the Feeder Fund or any director, officer, employee or agent of the Company, to comply with any applicable law;

provided, however, that in no case shall the Feeder Fund be liable with respect to any claim made against any Covered Person unless the party shall have notified the Feeder Fund in writing of the nature of the claim within a reasonable time after the summons, other first legal process or formal or informal initiation of a regulatory investigation or proceeding shall have been served upon or provided to a Covered Person, or any federal, state or local tax deficiency has come to the attention of the the Master Portfolio or a Covered Person. Failure to notify the Feeder Fund of such claim shall not relieve it from any liability that it may have to any party otherwise than on account of the indemnification contained in this Section.

(b) The Feeder Fund will be entitled to participate at its own expense in the defense or, if it so elects, to assume the defense of any suit brought to enforce any such liability, but, if the Feeder Fund elects to assume the defense, such defense shall be conducted by counsel chosen by the Feeder Fund and reasonably acceptable to the Master Portfolio. In the event the Feeder Fund elects to assume the defense of any such suit and retain such counsel, each Covered Person and any other defendant or defendants may retain additional counsel, but shall bear the fees and expenses of such counsel unless (A)

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the Feeder Fund shall have specifically authorized the retaining of such counsel or (B) the parties to such suit include any Covered Person and the Feeder Fund, and any such Covered Person has been advised by counsel that one or more legal defenses may be available to it that may not be available to the Feeder Fund, in which case the Feeder Fund shall not be entitled to assume the defense of such suit notwithstanding its obligation to bear the fees and expenses of such counsel. The Feeder Fund shall not be liable to indemnify any Covered Person for any settlement of any claim effected without the Feeder Fund's written consent, which consent shall not be unreasonably withheld or delayed. The indemnities set forth in paragraph (a) will be in addition to any liability that the Feeder Fund might otherwise have to a Covered Person.

3.3 Indemnification by the Master Portfolio.

(a) The Master Portfolio will indemnify and hold harmless the Feeder Fund and the Company and its respective directors, officers and employees and each other person who controls the Feeder Fund, as the case may be, within the meaning of Section 15 of the 1933 Act (each, a "Covered Person" and collectively, "Covered Persons"), against any and all losses, claims, demands, damages, liabilities and expenses (each, a "Liability" and collectively, the "Liabilities") (including the reasonable costs of investigating and defending against any claims therefor and any counsel fees incurred in connection therewith), joint or several, whether incurred directly by the Feeder Fund or through the Feeder Fund's Investment in the Master Portfolio, which

(i) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in the Master Portfolio's N-1A, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that the Master Portfolio will not be liable in any such case to the extent that any such Liability arises out of or is based upon any untrue statement or omission in or from the Master Portfolio's N-1A in reliance upon and in conformity with written information furnished to the Master Portfolio by the Feeder Fund specifically for use therein (for this purpose, information of any kind contained in any filing by the Feeder Fund with the Securities and Exchange Commission being deemed to have been so furnished to the Master Portfolio);

(ii) arise out of or are based upon a materially inaccurate calculation of the Master Portfolio's net asset value (whether by the Master Portfolio or any party retained for that purpose);

(iii) result from the failure of any representation or warranty made by the Master Portfolio to be accurate when made or the failure of the Master Portfolio to perform any covenant contained herein or to otherwise comply with the terms of this Agreement; or

(iv) arise out of any claim that the use of the names "Standard & Poor's," "S&P," "Standard & Poor's 500," "S&P 500" or 500" by the Master Portfolio violates any license or infringes upon any trademark;

provided, however, that in no case shall the Master Portfolio be liable with respect to any claim made against any such Covered Person unless such Covered Person shall have notified the Master Portfolio in writing of the nature of the claim within a reasonable time after the summons, other first legal process or formal or informal initiation of a regulatory investigation or proceeding shall have been served upon or provided to a Covered Person or any federal, state or local tax deficiency has come to the attention of the Feeder Fund or a Covered Person. Failure to notify the Master Portfolio of such claim shall not relieve it from any liability that it may have to any Covered Person otherwise than on account of the indemnification contained in this paragraph.

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(b) The Master Portfolio will be entitled to participate at its own expense in the defense or, if it so elects, to assume the defense of any suit brought to enforce any such liability, but, if the Master Portfolio elects to assume the defense, such defense shall be conducted by counsel chosen by the Master Portfolio. In the event that the Master Portfolio elects to assume the defense of any such suit and retain such counsel, each Covered Person and any other defendant or defendants may retain additional counsel, but shall bear the fees and expenses of such counsel unless (A) the Master Portfolio shall have specifically authorized the retaining of such counsel or (B) the parties to such suit include any Covered Person and the Master Portfolio, and any such Covered Person has been advised by counsel that one or more legal defenses may be available to it that may not be available to the Master Portfolio, in which case the Master Portfolio shall not be entitled to assume the defense of such suit notwithstanding its obligation to bear the fees and expenses of such counsel. The Master Portfolio shall not be liable to indemnify any Covered Person for any settlement of any claim affected without the Master Portfolio's written consent, which consent shall not be unreasonably withheld or delayed. The indemnities set forth in paragraph (a) will be in addition to any liability that the Master Portfolio might otherwise have to a Covered Person.

3.4 Allocation of Losses.

(a) If the indemnification provided for in Section 3.2 or Section 3.3 is for any reason unavailable to or insufficient to hold harmless a Covered Person in respect of any losses, claims, demands, damages, liabilities, or expenses referred to therein, then each indemnifying party shall contribute to the aggregate amount of such any losses, claims, demands, damages, liabilities, or expenses incurred by such Covered Person in such proportion as is appropriate to reflect the relative fault of the Feeder Fund and the Master Portfolio in connection with the statements or omissions or other action or failure to act which resulted in such losses, liabilities, claims, damages, or expenses, as well as any other relevant equitable considerations.

(b) In the case of any such untrue or alleged untrue statement of a material fact or omission or alleged omission to state a material fact, the relative fault of the Feeder Fund and the Master Portfolio shall be determined by reference to, among other things, whether any such untrue statement or alleged untrue statement or omission or alleged omission related to information supplied by the Feeder Fund or the Master Portfolio and the parties' relative intent, knowledge, access to information, and opportunity to correct or prevent such statement or omission.

(c) The Feeder Fund and the Master Portfolio agree that it would not be just and equitable if contribution pursuant to this Section 3.4 were determined by any method of allocation which does not take account of the equitable considerations referred to above in this Section 3.4. The aggregate amount of losses, claims, demands, damages, liabilities, and expenses incurred by a Covered Person and referred to above in this Section 3.4 shall be deemed to include any legal or other expenses reasonably incurred by such Covered Person in investigating, preparing, or defending against any litigation or any investigation or proceeding or any such claims and reasonable counsel fees incurred in connection therewith.

(d) For purposes of this Section 3.4, each person, if any, who controls the Feeder Fund or the Master Portfolio within the meaning of Section 15 of the 1933 Act or Section 20 of the Securities Exchange Act of 1934, as amended, shall have the same rights to contribution as the Feeder Fund or the Master Portfolio, as the case may be, and each director or trustee, officer, or employee of the Trust or the Company and each officer thereof who signed a registration statement shall have the same rights to contribution as the Feeder Fund or the Master Portfolio, as the case may be.

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IV
ADDITIONAL AGREEMENTS

4.1 Each party agrees that it shall hold in strict confidence all data and information obtained from the other party (unless such information is or becomes readily ascertainable from public or published information or trade sources) and shall ensure that its officers, employees and authorized representatives do not disclose such information to others without the prior written consent of the party from whom it was obtained, except if disclosure is required by the SEC, any other regulatory body or the Feeder Fund's or Master Portfolio's respective auditors, or in the opinion of counsel such disclosure is required by law, and then only with as much prior written notice to the other party as is practical under the circumstances.

4.2 No party shall issue any press release or otherwise make any public statements with respect to the matters covered by this Agreement without the prior consent of the other parties hereto, which consent shall not be unreasonably withheld; provided, however, that consent shall not be required if, in the opinion of counsel, such disclosure is required by law, provided further, however, that the party making such disclosure shall provide the other parties hereto with as much prior written notice of such disclosure as is practical under the circumstances.

V
TERMINATION, AMENDMENT AND WAIVER

5.1 Termination.

(a) This Agreement may be terminated by the Company upon five (5) business days notice to the Trust.

(b) This Agreement may be terminated at any time by the Company by withdrawing all of the Feeder Fund's Interest in the Master Portfolio.

(c) This Agreement may be terminated on not less than 120 days' prior written notice by the Trust to the Company.

(d) This Agreement may be terminated at any time immediately upon written notice to the other parties in the event that formal proceedings are instituted against another party to this Agreement by the SEC or any other regulatory body, provided that the terminating party has a reasonable belief that the institution of the proceeding is not without foundation and will have a material adverse impact on the terminating party.

(e) The indemnification obligations set forth in Article III and the confidentiality provisions in Section 4.1 shall survive the termination of this Agreement.

5.2 This Agreement may be amended, modified or supplemented at any time in such manner as may be mutually agreed upon in writing by the parties.

VI
GENERAL PROVISIONS

6.1 All notices and other communications given or made pursuant hereto shall to in writing and shall be deemed to have been duly given or made when actually received in person or by fax, or three

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days after being sent by certified or registered United States mail, return receipt requested, postage prepaid, addressed as follows:

If to the Feeder Fund:

State Street Master Funds
c/o State Street Bank and Trust Company
P.O. Box 5049
Boston, MA 02206
Attn: Julie Tedesco

If to the Master Portfolio:

State Street Master Funds
c/o State Street Bank and Trust Company
P.O. Box 5049
Boston, MA 02206
Attn: Julie Tedesco

Either party to this Agreement may change the identity of the person to receive notice by providing written notice thereof to all other parties to the Agreement.

6.2 Unless stated otherwise herein, all costs and expenses associated with this Agreement and the transactions contemplated hereby shall be paid by the party incurring such costs and expenses.

6.3 The headings and captions contained in this Agreement are for reference purposes only and shall not affect in any way the meaning or interpretation of this Agreement.

6.4 If any term or other provision of this Agreement is invalid, illegal or incapable of being enforced by any rule of law, or public policy, all other conditions and provisions of this Agreement shall nevertheless remain in full force and effect so long as the economic or legal substance of the transactions contemplated hereby is not affected in any manner adverse to any party. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto shall negotiate in good faith to modify this Agreement so as to effect the original intent of the parties as closely as possible in an acceptable manner to the end that the transactions contemplated hereby are fulfilled to the extent possible.

6.5 This Agreement and the agreements and other documents delivered pursuant hereto set forth the entire understanding between the parties concerning the subject matter of this Agreement and incorporate or supersede all prior negotiations and understandings. There are no covenants, promises, agreements, conditions or understandings, either oral or written, between them relating to the subject matter of this Agreement other than those set forth herein.

6.6 Each and all of the provisions of this Agreement shall be binding upon and inure to the benefit of the parties hereto and, except as otherwise specifically provided in this Agreement, their respective successors and assigns. Notwithstanding the foregoing, no party shall make any assignment of this Agreement or any rights or obligations hereunder without the written consent of all other parties.

6.7 This Agreement shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts without giving effect to the choice of law or conflicts of law provisions thereof.

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6.8 This Agreement may be executed in any number of counterparts, all of which shall constitute one and the same instrument, and any party hereto may execute this Agreement by signing one or more counterparts.

6.9 Nothing herein expressed or implied is intended or shall be construed to confer upon or give any person, other than the parties hereto and their successors or assigns, any rights or remedies under or by reason of this Agreement.

6.10 Any uncertainty or ambiguity existing herein shall not presumptively be interpreted against any party, but shall be interpreted according to the application of the rules of interpretation for arm's length agreements.

6.11 Each party expressly acknowledges the provision in the Articles of Incorporation of the Company and the Declaration of Trust of the Trust limiting the personal liability of shareholders and the officers and trustees of the Feeder Fund and the Master Portfolio, respectively.

6.12 The parties hereto agree and acknowledge that (a) the Company has entered into this Agreement solely on behalf of the Feeder Fund and that no other party shall have any obligation hereunder with respect to any liability of the Feeder Fund arising hereunder; (b) the Trust has entered into this Agreement solely on behalf of the Master Portfolio and that no other series of the Trust shall have any obligation hereunder with respect to any liability of the Master Portfolio arising hereunder; and (c) no series or feeder participant of the Master Portfolio shall be liable to any other series or feeder participant of the Master Portfolio.

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by their respective officers, thereunto duly authorized, as of the date first written above.

STATE STREET INSTITUTIONAL INVESTMENT
TRUST


By: Karen D. Gillogly Its: Treasurer

STATE STREET MASTER FUNDS


By: Donald A. Gignac Its: President

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EXHIBIT (H)(5)

FORM OF MASTER FEEDER PARTICIPATION AGREEMENT

BETWEEN

STATE STREET INSTITUTIONAL INVESTMENT TRUST

AND

STATE STREET MASTER FUNDS

DATED AS OF

MARCH 30, 2004

AGREEMENT

THIS AGREEMENT is made and entered into as of the 30th day of March 2004, by and between State Street Institutional Investment Trust (the "Company"), on behalf of the State Street Institutional Liquid Reserves Fund (the "Feeder Fund") and State Street Master Funds (the "Trust"), a trust organized under the common law of the Commonwealth of Massachusetts, on behalf of its State Street Money Market Portfolio (the "Master Portfolio").

WITNESSETH

WHEREAS, the Feeder Fund and the Master Portfolio are each open-end management investment companies and the Feeder Fund and the Master Portfolio have the same investment objectives and substantively the same investment policies;

WHEREAS, the Feeder Fund desires to invest all of the its investable assets in the Master Portfolio in exchange for a beneficial interest in the Master Portfolio (the "Investment") on the terms and conditions set forth in this Agreement;

NOW, THEREFORE, in consideration of the foregoing, the mutual promises herein made and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties agree as follows:

I
THE INVESTMENT

1.1 The Feeder Fund will invest all of its investable assets in the Master Portfolio and, in exchange therefor, the Master Portfolio agrees to issue to the Feeder Fund a beneficial interest in the Master Portfolio equal in value to the net value of the assets of the Feeder Fund conveyed to the Master Portfolio (the "Account"). The Feeder Fund may add to or reduce its investment in the Master Portfolio in the manner described in the Master Portfolio's registration statement on Form N-1A, as it may be amended from time to time (the "Master Portfolio's N-1A"). The Feeder Fund's aggregate interest in the Master Portfolio would then be recomputed in accordance with the method described in the Master Portfolio's N-1A.

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1.2 On each date of Investment, the Feeder Fund shall authorize the Feeder Fund's custodian to deliver all of the assets held by such custodian to the Master Portfolio's custodian. The Master Portfolio's custodian shall acknowledge its acceptance of the assets. In addition, each party shall deliver to the other such bills of sale, checks, assignments, securities instruments, receipts or other documents as such other party or its counsel may reasonably request.

II
REPRESENTATIONS AND WARRANTIES

2.1 The Company on behalf of the Feeder Fund represents and warrants to the Trust and the Master Portfolio (which representations and warranties shall be deemed made at and as of this date and at and as of all times when this Agreement is in effect) that:

(a) The Feeder Fund is a series of State Street Institutional Investment Trust, a trust duly organized and validly existing under the Commonwealth of Massachusetts, and has the requisite power and authority to own its property and conduct its business as now being conducted and as proposed to be conducted pursuant to this Agreement.

(b) The execution and delivery of this Agreement by the Feeder Fund and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of the Feeder Fund by the Company's Board of Trustees and no other action or proceeding is necessary for the execution and delivery of this Agreement by the Company, the performance by the Company of its obligations hereunder and the consummation by the Feeder Fund of the transactions contemplated hereby. This Agreement has been duly executed and delivered by the Feeder Fund and constitutes a legal, valid and binding obligation of the Feeder Fund, enforceable against it in accordance with its terms.

(c) The Feeder Fund is not under the jurisdiction of a court in a proceeding under Title 11 of the United States Code (the "Bankruptcy Code") or similar case within the meaning of Section 368(a) (3) (A) of the Bankruptcy Code.

(d) The fiscal year end for the Feeder Fund is December 31.

(e) The Feeder Fund has duly filed all forms, reports, proxy statements and other documents (collectively, the "SEC Filings") required to be filed under the Securities Act of 1933, as amended (the "1933 Act"), the Securities Exchange Act of 1934 (the "1934 Act") or the Investment Company Act of 1940, as amended (the "1940 Act" and, together with the 1933 Act and the 1934 Act, the "Securities Laws") in connection with the registration of its shares, any meetings of its shareholders and its registration as an investment company. The SEC Filings were prepared in accordance with the requirements of the Securities Laws, as applicable, and the rules and regulations of the Securities and Exchange Commission (the "SEC") thereunder, and did not at the time of their filing contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(f) The Feeder Fund has duly registered as an open-end management investment company under the 1940 Act and the Feeder Fund and its shares are registered or qualified in any states where such registration or qualification is necessary and such registrations or qualifications are in full force and effect. The Feeder Fund is and will at all times when it owns or purchases interests in the Master Portfolio be registered as an open-end investment company under the 1940 Act.

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(g) The Feeder Fund understands and agrees that the interests in the Master Portfolio (the "Interests") have not been registered and will not be registered under the 1933 Act or any state securities law, and that the Interests offered and the offering of the Interests have not been approved, disapproved, or passed on by any federal or state regulatory agency or commission, securities or commodities exchange, or other self-regulatory organization. The sale of interests is being made privately by the Master Portfolio pursuant to the private placement exemption from registration provided by Section 4(2) of the 1933 Act.

(h) The Feeder Fund acknowledges that it has received copies of the Offering Memorandum of the Master Portfolio (the "Memorandum") and of the Master Portfolio's Declaration of Trust and By-Laws. The Feeder Fund has read, understands, and is fully familiar with each of those documents and has received adequate information concerning all matters that the Feeder Fund considers material to a decision to purchase the Interests.

(i) The Interests subscribed for will be acquired solely by and for the account of the Feeder Fund, solely for investment, and are not being purchased for resale or distribution. The Feeder Fund has no existing or contemplated agreement or arrangement with any person to sell, exchange, transfer, assign, pledge, or otherwise dispose of the interests. The Feeder Fund acknowledges and agrees that the interests are non-transferable.

(j) The Feeder Fund has relied solely upon the Memorandum, the advice of its tax or other advisers, and independent investigations made by the Feeder Fund in purchasing the Interests. No representations or agreements other than those set forth in the Memorandum have been made to the Feeder Fund by the Master Portfolio.

(k) The Feeder Fund agrees to notify the Trust promptly if there is any change with respect to any of the information, representations, or warranties contained herein and to provide such further information as the Trust may reasonably request.

(l) The Feeder Fund acknowledges that (i) it is a "financial institution" as defined in the Bank Secrecy Act (the "BSA") and/or (ii) it relies on service providers that are "financial institutions" to perform functions of handling customer applications, creating shareholder accounts, receiving funds, processing transactions for customer accounts, and withdrawing and distributing funds from customer accounts. The Feeder Fund also acknowledges that it, and/or its service providers on its behalf, are required to comply with the BSA and the USA PATRIOT Act of 2001 (the "AML Laws").

2.2 The Trust on behalf of the Master Portfolio represents and warrants to the Company and the Feeder Fund (which representations and warranties shall be deemed made at and as of this date and at all times when this Agreement is in effect) that:

(a) The Master Portfolio is a series of the State Street Master Funds, a trust duly organized and validly existing under the Commonwealth of Massachusetts, which has the requisite power and authority to own its property and conduct its business as now being conducted and as proposed to be conducted pursuant to this Agreement.

(b) The execution and delivery of this Agreement by the Trust and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of the Trust by its Board of Trustees and no other action or proceeding is necessary for the execution and delivery of this Agreement by the Trust, the performance by the Trust of its obligations hereunder and the consummation by the Trust of the transactions contemplated hereby. This Agreement

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has been duly executed and delivered by the Trust and constitutes a legal, valid and binding obligation of the Trust, enforceable against it in accordance with its terms.

(c) The issuance by the Master Portfolio of the Interests in exchange for the Investment by the Feeder Fund of its assets has been duly authorized by all necessary action on the part of the Board of Trustees of the Trust. When issued in accordance with the terms of this Agreement, the Interests will be validly issued, fully paid and non-assessable by the Master Portfolio.

(d) The Master Portfolio is not under the jurisdiction of a court in a proceeding under Title 11 of the Bankruptcy Code or similar case within the meaning of Section 368(a)(3)(A) of the Bankruptcy Code.

(e) The fiscal year end of the Master Portfolio is December 31.

(f) The Master Portfolio has duly filed all SEC Filings required to be filed with the SEC pursuant to the 1934 Act and the 1940 Act in connection with any meetings of its investors and its registration as an investment company. The SEC Filings were prepared in accordance with the requirements of the Securities Laws, as applicable, and the rules and regulations of the SEC thereunder, and do not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(g) The Master Portfolio is duly registered as an open-end management investment company under the 1940 Act and such registration is in full force and effect.

III
COVENANTS AND INDEMNIFICATION

3.1 The Feeder Fund covenants that:

(a) The Feeder Fund will own no investment security other than its Account in the Master Portfolio for all periods during which this Agreement is in effect.

(b) If requested to vote on matters pertaining to the Master Portfolio, the Feeder Fund will (i) call a meeting of shareholders of the Feeder Fund for the purpose of seeking instructions from shareholders regarding such matters, (ii) vote the Feeder Fund's Interests proportionally as instructed by Feeder Fund shareholders, and (iii) vote the Feeder Fund's Interests with respect to the shares held by Feeder Fund shareholders who do not give voting instructions in the same proportion as the shares of Feeder Fund shareholders who do give voting instructions. The Feeder Fund will hold each such meeting of Feeder Fund shareholders in accordance with a timetable reasonably established by the Master Portfolio.

(c) The Feeder Fund will furnish the Master Portfolio, at least five
(5) business days prior to filing or first use, as the case may be, with drafts of amendments to its registration statement on Form N-lA and prospectus supplements or amendments relating to the Feeder Fund. The Feeder Fund will furnish the Master Portfolio with any proposed advertising or sales literature relating to the Feeder Fund at least three (3) business days prior to filing or first use; provided, however, that such advance notice shall not be required for advertising or sales literature that merely references the name of the Feeder Fund. The Feeder Fund agrees that it will include in all such Feeder Fund documents any disclosures that may be required by law and it will include in all such Feeder Fund documents any material comments reasonably made by the Master Portfolio and its counsel. The Master Portfolio will,

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however, in no way be liable for any errors or omissions in such documents, whether or not it makes any objection thereto, except to the extent such errors or omissions result from information provided in writing by the Master Portfolio. The Feeder Fund will not make any other written or oral representation about the Master Portfolio without its prior written consent.

(d) The Feeder Fund agrees to comply with the AML Laws and to provide such information and documentation evidencing compliance with the AML Laws as may be requested by the Master Portfolio from time to time.

3.2 Indemnification by Feeder Fund.

(a) Feeder Fund will indemnify and hold harmless the Master Portfolio, and the Trust and its respective trustees, directors, officers and employees and each other person who controls the Master Portfolio, as the case may be, within the meaning of Section 15 of the 1933 Act (each, a "Covered Person" and collectively, "Covered Persons"), against any and all losses, claims, demands, damages, liabilities and expenses (each, a "Liability" and collectively, the "Liabilities") (including the reasonable cost of investigating and defending against any claims therefor and any counsel fees incurred in connection therewith), joint or several, which

(i) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any registration statement, any prospectus, or any amendment thereof or supplement thereto, or any advertisement or sales literature, or any other document or publication filed, created, or published or otherwise disseminated by the Feeder Fund, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that the Feeder Fund will not be liable in any such case to the extent that such Liability arises out of or is based upon any untrue statement or omission in or from any thereof in reliance upon and in conformity with written information furnished to the Feeder Fund by the Master Portfolio specifically for use therein;

(ii) result from the failure of any representation or warranty made by the Company on behalf of the Feeder Fund to be accurate when made or the failure of the Company or the Feeder Fund to perform any covenant contained herein or to otherwise comply with the terms of this Agreement; or

(iii) arise out of any failure of the Feeder Fund or any director, officer, employee or agent of the Company, to comply with any applicable law;

provided, however, that in no case shall the Feeder Fund be liable with respect to any claim made against any Covered Person unless the party shall have notified the Feeder Fund in writing of the nature of the claim within a reasonable time after the summons, other first legal process or formal or informal initiation of a regulatory investigation or proceeding shall have been served upon or provided to a Covered Person, or any federal, state or local tax deficiency has come to the attention of the the Master Portfolio or a Covered Person. Failure to notify the Feeder Fund of such claim shall not relieve it from any liability that it may have to any party otherwise than on account of the indemnification contained in this Section.

(b) The Feeder Fund will be entitled to participate at its own expense in the defense or, if it so elects, to assume the defense of any suit brought to enforce any such liability, but, if the Feeder Fund elects to assume the defense, such defense shall be conducted by counsel chosen by the Feeder Fund and reasonably acceptable to the Master Portfolio. In the event the Feeder Fund elects to assume the defense of any such suit and retain such counsel, each Covered Person and any other defendant or defendants may retain additional counsel, but shall bear the fees and expenses of such counsel unless (A)

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the Feeder Fund shall have specifically authorized the retaining of such counsel or (B) the parties to such suit include any Covered Person and the Feeder Fund, and any such Covered Person has been advised by counsel that one or more legal defenses may be available to it that may not be available to the Feeder Fund, in which case the Feeder Fund shall not be entitled to assume the defense of such suit notwithstanding its obligation to bear the fees and expenses of such counsel. The Feeder Fund shall not be liable to indemnify any Covered Person for any settlement of any claim effected without the Feeder Fund's written consent, which consent shall not be unreasonably withheld or delayed. The indemnities set forth in paragraph (a) will be in addition to any liability that the Feeder Fund might otherwise have to a Covered Person.

3.3 Indemnification by the Master Portfolio.

(a) The Master Portfolio will indemnify and hold harmless the Feeder Fund and the Company and its respective directors, officers and employees and each other person who controls the Feeder Fund, as the case may be, within the meaning of Section 15 of the 1933 Act (each, a "Covered Person" and collectively, "Covered Persons"), against any and all losses, claims, demands, damages, liabilities and expenses (each, a "Liability" and collectively, the "Liabilities") (including the reasonable costs of investigating and defending against any claims therefor and any counsel fees incurred in connection therewith), joint or several, whether incurred directly by the Feeder Fund or through the Feeder Fund's Investment in the Master Portfolio, which

(i) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in the Master Portfolio's N-1A, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that the Master Portfolio will not be liable in any such case to the extent that any such Liability arises out of or is based upon any untrue statement or omission in or from the Master Portfolio's N-1A in reliance upon and in conformity with written information furnished to the Master Portfolio by the Feeder Fund specifically for use therein (for this purpose, information of any kind contained in any filing by the Feeder Fund with the Securities and Exchange Commission being deemed to have been so furnished to the Master Portfolio);

(ii) arise out of or are based upon a materially inaccurate calculation of the Master Portfolio's net asset value (whether by the Master Portfolio or any party retained for that purpose);

(iii) result from the failure of any representation or warranty made by the Master Portfolio to be accurate when made or the failure of the Master Portfolio to perform any covenant contained herein or to otherwise comply with the terms of this Agreement; or

(iv) arise out of any claim that the use of the names "Standard & Poor's," "S&P," "Standard & Poor's 500," "S&P 500" or 500" by the Master Portfolio violates any license or infringes upon any trademark;

provided, however, that in no case shall the Master Portfolio be liable with respect to any claim made against any such Covered Person unless such Covered Person shall have notified the Master Portfolio in writing of the nature of the claim within a reasonable time after the summons, other first legal process or formal or informal initiation of a regulatory investigation or proceeding shall have been served upon or provided to a Covered Person or any federal, state or local tax deficiency has come to the attention of the Feeder Fund or a Covered Person. Failure to notify the Master Portfolio of such claim shall not relieve it from any liability that it may have to any Covered Person otherwise than on account of the indemnification contained in this paragraph.

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(b) The Master Portfolio will be entitled to participate at its own expense in the defense or, if it so elects, to assume the defense of any suit brought to enforce any such liability, but, if the Master Portfolio elects to assume the defense, such defense shall be conducted by counsel chosen by the Master Portfolio. In the event that the Master Portfolio elects to assume the defense of any such suit and retain such counsel, each Covered Person and any other defendant or defendants may retain additional counsel, but shall bear the fees and expenses of such counsel unless (A) the Master Portfolio shall have specifically authorized the retaining of such counsel or (B) the parties to such suit include any Covered Person and the Master Portfolio, and any such Covered Person has been advised by counsel that one or more legal defenses may be available to it that may not be available to the Master Portfolio, in which case the Master Portfolio shall not be entitled to assume the defense of such suit notwithstanding its obligation to bear the fees and expenses of such counsel. The Master Portfolio shall not be liable to indemnify any Covered Person for any settlement of any claim affected without the Master Portfolio's written consent, which consent shall not be unreasonably withheld or delayed. The indemnities set forth in paragraph (a) will be in addition to any liability that the Master Portfolio might otherwise have to a Covered Person.

3.4 Allocation of Losses.

(a) If the indemnification provided for in Section 3.2 or Section 3.3 is for any reason unavailable to or insufficient to hold harmless a Covered Person in respect of any losses, claims, demands, damages, liabilities, or expenses referred to therein, then each indemnifying party shall contribute to the aggregate amount of such any losses, claims, demands, damages, liabilities, or expenses incurred by such Covered Person in such proportion as is appropriate to reflect the relative fault of the Feeder Fund and the Master Portfolio in connection with the statements or omissions or other action or failure to act which resulted in such losses, liabilities, claims, damages, or expenses, as well as any other relevant equitable considerations.

(b) In the case of any such untrue or alleged untrue statement of a material fact or omission or alleged omission to state a material fact, the relative fault of the Feeder Fund and the Master Portfolio shall be determined by reference to, among other things, whether any such untrue statement or alleged untrue statement or omission or alleged omission related to information supplied by the Feeder Fund or the Master Portfolio and the parties' relative intent, knowledge, access to information, and opportunity to correct or prevent such statement or omission.

(c) The Feeder Fund and the Master Portfolio agree that it would not be just and equitable if contribution pursuant to this Section 3.4 were determined by any method of allocation which does not take account of the equitable considerations referred to above in this Section 3.4. The aggregate amount of losses, claims, demands, damages, liabilities, and expenses incurred by a Covered Person and referred to above in this Section 3.4 shall be deemed to include any legal or other expenses reasonably incurred by such Covered Person in investigating, preparing, or defending against any litigation or any investigation or proceeding or any such claims and reasonable counsel fees incurred in connection therewith.

(d) For purposes of this Section 3.4, each person, if any, who controls the Feeder Fund or the Master Portfolio within the meaning of Section 15 of the 1933 Act or Section 20 of the Securities Exchange Act of 1934, as amended, shall have the same rights to contribution as the Feeder Fund or the Master Portfolio, as the case may be, and each director or trustee, officer, or employee of the Trust or the Company and each officer thereof who signed a registration statement shall have the same rights to contribution as the Feeder Fund or the Master Portfolio, as the case may be.

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IV
ADDITIONAL AGREEMENTS

4.1 Each party agrees that it shall hold in strict confidence all data and information obtained from the other party (unless such information is or becomes readily ascertainable from public or published information or trade sources) and shall ensure that its officers, employees and authorized representatives do not disclose such information to others without the prior written consent of the party from whom it was obtained, except if disclosure is required by the SEC, any other regulatory body or the Feeder Fund's or Master Portfolio's respective auditors, or in the opinion of counsel such disclosure is required by law, and then only with as much prior written notice to the other party as is practical under the circumstances.

4.2 No party shall issue any press release or otherwise make any public statements with respect to the matters covered by this Agreement without the prior consent of the other parties hereto, which consent shall not be unreasonably withheld; provided, however, that consent shall not be required if, in the opinion of counsel, such disclosure is required by law, provided further, however, that the party making such disclosure shall provide the other parties hereto with as much prior written notice of such disclosure as is practical under the circumstances.

V
TERMINATION, AMENDMENT AND WAIVER

5.1 Termination.

(a) This Agreement may be terminated by the Company upon five (5) business days notice to the Trust.

(b) This Agreement may be terminated at any time by the Company by withdrawing all of the Feeder Fund's Interest in the Master Portfolio.

(c) This Agreement may be terminated on not less than 120 days' prior written notice by the Trust to the Company.

(d) This Agreement may be terminated at any time immediately upon written notice to the other parties in the event that formal proceedings are instituted against another party to this Agreement by the SEC or any other regulatory body, provided that the terminating party has a reasonable belief that the institution of the proceeding is not without foundation and will have a material adverse impact on the terminating party.

(e) The indemnification obligations set forth in Article III and the confidentiality provisions in Section 4.1 shall survive the termination of this Agreement.

5.2 This Agreement may be amended, modified or supplemented at any time in such manner as may be mutually agreed upon in writing by the parties.

VI
GENERAL PROVISIONS

6.1 All notices and other communications given or made pursuant hereto shall to in writing and shall be deemed to have been duly given or made when actually received in person or by fax, or three

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days after being sent by certified or registered United States mail, return receipt requested, postage prepaid, addressed as follows:

If to the Feeder Fund:

State Street Master Funds
c/o State Street Bank and Trust Company
P.O. Box 5049
Boston, MA 02206
Attn: Julie Tedesco

If to the Master Portfolio:

State Street Master Funds
c/o State Street Bank and Trust Company
P.O. Box 5049
Boston, MA 02206
Attn: Julie Tedesco

Either party to this Agreement may change the identity of the person to receive notice by providing written notice thereof to all other parties to the Agreement.

6.2 Unless stated otherwise herein, all costs and expenses associated with this Agreement and the transactions contemplated hereby shall be paid by the party incurring such costs and expenses.

6.3 The headings and captions contained in this Agreement are for reference purposes only and shall not affect in any way the meaning or interpretation of this Agreement.

6.4 If any term or other provision of this Agreement is invalid, illegal or incapable of being enforced by any rule of law, or public policy, all other conditions and provisions of this Agreement shall nevertheless remain in full force and effect so long as the economic or legal substance of the transactions contemplated hereby is not affected in any manner adverse to any party. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto shall negotiate in good faith to modify this Agreement so as to effect the original intent of the parties as closely as possible in an acceptable manner to the end that the transactions contemplated hereby are fulfilled to the extent possible.

6.5 This Agreement and the agreements and other documents delivered pursuant hereto set forth the entire understanding between the parties concerning the subject matter of this Agreement and incorporate or supersede all prior negotiations and understandings. There are no covenants, promises, agreements, conditions or understandings, either oral or written, between them relating to the subject matter of this Agreement other than those set forth herein.

6.6 Each and all of the provisions of this Agreement shall be binding upon and inure to the benefit of the parties hereto and, except as otherwise specifically provided in this Agreement, their respective successors and assigns. Notwithstanding the foregoing, no party shall make any assignment of this Agreement or any rights or obligations hereunder without the written consent of all other parties.

6.7 This Agreement shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts without giving effect to the choice of law or conflicts of law provisions thereof.

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6.8 This Agreement may be executed in any number of counterparts, all of which shall constitute one and the same instrument, and any party hereto may execute this Agreement by signing one or more counterparts.

6.9 Nothing herein expressed or implied is intended or shall be construed to confer upon or give any person, other than the parties hereto and their successors or assigns, any rights or remedies under or by reason of this Agreement.

6.10 Any uncertainty or ambiguity existing herein shall not presumptively be interpreted against any party, but shall be interpreted according to the application of the rules of interpretation for arm's length agreements.

6.11 Each party expressly acknowledges the provision in the Articles of Incorporation of the Company and the Declaration of Trust of the Trust limiting the personal liability of shareholders and the officers and trustees of the Feeder Fund and the Master Portfolio, respectively.

6.12 The parties hereto agree and acknowledge that (a) the Company has entered into this Agreement solely on behalf of the Feeder Fund and that no other party shall have any obligation hereunder with respect to any liability of the Feeder Fund arising hereunder; (b) the Trust has entered into this Agreement solely on behalf of the Master Portfolio and that no other series of the Trust shall have any obligation hereunder with respect to any liability of the Master Portfolio arising hereunder; and (c) no series or feeder participant of the Master Portfolio shall be liable to any other series or feeder participant of the Master Portfolio.

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by their respective officers, thereunto duly authorized, as of the date first written above.

STATE STREET INSTITUTIONAL INVESTMENT
TRUST


By: Karen D. Gillogly Its: Treasurer

STATE STREET MASTER FUNDS


By: Donald A. Gignac Its: President

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EXHIBIT (J)

CONSENT OF ERNST & YOUNG LLP,
INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the references to our firm under the caption "Financial Highlights" in each Prospectus and "Counsel and Independent Registered Public Accounting Firm" in the Statement of Additional Information and to the use of our reports dated February 16, 2006, with respect to the financial statements of the State Street Equity 500 Index Fund, the State Street Equity 500 Index Portfolio, the State Street Institutional Liquid Reserves Fund and the State Street Money Market Portfolio included in their Annual Reports dated December 31, 2005 that are incorporated by reference into this Post-Effective Amendment Number 17 to the Registration Statement (Form N-1A No. 333-30810) of State Street Institutional Investment Trust.

/s/ ERNST & YOUNG LLP

Boston, Massachusetts
April 24, 2006


Exhibit (P)(2)

STATE STREET GLOBAL ADVISORS

SSGA FUNDS MANAGEMENT, INC.

CODE OF ETHICS

OCTOBER 2005

(SSGA(SM) LOGO)

STATE STREET GLOBAL ADVISORS
SSGA FUNDS MANAGEMENT, INC.


TABLE OF CONTENTS

I.    Introduction ........................................................    1

II.   Applicability .......................................................    1

III.  Key Definitions .....................................................    2

         Beneficial Ownership .............................................    2
         Covered Securities ...............................................    2

IV.   Pre-Clearance of Personal Securities Transactions ...................    3

V.    Restrictions ........................................................    4

         Blackout Periods .................................................    4
         Initial Public Offerings and Private Placements ..................    4
         Options ..........................................................    4
         Mutual Funds .....................................................    5
         Short-Term Trading and Other Restrictions ........................    5

VI.   Reporting Requirements ..............................................    5

VII.  Standard of Conduct .................................................    8

         Personal Trading .................................................    8
         Protecting Confidential Information ..............................    8
         Gifts and Entertainment ..........................................    9
         Service as a Director/Outside
         Employment and Activities ........................................   10

VIII. Sanctions ...........................................................   10

(SSGA(SM) LOGO)

STATE STREET GLOBAL ADVISORS
SSGA FUNDS MANAGEMENT, INC.


I. INTRODUCTION

The Code of Ethics (the "Code") is designed to reinforce State Street Global Advisors' ("SSgA's")/SSgA Funds Management, Inc.'s ("SSgA FM's") reputation for integrity by avoiding even the appearance of impropriety in the conduct of our business. The Code sets forth procedures and limitations which govern the personal securities transactions of every SSgA/SSgA FM employee.

SSgA/SSgA FM and our employees are subject to certain laws and regulations governing personal securities trading. We have developed this Code to promote the highest standards of behavior and ensure compliance with applicable laws. In addition to the provisions outlined in this document, employees in SSgA's Global Offices may be subject to different or additional requirements provided by their local Compliance Officer.

Employees should be aware that they may be held personally liable for any improper or illegal acts committed during their course of employment, and that "ignorance of the law" is not a defense. Employees may be subject to civil penalties such as fines, regulatory sanctions including suspensions, as well as criminal penalties.

Employees must read the Code and comply with it. Failure to comply with the provisions of the Code may result in serious sanctions including, but not limited to: disgorgement of profits, dismissal, substantial personal liability and referral to law enforcement agencies or other regulatory agencies. Employees should retain a copy of the Code in their records for future reference. Any questions regarding the Code should be directed to the Compliance and Risk Management Group or your local Compliance Officer.

General Principles

Each SSgA/SSgA FM employee is responsible for maintaining the very highest ethical standards when conducting business. More specifically, this means:

- Each employee has a duty at all times to place the interests of our clients first;

- All personal securities transactions must be conducted consistent with the Code and in such a manner as to avoid any actual or potential conflict of interest or other abuse of the employee's position of trust and responsibility; and

- No employee should take inappropriate advantage of his/her position or engage in any fraudulent or manipulative practice with respect to our clients' accounts.

II. APPLICABILITY

SSgA/SSgA FM Employees

This Code is applicable to all SSgA and SSgA FM employees. This includes full-time, part-time, benefited and non-benefited, and exempt and non-exempt employees. Additionally, each new employee's offer letter will include a copy of the Code of Ethics and a statement advising the individual that he/she will be subject to the Code of Ethics if he/she accepts the offer of employment. If, outside the U.S., due to local employment practices it is necessary to modify this approach then the offer letters will be revised in accordance with local law.

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Family Members and Related Parties

The Code applies to the accounts of the employee, his/her spouse or domestic partner, his/her minor children, his/her adult children living at home, and any relative, person or entity for whom the employee directs the investments. Joint accounts will also need to be included if an SSgA/SSgA FM employee is one of the joint account holders.

Contractors and Consultants

Each SSgA/SSgA FM contractor/consultant/temporary employee contract will include the Code as an addendum, and each contractor/consultant/temporary employee will be required to sign an acknowledgement that he/she has read the Code and will abide by it except for the pre-clearance and reporting provisions.

Investment Clubs

An employee who is a member of an investment club is subject to the pre-clearance and reporting requirements of the Code with respect to the transactions of the investment club. Additionally, memberships in Investment Clubs will require prior approval of the Compliance and Risk Management Group.

III. KEY DEFINITIONS

BENEFICIAL OWNERSHIP

For purposes of the Code, "Beneficial Ownership" shall be interpreted in the same manner as it would be in Rule 16a-1(a)(2) under the Securities Exchange Act of 1934 ("Exchange Act") in determining whether a person is subject to the provisions of Section 16 under the Exchange Act and the rules and regulations thereunder.

COVERED SECURITIES

For purposes of the Code, "Security" shall have the meaning set forth in Section 2(a)(36) of the Investment Company Act of 1940 ("1940 Act"). This definition of "Security" includes, but is not limited to: any note, stock, treasury stock, bond, debenture, evidence of indebtedness, certificates of interest or participation in any profit-sharing agreement, any put, call, straddle, option or privilege on any Security or on any group or index of Securities, or any put, call, straddle, option or privilege entered into on a national securities exchange relating to foreign currency. Further, for the purpose of the Code, "Security" shall include any commodity contracts as defined in Section 2(a)(1)(A) of the Commodity Exchange Act. This definition includes but is not limited to futures contracts on equity indices.

Covered securities will also include exchange traded funds ("ETFs") advised or sub-advised by SSgA/SSgA FM or any equivalents in local non-US jurisdictions, single stock futures and both the U.S. Securities and Exchange Commission ("SEC") and Commodity Futures Trading Commission ("CFTC") regulated futures.

"Security" shall NOT include direct obligations of the government of the United States or any other sovereign country or supra-national agency, bankers' acceptances, bank certificates of deposit, commercial paper and high quality short-term debt instruments, including repurchase agreements, variable and fixed insurance products, and interests in IRC Section 529 plans.

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IV. PRE-CLEARANCE OF PERSONAL SECURITIES TRANSACTIONS

Unless the investment type is exempted for pre-clearance purposes, all employees must request and receive pre-clearance prior to engaging in the purchase or sale of a security. Although a request may need to be pre-cleared, it may be subject to the de minimis exception which would permit a trade to be automatically pre-approved due to its size. All pre-clearance requests will be made by submitting a Pre-Trade Authorization Form ("PTAF") via the Code of Ethics Compliance system.

Pre-clearance approval is only good until midnight local time of the day when approval is obtained. "Good-till-cancelled" orders are not permitted. "Limit" orders must receive pre-clearance every day the order is open.

As there could be many reasons for pre-clearance being granted or denied, employees should not infer from the pre-clearance response anything regarding the security for which pre-clearance was requested.

De Minimis Exception

Employee transactions effected pursuant to the de minimis exception remain subject to the pre-clearance and reporting requirements of the Code. A "de minimis transaction" is a personal trade that meets the following conditions: A transaction of less than US $30,000 or the local country equivalent, 2,000 shares or units, and not more than 1% of the average daily trading volume in the security for the preceding 5 trading days.

Exempted Securities

Pre-clearance by employees is not required for the following transactions:

- Transactions made in an account where the employee pursuant to a valid legal instrument has given full investment discretion to an unaffiliated/unrelated third party;

- Purchases or sales of direct obligations of the government of the United States or other sovereign government or supra-national agency, high quality short-term debt instruments, bankers acceptances, certificates of deposit ("CDs"), commercial paper, repurchase agreements, and securities issued by open-end investment companies (e.g., mutual funds) not advised or sub-advised by SSgA/SSgA FM;

- Automatic investments in programs where the investment decisions are non-discretionary after the initial selections by the account owner (although the initial selection requires pre-clearance);

- Investments in dividend reinvestment plans;

- Purchases or sales of variable and fixed insurance products and IRC Section 529 plans;

- Exercised rights, warrants or tender offers;

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- General obligation municipal bonds, transactions in Employee Stock Ownership Programs ("ESOPs), and Share Builder and similar services; and

- Securities received via a gift or inheritance.

State Street Stock

Except as permitted in the following paragraph, any discretionary purchase or sale (including the exercising of options) of State Street stock, including shares in a 401(k) plan, needs to be pre-cleared subject to the de minimis requirements. This does not affect the current policy where an employee may trade State Street stock ("STT") or exercise options obtained pursuant to employee compensation plans on a specific day pursuant to State Street corporate policy.

Because STT stock may only be purchased on behalf of SSgA and SSgA FM clients following index investment objectives, employees may trade shares in STT or exercise options obtained pursuant to employee compensation plans above the de minimis requirements during certain trading windows established by STT (generally, from the third through the twelfth business day after the quarterly earnings release by the Corporation). Employees will be notified via e-mail when this period commences. During this period, all employees remain subject to the Insider Trading and Tipping rules in the Code of Ethics and Standard of Conduct.

V. RESTRICTIONS

BLACKOUT PERIODS

Subject to the de minimis exception, employees may not trade in a covered security on any day that a client account/fund has a pending buy or sell order in the same covered security.

In addition, subject to the de minimis exception, an employee may not buy or sell a security that a client account/fund has traded within 7 calendar days on either side of the fund's/ account's execution date.

INITIAL PUBLIC OFFERINGS AND PRIVATE PLACEMENTS

Employees are prohibited from acquiring securities through an allocation by the underwriter of an initial public offering ("IPO"). There is an exception for a situation where the spouse/domestic partner, with prior written disclosure to and written approval from a Senior Compliance Officer in the office where the staff member is principally employed, could acquire shares in an IPO of his/her employer.

In addition, employees are prohibited from purchasing securities in a private offering unless the purchase is approved in writing by a Senior Compliance Officer. Private placements include certain co-operative investments in real estate, commingled investment vehicles such as hedge funds, and investments in family owned businesses. Time-shares and cooperative investments in real estate used as a primary or secondary residence are not considered to be private placements.

OPTIONS

Employees are prohibited from buying or selling options. There is an exception for employees who have received options from a prior employer. In those instances, the exercising or selling of

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options received from the prior employer is subject to the pre-clearance and reporting requirements of this Code.

MUTUAL FUNDS

SSgA/SSgA FM employee investments in any mutual funds that are advised or sub-advised by SSgA FM or certain affiliates are subject to a ninety (90) calendar day holding period. These transactions are also subject to the pre-clearance and reporting requirements of this Code.

The current list of SSgA FM and certain affiliates'advised and sub-advised mutual funds is maintained by the Compliance and Risk Management Group and is located on the Code of Ethics Intranet page. Investments in money market funds or short-term income funds advised or sub-advised by SSgA FM are exempt from these requirements.

SHORT-TERM TRADING AND OTHER RESTRICTIONS

The following restrictions apply to all securities transactions by employees:

- Short-Term Trading. Employees are prohibited from the purchase and sale or sale and purchase of the same securities within sixty (60) calendar days. Mutual funds advised or sub-advised by SSgA FM or certain affiliates are subject to a ninety (90) day holding period.

- Excess Trading. While active personal trading may not in and of itself raise issues under applicable laws and regulations, we believe that a very high volume of personal trading can be time consuming and can increase the possibility of actual or apparent conflicts with portfolio transactions. Accordingly, an unusually high level of personal trading activity is strongly discouraged and may be monitored by the Compliance and Risk Management Group to the extent appropriate for the category of person, and a pattern of excessive trading may lead to the taking of appropriate action under the Code.

- Front Running. Employees may not engage in "front running," that is, the purchase or sale of securities for their own accounts on the basis of their knowledge of SSgA's/SSgA FM's trading positions or plans.

- Material Nonpublic Information. Employees possessing material nonpublic information regarding any issuer of securities must refrain from purchasing or selling securities of that issuer until the information becomes public or is no longer considered material.

- Shorting of Securities. Employees may not engage in the practice of shorting securities.

VI. REPORTING REQUIREMENTS

All Securities are subject to the reporting requirements of the Code except the following:

- Direct Obligations of any sovereign government or supra-national agency;

- Bankers' acceptances, bank certificates of deposit, commercial paper and high quality short-term debt instruments, including repurchase agreements;

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- Shares issued by open-end mutual funds and ETFs not advised or sub-advised by SSgA FM or certain affiliates;

- Investments in dividend reinvestment plans; and

- Variable and fixed insurance products and IRC Section 529 plans.

IRC 401(k) plans are also exempt from the reporting requirements except: (i) self-directed brokerage accounts and (ii) investments in State Street stock. Employees must report holdings of or transactions in ESOPs or pension or retirement plans if they have a direct or indirect Beneficial Ownership interest in any Covered Securities held by the plan.

Additionally, securities received via a gift or inheritance are required to be reported, but are not subject to the pre-clearance requirements of the Code.

a. Initial Holdings Reports

Within ten (10) calendar days of being hired by SSgA/SSgA FM, each employee must provide the Compliance and Risk Management Group with a statement of all securities holdings and brokerage accounts. More specifically, each employee must provide the following information:

- The title, number of shares and principal amount of each Security in which the employee had any direct or indirect Beneficial Ownership when the person became an employee;

- The name of any broker, dealer or bank with whom the employee maintained an account in which any securities were held for the direct or indirect benefit of the employee as of the date the person became an employee; and

- The date the report is submitted by the employee.

b. Duplicate Statements and Confirmations

Upon SSgA/SSgA FM employment and for any accounts opened during employment, an employee must instruct his/her broker-dealer, trust account manager or other entity through which he/she has a securities trading account to send directly to our Compliance and Risk Management Group:

- Trade confirmation summarizing each transaction; and

- Periodic statements.

This applies to all accounts in which an employee has direct or indirect Beneficial Ownership. A sample letter with the Compliance address is located on the Code of Ethics Intranet page.

c. Quarterly Transaction Reports

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Each employee is required to submit quarterly his/her Quarterly Securities Report within ten (10) calendar days of each calendar quarter end to the Compliance and Risk Management Group. The form for making this report will be provided to each employee on a quarterly basis.

Specific information to be provided includes:

1. With respect to any transaction during the quarter in a Security in which any employee had any direct or indirect Beneficial Ownership:

- The date of the transaction, the title, the interest rate and maturity date (if applicable), the number of shares and the principal amount of each Security involved;

- The nature of the transaction, (i.e., purchase, sale, or other type of acquisition or disposition);

- The price of the Security at which the transaction was effected;

- The name of the broker, dealer or bank with or through which transaction was effected; and

- The date that the report is submitted by the employee.

2. With respect to any account established by the employee in which any securities were held during the quarter for the direct or indirect benefit of the employee:

- The name of the broker, dealer, or bank with whom the employee established the account;

- The date the account was established; and

- The date the report is submitted by the employee.

d. Annual Holdings Reports

Each employee is required to submit annually (i.e., once each and every calendar year) a list of holdings, which is current as of a date no more than thirty (30) days before the report is submitted. In addition, each employee is required to certify annually that he/she has reviewed and understands the provisions of the Code. The forms for making these reports will be provided to each employee on an annual basis.

Specific information to be provided includes:

- The title, number of shares and principal amount of each Covered Security in which the employee had any direct or indirect beneficial ownership;

- The name of any broker, dealer or bank with whom the employee maintains an account in which any securities are held for the direct or indirect benefit of the employee; and

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- The date that the report is submitted by the employee.

VII. STANDARD OF CONDUCT

PERSONAL TRADING

All State Street employees, including SSgA/SSgA FM employees, are required to follow the provisions outlined in State Street Corporation's Corporate Standard of Conduct. The Standard of Conduct includes a policy on Personal Trading which all State Street employees must follow in addition to any additional personal trading policies implemented by their business areas. The policy includes the following list of provisions:

- Employees will not buy or sell securities (or recommend their purchase or sale) based upon "inside information."

- Employees will not sell State Street securities short.

- Employees will not engage in options trading or hedging transactions in State Street securities.

- Employees will not sell the securities of a customer short when we, as individual employees, are directly responsible for providing services to that customer.

- Employees will not buy options in the securities of a customer (unless conducted as part of a hedging strategy) when we, as individual employees, are directly responsible for providing services to that customer.

- Employees will not purchase securities of an issuer when State Street is involved in the underwriting or distribution of the securities.

- Employees will not buy or sell securities based upon our knowledge of the trading position or plans of State Street or a customer.

- Employees will not buy or sell securities based upon anticipated research recommendations. (Employees are required to wait at least 3 business days following public dissemination of a recommendation made by State Street prior to making a personal trade. Some business units may impose a longer restriction period.)

- Employees will not use their influence as State Street employees to accept preferential treatment from an issuer or broker with respect to an investment opportunity, nor from a broker with respect to the fees charged in relation to conducting a personal securities transaction.

- Employees will not originate a rumor nor participate in the circulation of one concerning any publicly traded security, particularly the securities of State Street or any customer of State Street.

- Employees allow trading of customer accounts and for State Street's own account to precede personal trades if the personal trades could affect the market price of a security.

- Employees will not invest in the securities of a supplier or vendor to State Street, if they as individual employees, have substantial responsibility for representing State Street in its relationship with that firm.

PROTECTING CONFIDENTIAL INFORMATION

Employees may receive information about SSgA/SSgA FM, State Street Bank & Trust Company, State Street Corporation, their clients and other parties that, for various reasons, should be treated as confidential. All employees are expected to strictly comply with measures necessary to preserve the confidentiality of the information.

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Insider Trading and Tipping

The misuse of material nonpublic information, or inside information, constitutes a fraud under the securities laws of the United States and many other countries. Fraudulent misuse of inside information includes buying or selling securities while in possession of material nonpublic information for an employee or employee-related account, a proprietary account or for the account of any client. Fraudulent misuse of inside information also includes disclosing or tipping such information to someone else who then trades on it, or using such information as a basis for recommending the purchase or sale of a security. Information is material when it has market significance and there is a likelihood that a reasonable investor would consider the information important in deciding whether to buy or sell the securities of the company involved. It is nonpublic if it has not been broadly disseminated.

In no event, may any employee who receives inside information use that information to trade or recommend securities affected by such information for personal benefit, the benefit of SSgA/SSgA FM or any affiliate or the benefit of a third party. More specifically:

- No employee may, while in possession of inside information affecting a security, purchase or sell such security for the account of such employee, a client or any other person or entity.

- No employee may disclose inside information to any person outside of SSgA/SSgA FM. However, discussions with legal counsel and disclosures authorized by the client in furtherance of a related project or transaction are permitted.

- No employee may recommend or direct the purchase from or sale of a security to anyone while in the possession of inside information, however obtained.

GIFTS AND ENTERTAINMENT

All employees are required to follow the Corporate Standard of Conduct's Gifts and Entertainment Policy. The policy includes the following provisions:

- Employees should avoid any excessive or disreputable entertainment that would reflect unfavorably on State Street;

- Employees do not offer or accept cash or its equivalent as a gift;

- Employees recognize that promotional gifts such as those that bear the logo of a company's name or that routinely are made available to the general public are generally acceptable business gifts;

- Employees fully, fairly and accurately account on the books and records of State Street for any expense associated with a gift or entertainment; and

- Employees do not accept any gift or bequest under a will or trust from a customer of State Street.

For purposes of the SSgA/SSgA FM Code, the gifts and entertainment limit will be $250.00 or the local equivalent. In order for an employee to accept a gift above the limit, he/she must obtain prior written approval from his/her manager and provide a copy of the approval to the Chief Compliance Officer.

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SERVICE AS A DIRECTOR/OUTSIDE EMPLOYMENT AND ACTIVITIES

All employees are required to comply with the Corporate Standard of Conduct's Conflicts from Outside Activities Policy. The policy includes the following provisions:

- Employees are to avoid any business activity, outside employment or professional service that competes with State Street or conflicts with the interests of State Street or its customers.

- An employee is required to obtain the approval of his/her Area Executive before becoming a director, officer, employee, partner or sole proprietor of a "for profit" organization. The request for approval should disclose the name of the organization, the nature of the business, whether any conflicts of interest could reasonably result from the association, whether fees, income or other compensation will be earned and whether there are any relationships between the organization and State Street. The request for approval along with the preliminary approval of the Area Executive is subject to the final review and approval of the State Street General Counsel and the Chief Executive Officer.

- Employees do not accept any personal fiduciary appointments such as administrator, executor or trustee other than those arising from family or other close personal relationships.

- Employees do not use State Street resources, including computers, software, proprietary information, letterhead and other property in connection with any employment or other activity outside State Street.

- Employees disclose to their Area Executive any situation that could present a conflict of interest or the appearance of a conflict with State Street and discuss how to control the risk.

When completing their annual certification acknowledging receipt and understanding of the Code of Ethics, SSgA/SSgA FM employees will be asked to disclose all outside affiliations. Any director/trustee positions with public companies or companies likely to become public are prohibited without prior written approval from the employees' Area Executive.

VIII. SANCTIONS

Upon discovering a violation of this Code by an employee or his/her family member or related party, the Code of Ethics Review Committee may impose such sanctions as it deems appropriate, including, among other things, the following:

- A letter of censure to the violator;

- A monetary fine levied on the violator;

- Suspension of the employment of the violator;

- Termination of the employment of the violator;

- Civil referral to the SEC or other civil regulatory authorities determined by SSgA/SSgA FM; or

- Criminal referral - determined by SSgA/SSgA FM.

Examples of possible sanctions include, but are not limited to:

- A warning letter, with a cc: to the employee's manager, for a first time pre-clearance or reporting violation;

- Monetary fines and disgorgement of profits when an employee profits on the purchase of a security he/she should not purchase; and

- Recommendation for suspension or termination if an employee is a serial violator of the Code.

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Appeals Process

If an employee decides to appeal a sanction, he/she should contact Human Resources.

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EXHIBIT (P)(3)

ALPS DISTRIBUTORS, INC.
(THE "COMPANY" OR "UNDERWRITER")

CODE OF ETHICS

I. Purpose of the Code of Ethics

This code is based on the principle that, you as an access person of the Company, will conduct your personal investment activities in accordance with:

- the duty at all times to place the interests of each Investment Company's shareholders first;

- the requirement that all personal securities transactions be conducted consistent with this Code of Ethics and in such a manner as to avoid any actual or potential conflict of interest or any abuse of an individual's position of trust and responsibility; and

- the fundamental standard that Company personnel should not take inappropriate advantage of their positions.

In view of the foregoing, the Company has adopted this Code of Ethics (the "Code") to specify a code of conduct for certain types of personal securities transactions which may involve conflicts of interest or an appearance of impropriety and to establish reporting requirements and enforcement procedures.

II. Legal Requirement

Pursuant to Rule 17j-1(b) of the Investment Company Act of 1940 (the "Act"), it is unlawful for the Company, or any Affiliated Person to:

- employ any device, scheme or artifice to defraud the Investment Company;

- make any untrue statement of a material fact or fail to state a material fact necessary in order to make the statements made, in light of the circumstances under which they were made, not misleading to the Investment Company;

- engage in any act, practice, or course of business which operates or would operate as a fraud or deceit upon the Investment Company; or

- engage in any manipulative practice with respect to any investment portfolios in the Trust of the Investment Company,

in connection with the purchase or sale (directly or indirectly) the Company, or Affiliated Person,


of a security "held or to be acquired" by an Investment Company.

III. Definitions - All definitions shall have the same meaning as explained in
Section 2(a) of the Act and are summarized below.

ACCESS PERSON means any director, officer or general partner of the principal underwriter who, if also serving as an officer of a Fund for which ADI is also principal underwriter, makes, participates in or obtains information regarding, the purchase or sale of Covered Securities by a Fund for which the principal underwriter acts, or whose functions or duties in the ordinary course of business relate to the making of any recommendation to a Fund regarding the purchase or sale of Covered Securities.

AUTOMATIC INVESTMENT PLAN means a program in which regular periodic purchases (or withdrawals) are made automatically in (or from) investment accounts in accordance with a predetermined schedule and allocation. An Automatic Investment Plan includes a dividend reinvestment plan.

BENEFICIAL OWNERSHIP shall have the same meaning as that set forth in Rule 16a-1(a)(2) of the Securities Exchange Act of 1934.

CONTROL shall have the same meaning as that set forth in Section 2(a)(9) of the Act.

COVERED SECURITY - shall have the meaning set forth in Section 2(a)(36) of the Act except that it does not include an exempt security.

EXEMPT SECURITY - shall include securities issued by the United States Government, short-term debt securities which are "government securities" within the meaning of Section 2(a)(16) of the Act, bankers' acceptances, bank certificates of deposit or commercial paper, shares of registered open-end investment companies (other than open-end exchange traded funds), and high quality short-term debt instruments, including repurchase agreements.

EXCHANGE TRADED FUND - an open-end registered investment company that is not a unit investment trust, and that operates pursuant to an order from the SEC exempting it from certain provisions of the Investment Company Act permitting it to issue securities that trade on the secondary market. Examples of open-end exchange-traded funds include, but are not limited to: SPDRS; iShares; PowerShares; etc.

INVESTMENT COMPANY - A company registered as such under the Investment Company Act of 1940 and for which the Underwriter is the principal underwriter.

INVESTMENT PERSONNEL - (a) employees of the Investment Company, its investment adviser, and/or the Underwriter who participate in making investment recommendations to the Investment Company; and (b) persons in a control relationship with the Investment Company or adviser who obtain information about investment recommendations made to the Investment Company.


SECURITY BEING CONSIDERED FOR PURCHASE OR SALE - when a recommendation to purchase or sell a security has been made or communicated and, with respect to the person making the recommendation, when such person seriously considers making such a recommendation.

SECURITY HELD OR TO BE ACQUIRED means: (1) any Covered Security which, within the most recent 15 days: (a) is or has been held by the Investment Company; or
(b) is being or has been considered by the Investment Company or its investment advisor for purchase by the Investment Company; and (2) any option to purchase or sell, and any security convertible into or exchangeable for, a Covered Security that is held or to be acquired by the Investment Company.

UNDERWRITER - means ALPS Distributors, Inc.

IV. Policies of the Company Regarding Personal Securities Transactions

General

No Access Person of the Company shall engage in any act, practice or course of business that would violate the provisions of Rule 17j-1 as set forth above, or in connection with any personal investment activity, engage in conduct inconsistent with this Code.

Specific Policies

No Access Person shall purchase or sell, directly or indirectly, any security in which he/she has, or by reason of such transaction acquires, any direct or indirect beneficial ownership and which he/she knows or should have known at the time of such purchase or sale:

- is being considered for purchase or sale by an Investment Company; or

- is being purchased or sold by an Investment Company.

Pre-approval of Investments in IPOs and Limited Offerings

Investment Personnel must obtain approval from the Investment Company or the Investment Company's investment adviser before directly or indirectly acquiring beneficial ownership in any securities in an initial public offering or in a private placement or other limited offering.

V. Reporting Procedures

The Compliance Officer of the Company shall notify each person (annually in January of each year), considered to be an Access Person of the Company that he/she is subject to the reporting requirements detailed in Sections (a), (b) and (c) below and shall deliver a copy of this Code to such Access Person.

In order to provide the Company with information to enable it to determine with


reasonable assurance whether the provisions of this Code are being observed, every Access Person of the Company must report to the Company the following:

a) Initial Holdings Reports. Every Access Person must report on the Holdings Report, attached hereto, no later than 10 days after becoming an Access Person, the following information:

- The title, number of shares and principal amount of each Covered Security in which the Access Person had any direct or indirect beneficial ownership when the person became an Access Person;

- The name of any broker, dealer or bank with whom the Access Person maintained an account in which any securities were held for the direct or indirect benefit of the Access Person as of the date the person became an Access Person; and

- The date that the report is submitted by the Access Person.

This information must be current as of a date no more than 45 days prior to the date the person becomes an access person.

b) Quarterly Transaction Reports. Every Access Person must report on the Transaction Report, attached hereto, no later than 30 days after the end of a calendar quarter, the following information with respect to any transaction during the quarter in a Covered Security in which the Access Person had any direct or indirect beneficial ownership:

- The date of the transaction, the title, the interest rate and maturity date (if applicable),the number of shares, and the principal amount of each Covered Security involved;

- The nature of the transaction (i.e., purchase, sale or any other type of acquisition or disposition);

- The price of the Covered Security at which the transaction was effected;

- The name of the broker, dealer or bank with or through whom the transaction was effected; and

- The date that the report is submitted by the Access Person.

Furthermore, an Access Person need not make a quarterly transaction report under section V.b. of this Code of Ethics with respect to transactions effected pursuant to an Automatic Investment Plan.

With respect to any account established by the Access Person in which ANY SECURITIES were held during the quarter for the direct or indirect benefit of the Access Person, each Access


Person must report to the Compliance Officer of the Company, no later than 30 days after the end of a calendar quarter the following information:

- The name of the broker, dealer or bank with whom the Access Person established the account;

- The date the account was established; and

- The date that the report is submitted by the Access Person.

c) Annual Holdings Reports. Every Access Person must report on the Holdings Report, attached hereto, annually, the following information (which information must be current as of a date no more than 45 days before the report is submitted):

- The title, number of shares and principal amount of each Covered Security in which the Access Person had any direct or indirect beneficial ownership;

- The name of any broker, dealer or bank with whom the Access Person maintains an account in which any securities are held for the direct or indirect benefit of the Access Person; and

- The date that the report is submitted by the Access Person.

VI. Review of Reports

The Compliance Officer of the Company shall be responsible for reviewing the reports received, maintaining a record of the names of the persons responsible for reviewing these reports, and as appropriate, comparing the reports with this Code, and reporting to the Company's senior management:

- any transaction that appears to evidence a possible violation of this Code; and

- apparent violations of the reporting requirements stated herein.

Senior management shall review the reports made to them hereunder and shall determine whether the policies established in Sections IV and V of this Code have been violated, and what sanctions, if any, should be imposed on the violator. Sanctions include but are not limited to a letter of censure, suspension or termination of the employment of the violator or termination of the violator's license with the Underwriter, or the unwinding of the transaction and the disgorgement of any profits.

Senior management and the board of directors of the Company shall review the operation of this Code at least annually. All material violations of this Code and any sanctions imposed with respect thereto shall periodically be reported to the board of trustees of the Investment Company with respect to the securities being considered for purchase or sale by, or held or to be


acquired by, that Investment Company.

VII. Certification

Each Access Person will be required to certify annually that he/she has read and understood the provisions of this Code and will abide by it. Each Access Person will further certify that he/she has disclosed or reported all personal securities transactions required to be reported under the Code. A form of such certification is attached hereto.

Before the Board of Trustees of an Investment Company may approve the code of ethics, the Company must certify to the Board that it has adopted procedures reasonably necessary to prevent Access Persons from violating its Code of Ethics. Such certification shall be submitted to the Board of Trustees at least annually.


Sources:

Section 17j-1 (as amended) of the Investment Company Act of 1940 (the "Act");

Section 16 (as amended) of the Securities Exchange Act of 1934 (the "Exchange Act");

The "Report of the Advisory Group on Personal Investing" issued by the Investment Company Institute on May 9, 1994; and,

The Securities and Exchange Commission's September 1994 Report on "Personal Investment Activities of Investment Company Personnel."

dated:   May, 1994
revised: December 31, 2004
revised: February 3, 2006 (effective March 31, 2006)