Investment Adviser

Loomis, Sayles & Company, L.P.

Portfolio Managers

Fan Hu, CFA, vice president of the Adviser, has served as portfolio manager of the Fund since April 2006.

Clifton V. Rowe, CFA, vice president of the Adviser, has served as portfolio manager of the Fund since March 2006.

For important information about the purchase and sale of fund shares, tax information, and financial intermediary compensation, please turn to the “Additional Information” section on page [      ] of the Statutory Prospectus.

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additional information

PURCHASE AND SALE OF FUND SHARES

The following chart shows the investment minimum for each Fund:

Each Fund reserves the right to create investment minimums at its sole discretion.

Shares of each Fund are offered exclusively to investors in “wrap fee” programs approved by Natixis Advisors and/or Loomis Sayles and to institutional advisory clients of Loomis Sayles or Natixis Advisors that, in each case, meet the Fund’s policies as established by Loomis Sayles.

Shares normally can be redeemed only through the shareholder’s wrap program sponsor for shareholders owning shares through wrap accounts or by contacting Loomis Sayles, Natixis Advisors or Boston Financial Data Services, Inc., the Fund’s transfer agent (the “Transfer Agent”).

TAX INFORMATION

Distributions of investment income may be taxable to you as ordinary income. Distributions of capital gains may be taxable as either long-term capital gain or ordinary income depending on how long the Fund owned the investments that generated the gains. Fund distributions are taxable whether you receive them in cash or in additional shares. Distributions by the Fund to retirement plans and other investors that qualify for tax-exempt treatment under U.S. federal income tax law generally will not be taxable.

PAYMENTS TO BROKER-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of the Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

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more information about investment strategies

Loomis Sayles High Income Opportunities Fund

Investment Objective The Fund’s investment objective may be changed without shareholder approval.

Principal Investment Strategies Under normal market conditions, the Fund will invest substantially all of its assets, and may invest up to 100% of its assets, in High-Income Securities. High-Income Securities are fixed-income securities that Loomis Sayles believes have the potential to generate relatively high levels of current income. High-Income Securities may include debt securities that are rated below investment-grade quality at the time of investment ( i.e. , none of the three major ratings agencies (Moody’s, Fitch or S&P) have rated the securities in one of their respective top four ratings categories) or, if unrated, are determined to be of comparable quality by Loomis Sayles. These high-yield debt securities are commonly called “junk bonds.” High-Income Securities may also include investment-grade fixed-income securities. High-Income Securities may be convertible into, or exchangeable for, equity securities or they may carry with them the right to acquire equity securities evidenced by warrants attached to the debt security or acquired as part of a unit with the debt security. The High-Income Securities in which the Fund invests may have fixed or variable principal payments and all types of interest rate and dividend and reset terms, including fixed rate, adjustable rate, zero-coupon, contingent, deferred, pay-in-kind and auction rate.

Loomis Sayles Securitized Asset Fund

Investment Objective The Fund’s investment objective may be changed without shareholder approval.

Principal Investment Strategies Loomis Sayles seeks to achieve the Fund’s objective by, under normal market conditions, investing at least 80% of the Fund’s net assets (plus any borrowings made for investment purposes) in a diversified portfolio of securitized assets, such as mortgage-backed and other asset-backed securities. In accordance with applicable Securities and Exchange Commission (“SEC”) requirements, the Fund will notify shareholders prior to any change to such policy taking effect.

Frequent Trading The Fund may also engage in active and frequent trading of securities. Frequent trading may produce a high level of taxable gains, which may lower the Fund’s return.

TEMPORARY DEFENSIVE MEASURES

Each Fund may hold any portion of its assets in cash (U.S. Dollars, foreign currencies or multinational currency units) and/or invest in money market instruments or high-quality debt securities as Loomis Sayles deems appropriate. A Fund may miss certain investment opportunities if it uses defensive strategies and thus may not achieve its investment objective.

REPURCHASE AGREEMENTS

Under a repurchase agreement, a Fund purchases a security and obtains a simultaneous commitment from the seller (a bank or, to the extent permitted by the Investment Company Act of 1940, as amended, (the “1940 Act”), a recognized securities dealer) to repurchase the security at an agreed-upon price and date (usually seven days or less from the date of original purchase). The resale price is in excess of the purchase price and reflects an agreed-upon market rate of interest unrelated to the coupon rate on the purchased security. Such transactions afford the Fund the opportunity to earn a return on its cash at what is expected to be minimal market risk. The Fund may invest in a repurchase agreement that does not produce a positive return to the Fund if the Adviser believes it is appropriate to do so under the circumstances (for example, to help protect the Fund’s uninvested cash against the risk of loss during periods of market turmoil). There is a risk that the seller may fail to repurchase the underlying security. In such event, the Fund would attempt to exercise rights with respect to the underlying security, including possible disposition in the market. However, the Fund may be subject to various delays and risks of loss, including possible declines in the value of the underlying security, possible reduced levels of income, inability to enforce rights and expenses involved in attempted enforcement. Repurchase agreements maturing in more than seven days may be considered illiquid securities.

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SECURITIES LENDING

Each Fund may lend a portion of its portfolio securities to brokers, dealers and other financial institutions, provided that a number of conditions are satisfied, including that the loan is fully collateralized. Please see the section “Investment Strategies” in the Statement of Additional Information (“SAI”) for details. When a Fund lends portfolio securities, its investment performance will continue to reflect changes in the value of the securities loaned, and the Fund will also receive a fee or interest on the collateral. Securities lending involves the risk of loss of rights in the collateral or delay in recovery of the collateral if the borrower fails to return the security loaned or becomes insolvent. In addition, any investment of cash collateral is generally at the sole risk of the Fund. Any income or gains and losses from investing and reinvesting any cash collateral delivered by a borrower pursuant to a loan are generally at the Fund’s risk, and to the extent any such losses reduce the amount of cash below the amount required to be returned to the borrower upon the termination of any loan, the Fund may be required by the securities lending agent to pay or cause to be paid to such borrower an amount equal to such shortfall in cash, possibly requiring it to liquidate other portfolio securities to satisfy its obligations. A Fund may pay lending fees to the party arranging the loan.

STRUCTURED NOTES

The Funds may invest in structured notes, which are derivative debt instruments with principal and/or interest payments linked to the value of a commodity, a foreign currency, an index of securities, an interest rate or other financial indicators (“reference instruments”). The payments on a structured note may vary based on changes in one or more specified reference instruments, such as a floating interest rate compared to a fixed interest rate, the exchange rates between two currencies, one or more securities or a securities or commodities index. A structured note may be positively or negatively indexed. For example, its principal amount and/or interest rate may increase or decrease if the value of the reference instrument increases, depending upon the terms of the instrument. The change in the principal amount payable with respect to, or the interest rate of, a structured note may be a multiple of the percentage change (positive or negative) in the value of the underlying reference instrument or instruments. Structured notes can be used to increase a Fund’s exposure to changes in the value of assets or to hedge the risks of other investments that a Fund holds.

TRANSACTIONS WITH OTHER INVESTMENT COMPANIES

Pursuant to SEC exemptive relief, each Fund may be permitted to invest its daily cash balances in shares of money market and short-term bond funds advised by Natixis Advisors (an affiliate of Loomis Sayles) or its affiliates (the “Central Funds”). The Central Funds currently include two money market funds: Natixis Cash Management Trust-Money Market Series (the “Money Market Fund”) and Institutional Daily Income Fund (the “Daily Income Fund”). The Money Market Fund is advised by Natixis Advisors and subadvised by Reich & Tang Asset Management, LLC (“Reich & Tang”) and the Daily Income Fund is advised by Reich & Tang. Because Loomis Sayles, Natixis Advisors and Reich & Tang are each subsidiaries of Natixis Global Asset Management, L.P. (“Natixis US”), the Funds and the Central Funds may be considered to be related companies comprising a “group of investment companies” under the 1940 Act.

Pursuant to such exemptive relief, the Funds may also borrow and lend money for temporary or emergency purposes directly to and from other Funds through an interfund credit facility. In addition to the Funds and the Central Funds, series of the following mutual fund groups may also be able to participate in the facility: Natixis Funds Trust I (except the CGM Advisor Targeted Equity Fund series), Natixis Funds Trust II, Natixis Funds Trust III, Natixis Funds Trust IV, Harris Associates Investment Trust, Loomis Sayles Funds I, Loomis Sayles Funds II and Gateway Trust. The advisers and subadvisers to these mutual funds currently include Natixis Advisors, Reich & Tang, Loomis Sayles, AEW Capital Management, L.P., AlphaSimplex Group, LLC, BlackRock Investment Management, LLC (“BlackRock”), Gateway Investment Advisers, LLC, Hansberger Global Investors, Inc., Harris Associates L.P. and Vaughan Nelson Investment Management, L.P. Each of these advisers and subadvisers (except for BlackRock) are subsidiaries of Natixis US and are thus “affiliated persons” under the 1940 Act by reason of being under common control by Natixis US. In addition, because the Funds, and other funds, are advised by firms that are affiliated with one another, they may be considered to be related companies comprising a “group of investment companies” under the 1940 Act. The Central Funds will participate in the credit facility only as lenders. Participation in such an interfund lending program would be voluntary for both borrowing and lending funds, and a Fund would participate in an interfund lending program only if the Fund’s Board of Trustees determined that doing so would benefit a Fund. Should a Fund participate in such an interfund lending program, the Fund’s Board of Trustees would establish procedures for the operation of the program by the advisers or an affiliate. The Funds may engage in the transactions described above without further notice to shareholders. The Funds may also make investments in related investment companies to the extent permitted by SEC regulations.

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PERCENTAGE INVESTMENT LIMITATIONS

Except as set forth in the SAI, the percentage limitations set forth in this Prospectus and the SAI apply at the time an investment is made and shall not be considered violated unless an excess or deficiency occurs or exists immediately after and as a result of such investment.

PORTFOLIO HOLDINGS

A description of the Funds’ policies and procedures with respect to the disclosure of each Fund’s portfolio securities is available in the Funds’ SAI.

A “snapshot” of each Fund’s investments may be found in each Fund’s annual and semiannual reports. In addition, a list of each Fund’s full portfolio holdings, which is updated monthly after an aging period of at least 30 days, is available on the Funds’ website at www.loomissayles.com (click on “Investor Type,” “Individual Investors” and then “Holdings”). These holdings will remain accessible on the website until each Fund files its Form N-CSR or Form N-Q with the SEC for the period that includes the date of the information. Please see the back cover of this Prospectus for more information on obtaining a copy of a Fund’s current annual or semiannual report.

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additional information regarding principal & related risks

This section provides more information on the principal risks that may affect a Fund’s portfolio, in addition to those described in the Fund Summary. In seeking to achieve their investment goals, the Funds may also invest in various types of securities and engage in various investment practices which are not a principal focus of the Funds and therefore are not described in this Prospectus. These securities and investment practices and their associated risks are discussed in the Funds’ SAI, which is available without charge upon request (see back cover).

CREDIT RISK

This is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to an over-the-counter transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Each Fund may be subject to credit risk to the extent that it invests in fixed-income securities or is a party to over-the-counter transactions.

A Fund that invests in lower-rated fixed-income securities (“junk bonds”) is subject to greater credit risk and market risk than a fund that invests in higher-quality fixed-income securities. Lower-rated fixed-income securities are considered predominantly speculative with respect to the ability of the issuer to make timely principal and interest payments.

A Fund that invests in fixed-income securities issued in connection with corporate restructurings by highly-leveraged issuers or in fixed-income securities that are not current in the payment of interest or principal ( i.e. , in default) will be subject to greater credit risk.

A Fund that invests in non-U.S. securities is subject to increased credit risk, for example, because of the difficulties of requiring non-U.S. entities to honor their contractual commitments and because financial reporting and other standards are often less robust in foreign countries.

CURRENCY RISK

This is the risk that fluctuations in exchange rates between the U.S. dollar and non-U.S. currencies may cause the value of a Fund’s investments to decline. A Fund that may invest in securities denominated in, or receive revenues in, non-U.S. currency is subject to currency risk.

DERIVATIVES RISK

Each Fund may use derivatives, which are financial contracts whose value depends upon or is derived from the value of an underlying asset, reference rate or index. Examples of derivatives include options, futures and swap transactions (including credit default swaps), foreign transactions and foreign currency transactions. The Funds may (but are not required to) use derivatives as part of a strategy designed to reduce exposure to other risks, such as risks associated with changes in interest rates or currency risk (“hedging”). When a derivative security (a security whose value is based on another security, currency, index or other instrument) is used as a hedge against an offsetting position that a Fund also holds, any loss generated by the derivative security should be substantially offset by a gain on the hedged instrument, and vice versa. To the extent that a Fund uses a derivative security for purposes other than as a hedge, or if a Fund hedges imperfectly, a Fund is directly exposed to the risks of that derivative security and any loss generated by the derivative security will not be offset by a gain. The Funds may also use derivatives for leverage, which increases opportunities for gain but also involves greater risk of loss due to leveraging risk, and to earn income, enhance yield or broaden the Fund’s diversification by gaining exposure to issuers, indices, sectors, currencies and/or geographic regions. The use of derivatives for these purposes entails greater risk than using derivatives solely for hedging purposes.

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Funds that use derivatives also face additional risks, such as liquidity risk, market risk, management risk, the credit risk relating to the other party to a derivative contract, the risk of difficulties in pricing and valuation, the risk of ambiguous documentation and the risk that changes in the value of a derivative may not correlate perfectly with relevant assets, rates or indices. This could, for example, cause a derivative transaction to imperfectly hedge the risk which it was intended to hedge. A Fund’s use of derivative instruments may involve risks greater than the risks associated with investing directly in securities and other traditional investments, may cause the Fund to lose more than the principal amount invested and may subject a Fund to the potential for unlimited loss. A Fund may be required to sell other securities at inopportune times to meet collateral requirements on its derivatives transactions. In addition, a Fund’s use of derivatives may increase or accelerate the amount of taxes payable by shareholders. Also, suitable derivative transactions may not be available in all circumstances and there can be no assurance that a Fund will engage in these transactions to reduce exposure to other risks when that would be beneficial or that, if used, such strategies will be successful.

Recently, several broker-dealers and other financial institutions have experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. Although the Adviser monitors the creditworthiness of the Fund’s derivative counterparties, there can be no assurance that the Fund’s counterparties will not experience similar difficulties, possibly resulting in losses to the Fund. Losses resulting from the use of derivatives will reduce the Fund’s net asset value (“NAV”), and possibly income, and the losses may be significantly greater than if derivatives had not been used.

EMERGING MARKETS RISK

Economic and Political Risks. Emerging market countries often experience instability in their political and economic structures. Government actions could have a significant impact on the economic conditions in such countries, which in turn would affect the value and liquidity of the assets of a Fund invested in emerging market securities. Specific risks that could decrease a Fund’s return include seizure of a company’s assets, restrictions imposed on payments as a result of blockages on foreign currency exchanges and unanticipated social or political occurrences.

The ability of the government of an emerging market country to make timely payments on its debt obligations will depend on many factors, including the extent of its reserves, fluctuations in interest rates and access to international credit and investments. A country that has non-diversified exports or relies on certain key imports will be subject to greater fluctuations in the pricing of those commodities. Failure to generate sufficient earnings from foreign trade will make it difficult for an emerging market country to service its foreign debt.

Companies trading in developing securities markets are generally smaller and have shorter operating histories than companies trading in developed markets. Foreign investors may be required to register the proceeds of sales. Settlement of securities transactions in emerging markets may be subject to risk of loss and may be delayed more often than transactions settled in the U.S. Disruptions resulting from social and political factors may cause the securities markets to close. If extended closings were to occur, the liquidity and value of the Fund’s assets invested in corporate debt obligations of emerging market companies would decline.

Investment Controls; Repatriation. Foreign investment in emerging market country debt securities is restricted or controlled to varying degrees. These restrictions may at times limit or preclude foreign investment in certain emerging market country debt securities. Certain emerging market countries require government approval of investments by foreign persons, limit the amount of investments by foreign persons in a particular issuer, limit investments by foreign persons only to a specific class of securities of an issuer that may have less advantageous rights than the classes available for purchase by domiciliaries of the countries and/or impose additional taxes or controls on foreign investors or currency transactions. Certain emerging market countries may also restrict investment opportunities in issuers in industries deemed important to national interests.

Emerging market countries may require governmental approval for the repatriation of investment income, capital or proceeds of sale of securities by foreign investors. In addition, if a deterioration occurs in an emerging market country’s balance of payments, the country could impose temporary restrictions on foreign capital remittances. A Fund could be adversely affected by delays in, or a refusal to grant, any required governmental approval for repatriation of capital, as well as by the application to a Fund of any restrictions on investments. Investing in local markets in emerging market countries may require a Fund to adopt special procedures, seek local governmental approvals or take other actions, each of which may involve additional costs to a Fund.

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FIXED-INCOME SECURITIES RISK

This is the risk that the value of fixed-income securities in the Fund’s portfolio may decline for a number of reasons which relate directly to the issuer. This may include, among other things, management performance, the effects of financial leverage and reduced demand for a company’s goods and services. Fixed-income securities are also subject to credit risk, interest rate risk and liquidity risk.

FOREIGN SECURITIES RISK

This is the risk associated with investments in issuers that are located or do business in foreign countries. The High Income Opportunities Fund is subject to this risk because it may invest up to 40% of its assets in securities of non-U.S. issuers. The Fund’s investments in foreign securities may be less liquid and may experience more rapid and extreme changes in value than investments in securities of U.S. companies.

The securities markets of many foreign countries are relatively small, with a limited number of issuers and a small number of securities. In addition, foreign companies often are not subject to the same degree of regulation as U.S. companies. Reporting, accounting and auditing standards of foreign countries differ, in some cases significantly, from U.S. standards. Among other things, nationalization, expropriation or confiscatory taxation, currency blockage, political changes or diplomatic developments can cause the value of the Fund’s investments in a foreign country to decline. In the event of nationalization, expropriation or other confiscation, a fund that invests in foreign securities could lose its entire investment. These risks also apply to securities of foreign issuers traded in the United States or through depository receipt programs such as American Depository Receipts.

As described further under “Emerging Markets Risk” above, funds that invest in emerging markets may face greater foreign risk since emerging markets countries may be more likely to experience political and economic instability, and generally are subject to a greater degree to the risks generally applicable to foreign securities.

Although the Funds will invest only in U.S. dollar-denominated securities, the value of these securities may be adversely affected by changes in currency exchange rates.

HIGH-YIELD SECURITIES RISK

High-yield securities are generally rated below investment-grade quality. To be considered rated below investment-grade quality, none of the three major rating agencies (Moody’s, Fitch & S&P) must have rated the security in one of their respective top four rating categories at the time a Fund acquires the security or, if the security is unrated, Loomis Sayles must have determined it to be of comparable quality. These lower-rated securities, commonly known as “junk bonds,” may be considered speculative with respect to the issuer’s continuing ability to make principal and interest payments. Analysis of the creditworthiness of issuers of lower-rated securities may be more complex than for issuers of higher quality debt securities, and the Fund’s ability to achieve its investment objectives may, to the extent the Fund invests in lower-rated securities, be more dependent upon Loomis Sayles’ credit analysis than would be the case if the Fund were investing in higher quality securities. The issuers of these securities may be in default or have a currently identifiable vulnerability to default on their payments of principal and interest, or may otherwise be subject to present elements of danger with respect to payments of principal or interest. However, the Funds will not invest in securities that are in default as to payment of principal and interest at the time of purchase.

Lower-rated securities may be more susceptible to real or perceived adverse economic and competitive industry conditions than higher grade securities.

The prices of lower-rated securities have been found to generally be less sensitive to interest-rate changes than more highly rated investments, but more sensitive to adverse economic downturns or individual corporate developments. Yields on lower-rated securities will fluctuate. If the issuer of lower-rated securities defaults, the Funds may incur additional expenses to seek recovery.

The secondary markets in which lower-rated securities are traded may be less liquid than the market for higher-grade securities. A lack of liquidity in the secondary trading markets could adversely affect the price at which a Fund could sell a particular lower-rated security when necessary to meet liquidity needs or in response to a specific economic event, such as a deterioration in the creditworthiness of the issuer, and could adversely affect and cause large fluctuations in the NAV of the Fund’s shares. Adverse publicity and investor perceptions may decrease the values and liquidity of high yield securities generally.

It is reasonable to expect that any adverse economic condition could disrupt the market for lower-rated securities, have an adverse impact on the value of such securities and adversely affect the ability of the issuers of such securities to repay principal and pay interest thereon. New laws and proposed new laws may adversely impact the market for lower-rated securities.

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INFLATION/DEFLATION RISK

Inflation risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. Deflation risk is the risk that prices throughout the economy decline over time (the opposite of inflation). Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of a Fund’s portfolio.

INTEREST RATE RISK

This is the risk that changes in interest rates will affect the value of a Fund’s investments in fixed-income securities, such as bonds, notes, asset-backed securities and other income producing securities. Fixed-income securities are obligations of the issuer to make payments of principal and/or interest on future dates. Increases in interest rates may cause the value of a Fund’s investments to decline.

Even Funds that generally invest a significant portion of their assets in high quality fixed-income securities are subject to interest rate risk. Interest rate risk is greater for funds, such as the Funds, that generally invest a significant portion of their respective assets in lower rated fixed-income securities or comparable unrated securities (commonly known as “junk bonds”).

The Funds will be subject to increased interest rate risk to the extent that they invest in fixed-income securities with longer maturities or durations, as compared to if they invested in fixed-income securities with shorter maturities or durations.

Interest rate risk is compounded for funds that invest a significant portion of their assets in mortgage-related or other asset-backed securities because the value of mortgage-related securities and asset-backed securities generally is more sensitive to changes in interest rates than other types of fixed-income securities. When interest rates rise, the maturities of mortgage-related and asset-backed securities tend to lengthen, and the value of the securities decreases more significantly. In addition, these types of securities are subject to the risk of prepayment when interest rates fall, which generally results in lower returns because Funds that hold these types of securities must reinvest assets previously invested in these types of securities in fixed-income securities with lower interest rates.

The Funds also face increased interest rate risk when they invest in interest-only securities or fixed-income securities paying no current interest, such as zero-coupon securities, principal-only securities and fixed-income securities paying non-cash interest in the form of other fixed-income securities.

ISSUER RISK

The value of a Fund’s investments may decline for a number of reasons which directly relate to an issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. Because asset-backed securities are typically pools of other securities or assets, this risk also relates to the issuer of securities backing the asset-backed securities in which a Fund invests.

LEVERAGING RISK

When a Fund borrows money or otherwise leverages its portfolio, the value of an investment in the Fund will be more volatile, and all other risks are generally compounded. Funds face this risk if they create leverage by using investments such as reverse repurchase agreements, inverse floating-rate instruments or derivatives, or by borrowing money.

LIQUIDITY RISK

Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing a Fund from selling these illiquid securities at the price or at the time desired. Liquidity issues can also make it difficult to value a Fund’s investments, which also could have a negative impact on NAV. An unrated security may be less liquid than a comparable rated security and involves the risk that Loomis Sayles may not accurately evaluate the security’s comparative credit rating. Derivatives and securities that involve substantial interest rate risk or credit risk tend to involve greater liquidity risk. In addition, liquidity risk tends to increase to the extent the Fund invests in securities whose sale may be restricted by law or by contract, such as Rule 144A securities.

MANAGEMENT RISK

Management risk is the risk that Loomis Sayles’ investment techniques could fail to achieve a Fund’s objective and could cause your investment in a Fund to lose value. The Funds are subject to management risk because they are actively managed by Loomis Sayles. Loomis Sayles will apply its investment techniques and risk analyses in making investment decisions for each Fund, but

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there can be no guarantee that Loomis Sayles’ decisions will produce the desired results. For example, securities that Loomis Sayles expects may appreciate in value may in fact decline. Similarly, in some cases derivative and other investment techniques may be unavailable or Loomis Sayles may decide not to use them, even under market conditions where their use could have benefited a Fund.

MARKET RISK

Market risk is the risk that the value of a Fund’s investments will change as financial markets fluctuate and that prices overall may decline. The value of a company’s securities may fall as a result of factors that directly relate to that company, such as decisions made by its management or lower demand for the company’s products or services. A security’s value also may fall because of factors affecting not just the issuer of a security, but other companies in its industry or in a number of different industries, such as increases in production costs. The value of a Fund’s securities also may be affected by changes in financial market or other economic conditions, such as changes in interest rates or currency exchange rates. In addition, a company’s stock generally pays dividends only after the company makes required payments to holders of its bonds or other debt. For this reason, the value of the stock will usually react more strongly than bonds and other fixed-income securities to actual or perceived changes in the company’s financial condition or prospects. Market risk tends to be greater when a Fund invests in fixed-income securities with longer maturities.

Securities issued in initial public offerings tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. This may impact a Fund’s performance and result in higher portfolio turnover, which may increase the tax liability to shareholders and the brokerage expenses incurred by the Fund.

MORTGAGE-RELATED SECURITIES RISK

Mortgage-related securities, such as Government National Mortgage Association certificates or securities issued by the Federal National Mortgage Association, differ from traditional fixed-income securities. Among the major differences are that interest and principal payments are made more frequently, usually monthly, and that principal may be prepaid at any time because the underlying mortgage loans generally may be prepaid at any time. As a result, if a Fund purchases these assets at a premium, a faster-than-expected prepayment rate will reduce yield to maturity, and a slower-than-expected prepayment rate will increase yield to maturity. If a Fund purchases mortgage-related securities at a discount, faster-than-expected prepayments will increase, and slower-than-expected prepayments will reduce, yield to maturity. Prepayments, and resulting amounts available for reinvestment by the Fund, are likely to be greater during a period of declining interest rates and, as a result, are likely to be reinvested at lower interest rates. Accelerated prepayments on securities purchased at a premium may result in a loss of principal if the premium has not been fully amortized at the time of prepayment. These securities will decrease in value as a result of increases in interest rates generally, and they are likely to appreciate less than other fixed-income securities when interest rates decline because of the risk of prepayments.

The value of some mortgage-backed securities in which a Fund invests may be particularly sensitive to changes in prevailing interest rates, and the ability of a Fund to successfully utilize these instruments may depend in part upon the ability of the Adviser to forecast interest rates and other economic factors correctly. The risk of non-payment is greater for mortgage-related securities that are backed by mortgage pools that contain “subprime” or “Alt-A” loans (loans made to borrowers with weakened credit histories or with a lower capacity to make timely payments on their loans), but a level of risk exists for all loans. Market factors adversely affecting mortgage loan repayments may include a general economic turndown, high unemployment, a general slowdown in the real estate market, a drop in the market prices of real estate or an increase in interest rates resulting in higher mortgage payments by holders of adjustable-rate mortgages. The market for mortgage-backed securities (and other asset-backed securities) has experienced high volatility and a lack of liquidity. As a result, the value of many of these securities has significantly declined. There can be no assurance that these markets will become more liquid or less volatile, and it is possible that the value of these securities could decline further.

MORTGAGE DOLLAR ROLLS RISK

A mortgage dollar roll involves the sale of a security by a Fund and its agreement to repurchase the instrument at a specified time and price, and may be considered a form of borrowing for some purposes. A Fund will segregate assets determined to be liquid in an amount sufficient to meet its obligations under the transactions. A dollar roll involves potential risks of loss that are different from those related to the securities underlying the transactions. A Fund may be required to purchase securities at a higher price

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than may otherwise be available on the open market. Since the counterparty in the transaction is required to deliver a similar, but not identical, security to a Fund, the security that a Fund is required to buy under the dollar roll may be worth less than an identical security. There is no assurance that a Fund’s use of the cash that it receives from a dollar roll will provide a return that exceeds borrowing costs.

SMALL-CAPITALIZATION COMPANIES RISK

The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.

STRUCTURED NOTES RISK

Investment in structured notes involves certain risks, including the risk that the issuer may be unable or unwilling to satisfy its obligations to pay principal or interest, which are separate from the risk that the note’s reference instruments may move in a manner that is disadvantageous to the holder of the note. Structured notes, which are often illiquid, are also subject to additional risk such as market risk, liquidity risk and interest rate risk. The terms of certain structured notes may provide that a decline in the reference instrument may result in the interest rate or principal amount being reduced to zero. Structured notes may be more volatile than the underlying reference instruments or traditional debt instruments.

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management

Investment Adviser

Loomis Sayles, located at One Financial Center, Boston, Massachusetts 02111, serves as the investment adviser to the Funds. Loomis Sayles is a subsidiary of Natixis US, which is part of Natixis Asset Management Group, an international asset management group based in Paris, France. Founded in 1926, Loomis Sayles is one of the oldest investment firms in the U.S. with over $[ ] billion in assets under management as of December 31, 2009. Loomis Sayles has an extensive internal research staff. Loomis Sayles is responsible for making investment decisions for each Fund.

As previously described in the “Fund Fees and Expenses” section of the Fund summaries, an investor will either pay a “wrap” fee to the program sponsor and such sponsor will pay a fee to Natixis Advisors, or the investor, such as an institutional client of Loomis Sayles or Natixis Advisors, will pay a fee to Loomis Sayles or Natixis Advisors under a separate client agreement for advisory services. The Funds do not pay Loomis Sayles a monthly investment advisory fee, also known as management fees, for investment advisory services and, except as described below, Loomis Sayles pays the other ordinary expenses of the Funds.

Each Fund is a series of Loomis Sayles Funds I (the “Trust”). The Trust and not Loomis Sayles or its affiliates, will pay the following expenses: taxes payable by the Trust to federal, state or other governmental agencies; extraordinary expenses as may arise, including expenses incurred in connection with litigation, proceedings, other claims and the legal obligations of the Trust or the Funds to indemnify its trustees, officers, employees, shareholders, distributors and agents with respect thereto; brokerage fees and commissions (including dealer markups) and transfer taxes chargeable to the Trust in connection with the purchase and sale of portfolio securities for the Funds; costs, including any interest expenses, of borrowing money; costs of hedging transactions; costs of lending portfolio securities; and any expenses indirectly incurred through investments in other pooled investment vehicles.

A discussion of the factors considered by the Funds’ Board of Trustees in approving the Funds’ investment advisory contracts is available in the Funds’ annual reports for the fiscal year ended September 30, 2009.

Portfolio Managers

The following persons have had primary responsibility for the day-to-day management of each indicated Fund’s portfolio since the date stated below. Except where noted, each portfolio manager has been employed by Loomis Sayles for at least five years.

Matthew J. Eagan has served as portfolio manager of the Loomis Sayles High Income Opportunities Fund since its inception. Mr. Eagan serves as Vice President and Portfolio Manager of Loomis Sayles. He has over 19 years of investment experience. Mr. Eagan joined Loomis Sayles in 1997. Mr. Eagan received a B.A. from Northeastern University and an M.B.A. from Boston University and holds the designation of Chartered Financial Analyst.

Daniel J. Fuss has served as portfolio manager of the Loomis Sayles High Income Opportunities Fund since its inception. Mr. Fuss has been at Loomis Sayles since 1976 and is currently a Vice Chairman, Director and Managing Partner. He has over 50 years of investment experience. He graduated from Marquette University (B.S. and M.B.A.) and holds the designation of Chartered Financial Analyst.

Kathleen C. Gaffney has served as portfolio manager of the Loomis Sayles High Income Opportunities Fund since its inception. Ms. Gaffney joined Loomis Sayles in 1984. She received a B.A. from the University of Massachusetts at Amherst and has over 24 years of investment experience. She also holds the designation of Chartered Financial Analyst.

Fan Hu has served as portfolio manager of the Loomis Sayles Securitized Asset Fund since April 2006. Ms. Hu, Vice President of Loomis Sayles, began her investment career in 1997 and joined Loomis Sayles in 2006. Prior to joining Loomis Sayles, Ms. Hu was Vice President and mortgage-backed securities strategist at Columbia Management Group (or its predecessor) from 1998 to 2006. She received a B.A. from Nankai University in Tianjin, China, an M.S. from Montana State University and a Ph.D. from North Carolina State University. Ms. Hu is a Chartered Financial Analyst and has over 11 years of investment experience.

Clifton V. Rowe has served as portfolio manager of the Loomis Sayles Securitized Asset Fund since its inception. Mr. Rowe joined Loomis Sayles in 1992 and has over 16 years of investment experience. Prior to serving as a portfolio manager, Mr. Rowe was a trader with Loomis Sayles. Mr. Rowe received a B.B.A. from James Madison University and an M.B.A. from the University of Chicago. He holds the designation of Chartered Financial Analyst.

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Elaine M. Stokes has served as portfolio manager of the Loomis Sayles High Income Opportunities Fund since its inception. Ms. Stokes serves as a Vice President and Portfolio Manager of Loomis Sayles. She has over 21 years of investment experience. Ms. Stokes joined Loomis Sayles in 1988. She received a B.S. from St. Michael’s College.

Please see the SAI for information regarding portfolio manager compensation, other accounts under management by the portfolio managers and the portfolio managers’ ownership of securities in the Funds.

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general information

How Fund Shares Are Priced

NAV is the price of one share of a Fund without a sales charge and is calculated each business day using this formula:

The NAV of Fund shares is determined pursuant to policies and procedures approved by the Fund’s Board of Trustees as summarized below:

Generally, during times of substantial economic or market change, it may be difficult to place your order by phone. During these times, you may deliver your order in person to the Fund or send your order by mail as described in the sections “How to Purchase Shares” and “How to Redeem Shares.”

Generally, Fund securities are valued as follows:

Equity securities. Last sale price on the exchange or market where primarily traded or if there are no reported sales during the day, the closing bid price.

Debt securities (other than short-term obligations) . Based upon pricing service valuations, which determine valuations for normal, institutional-size trading units of such securities using market information, transactions for comparable securities and various relationships between securities which are generally recognized by institutional traders.

Short-term obligations (purchased with an original or remaining maturity of 60 days or less) . Amortized cost (which approximates market value).

Securities traded on foreign exchanges. Market price on the non-U.S. exchange, unless the Fund believes that an occurrence after the close of that exchange will materially affect the security’s value. In that case, the security may be fair-valued at the time the Fund determines its NAV by or pursuant to procedures approved by the Board of Trustees. When fair valuing securities, the Funds may, among other things, use modeling tools or other processes that may take into account factors such as securities market activity and/or significant events that occur after the close of the local market and before the time a Fund’s NAV is calculated.

Options. Domestic exchange-traded single equity option contracts are valued at the mean of the National Best Bid and Offer quotations. Exchange-traded index options and foreign exchange-traded single equity options are valued at the average of the closing bid and asked quotations.

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Futures. Unrealized gain or loss on the contract using current settlement price. When a settlement price is not used, futures contracts will be valued at their fair value as determined by or pursuant to procedures approved by the Board of Trustees.

Credit default swaps. Market value based on prices supplied by a pricing service, if available, or quotations obtained from broker-dealers.

Foreign Currency Forward Contracts. Interpolated prices determined from information provided by an independent pricing service.

All other securities. Fair market value as determined by the adviser of a Fund pursuant to procedures approved by the Board of Trustees.

As described above, if market prices are not readily available for a security, securities may not be priced on the basis of quotations from the primary market in which they are traded but rather may be priced by another method that the Board of Trustees believes is more likely to result in a price that reflects fair value (which is the amount that a Fund might reasonably expect to receive from a current sale of the security in the ordinary course of business). A Fund may also value securities at fair value or estimate their value pursuant to procedures approved by the Board of Trustees in other circumstances such as when extraordinary events occur after the close of the relevant market but prior to the close of the NYSE. This may include situations relating to a single issuer (such as a declaration of bankruptcy or a delisting of the issuer’s security from the primary market on which it has traded) as well as events affecting the securities markets in general (such as market disruptions or closings and significant fluctuations in U.S. and/or foreign markets). Fair value pricing may require subjective determinations about the value of a security, and fair values used to determine a Fund’s NAV may differ from quoted or published prices, or from prices that are used by others, for the same securities. In addition, the use of fair value pricing may not always result in adjustments to the prices of securities held by a Fund.

How to Purchase Shares

Each Fund is generally available for purchase in the U.S., Puerto Rico, Guam and the U.S. Virgin Islands. Except to the extent otherwise permitted by the Distributor, the Funds will only accept investments from U.S. citizens with a U.S. address or resident aliens with a U.S. address and a U.S. taxpayer identification number.

An investor may purchase Fund shares at NAV without a sales charge or other fee.

Shares of the Funds are offered exclusively to investors in “wrap fee” programs approved by Natixis Advisors and/or Loomis Sayles and to institutional advisory clients of Loomis Sayles or Natixis Advisors that, in each case, meet the Funds’ policies as established by Loomis Sayles.

A purchase order received by the Transfer Agent prior to the close of regular trading on the NYSE (normally 4:00 p.m., Eastern time), on a day the Funds are open for business, will be effected at that day’s NAV. An order received after the close of regular trading on the NYSE will be effected at the NAV determined on the next business day. The Funds are “open for business” on each day the NYSE is open for trading. Purchase orders will be accepted only on days on which the Funds are open for business.

Additional shares can be purchased if authorized by Natixis Advisors or Loomis Sayles and payment must be wired in federal funds to the Transfer Agent except when shares are purchased in exchange for securities acceptable to the Fund.

Purchases of a Fund’s shares will normally be made only in full shares, but may be made in fractional shares under certain circumstances. Certificates for shares will not be issued. The payment for shares to be purchased shall be wired to the Transfer Agent.

Subject to the approval of each Fund, an investor may purchase Institutional Class shares of the Fund with liquid securities and other assets that are eligible for purchase by the Fund (consistent with the Fund’s investment policies and restrictions) and that have a value that is readily ascertainable in accordance with the Fund’s valuation policies. These transactions will be effected only if Loomis Sayles deems the security to be an appropriate investment for a Fund. Assets purchased by a Fund in such a transaction will be valued in accordance with procedures adopted by the Fund. Each Fund reserves the right to amend or terminate this practice at any time.

Please see the section “Restrictions on Buying and Selling Shares” below for more information.

How To Redeem Shares

Shares normally can be redeemed only through the shareholder’s wrap program sponsor for shareholders owning shares through wrap accounts or by contacting Loomis Sayles, Natixis Advisors or the Transfer Agent for non-wrap program shareholders.

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Redemption requests for Fund shares are effected at the NAV per share next determined after receipt of a redemption request by the Transfer Agent. A redemption request received by the Transfer Agent prior to the close of regular trading on the NYSE, on a day the Funds are open for business, is effected at that day’s NAV. A redemption request received after that time is effected at the next business day’s NAV per share. Redemption proceeds normally will be wired within one business day after the redemption request, but may be delayed for up to seven days to provide for orderly liquidation of such holdings. Redemption proceeds will be sent by wire only. The Funds may suspend the right of redemption or postpone the payment date at times when the NYSE is closed, or during certain other periods as permitted under the federal securities laws.

The Funds and the Distributor reserve the right to redeem shares of any shareholder investing through a wrap program at the then-current value of such shares (which will be paid promptly to the shareholder) if the wrap sponsor is no longer approved by Loomis Sayles or Natixis Advisors. The sponsor will receive advance notice of any such mandatory redemption. Similarly, the Funds and the Distributor may redeem shares of any shareholder who no longer participates in an approved wrap program (for example, by withdrawing from the program). The Funds and the Distributor each reserve the right to redeem any shareholder for which Loomis Sayles or Natixis Advisors ceases to act as investment adviser. In addition, the Funds and the Distributor each reserve the right to redeem any shareholder if the shareholder’s continued investment in the Funds becomes inconsistent with each Fund’s policies, as established by Loomis Sayles.

It is highly unlikely that shares would ever be redeemed in-kind. However, in consideration of the best interests of the remaining investors, each Fund reserves the right to pay any redemption proceeds exceeding this amount in whole or in part by a distribution in-kind of securities held by the Funds in lieu of cash. When shares are redeemed in-kind, the redeeming registered investment adviser should expect to incur transaction costs upon the disposition of the securities received in the distribution. Each Fund agrees to redeem shares solely in cash up to the lesser of $250,000 or 1% of each Fund’s net assets during any 90-day period for any one registered investment adviser.

Generally, a transaction fee will be charged for expedited payment of redemption proceeds of $5.50 for wire transfers, $50 for international wire transfers or $20.50 for overnight delivery. These fees are subject to change.

Dividends and Distributions

It is the policy of each Fund to pay its shareholders each year, as dividends, all or substantially all of its net investment income. Each Fund expects to distribute all or substantially all of its net realized long- and short-term capital gains annually, after applying any available capital loss carryovers. To the extent permitted by law, the Board of Trustees may adopt a different schedule for making distributions as long as payments are made at least annually.

You may choose to:

If you do not select an option when you open your account, all distributions will be reinvested.

Other Purchase And Redemption Information

Each Fund reserves the right to create investment minimums in its sole discretion.

The Funds are required by federal regulations to obtain certain personal information from an investor and to use that information to verify an investor’s identity. A Fund may not be able to open an investor’s account if the requested information is not provided to the Fund or its delegate. The Funds reserve the right to refuse to open an account, close an account and redeem your shares at the then current price or take other such steps that the Funds deem necessary to comply with federal regulations if an investor’s identity is not verified.