MFS SERIES TRUST X (Form: 485BPOS, Received: 09/27/2016 10:45:23)

As filed with the Securities and Exchange Commission on September 27, 2016

	1933 Act File No. 33-1657
	1940 Act File No. 811-4492

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER THE SECURITIES ACT OF 1933

POST-EFFECTIVE AMENDMENT NO. 124

AND

REGISTRATION STATEMENT

UNDER THE INVESTMENT COMPANY ACT OF 1940

AMENDMENT NO. 123

MFS ® SERIES TRUST X

(Exact Name of Registrant as Specified in Charter)

111 Huntington Avenue, Boston, Massachusetts 02199-7632

(Address of Principal Executive Offices)

Registrant’s Telephone Number, including Area Code: 617-954-5000

Kristin V. Collins, Massachusetts Financial Services Company,

111 Huntington Avenue, Boston, MA 02199-7632

(Name and Address of Agent for Service)

APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:

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

o immediately upon filing pursuant to paragraph (b)

x on September 28, 2016 pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(i)

o on [date] pursuant to paragraph (a)(i)

o 75 days after filing pursuant to paragraph (a)(ii)

o on [date] pursuant to paragraph (a)(ii) of rule 485

If appropriate, check the following box:

o this post-effective amendment designates a new effective date for a previously filed post-effective amendment

September 28, 2016

PROSPECTUS

MFS ® Absolute Return Fund

The investment objective of the fund is to seek total return.

CLASS		TICKER SYMBOL
Class A		MRNAX
Class B		MRNBX
Class C		MRNCX
Class I		MRNIX
Class R1		MRNRX
Class R2		MRNSX
Class R3		MRNTX
Class R4		MRNUX
Class R6 (formerly Class R5)		MRNVX

Table of contents

SUMMARY OF KEY INFORMATION	2
INVESTMENT OBJECTIVE, STRATEGIES, AND RISKS	6
MANAGEMENT OF THE FUND	10
DESCRIPTION OF SHARE CLASSES	11
HOW TO PURCHASE, REDEEM, AND EXCHANGE SHARES	15
OTHER INFORMATION	18
FINANCIAL HIGHLIGHTS	21

The U.S. Securities and Exchange Commission and the Commodity Futures Trading Commission have not approved or disapproved the fund’s shares or determined whether this prospectus is accurate or complete. Anyone who tells you otherwise is committing a crime.

ART-PRO-092816

MFS Absolute Return Fund

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek total return.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 11 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Share Class

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

4.25

None

Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)

1.00

% #

4.00

1.00

None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Share Class	A		B		C		I		R1		R2		R3		R4		R6
Management Fee	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%
Distribution and/or Service (12b-1) Fees	0.25	%	1.00	%	1.00	%	None		1.00	%	0.50	%	0.25	%	None		None
Other Expenses	0.52	%	0.52	%	0.52	%	0.52	%	0.52	%	0.52	%	0.52	%	0.52	%	0.47	%
Total Annual Fund Operating Expenses	1.42	%	2.17	%	2.17	%	1.17	%	2.17	%	1.67	%	1.42	%	1.17	%	1.12	%
Fee Reductions and/or Expense Reimbursements 1	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%	(0.27	)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	1.15	%	1.90	%	1.90	%	0.90	%	1.90	%	1.40	%	1.15	%	0.90	%	0.85	%

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

1 Massachusetts Financial Services Company has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 1.15% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.90% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.90% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 1.40% of the class’ average daily net assets annually for Class R2 shares, and 0.85% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

MFS Absolute Return Fund

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.

The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund’s operating expenses remain the same.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR		3 YEARS		5 YEARS		10 YEARS
Class A Shares	$	537	$	830	$	1,144	$	2,032
Class B Shares assuming
redemption at end of period	$	593	$	953	$	1,340	$	2,291
no redemption at end of period	$	193	$	653	$	1,140	$	2,291
Class C Shares assuming
redemption at end of period	$	293	$	653	$	1,140	$	2,482
no redemption at end of period	$	193	$	653	$	1,140	$	2,482
Class I Shares	$	92	$	345	$	618	$	1,396
Class R1 Shares	$	193	$	653	$	1,140	$	2,482
Class R2 Shares	$	143	$	500	$	882	$	1,954
Class R3 Shares	$	117	$	423	$	751	$	1,679
Class R4 Shares	$	92	$	345	$	618	$	1,396
Class R6 Shares	$	87	$	329	$	591	$	1,339

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 36% of the average value of its portfolio.

Principal Investment Strategies

In managing the fund, MFS (Massachusetts Financial Services Company, the fund’s investment adviser) employs an absolute return investment approach, which means the fund seeks to earn a positive return regardless of market conditions. As a result, if this strategy is successful, it is expected that the fund will outperform the general equity market during periods of flat or negative equity market performance, will underperform during periods of strong positive equity market performance, and will typically produce less volatile returns than the general equity market.

MFS seeks to achieve the fund’s objective by generating returns from a combination of (1) individual security selection of primarily debt instruments and (2) a tactical asset allocation overlay primarily using derivative instruments to manage the fund’s exposure to asset classes, markets and currencies. Derivatives include futures, forward contracts, options, structured securities, and swaps.

The fund’s performance may not be correlated with the performance of the asset classes, markets or currencies represented by the individual investments selected by MFS.

Individual Security Selection: In selecting direct investments for the fund, MFS normally invests the fund’s assets primarily in debt instruments.

Debt instruments include U.S. Government securities, corporate bonds, foreign government securities, asset-backed securities and other obligations to repay money borrowed.

Of the fund’s investments in debt instruments, MFS generally invests substantially all of these investments in investment grade quality debt instruments.

While MFS may invest the fund’s assets in debt instruments of any effective maturity, MFS generally focuses on short and intermediate term debt instruments.

MFS may invest the fund’s assets in foreign securities.

While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives as part of its individual security selection process, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments.

Tactical Asset Allocation Overlay : MFS employs a top-down tactical asset allocation process to adjust the fund’s exposure to asset classes, markets and currencies based on its assessment of the relative attractiveness of such asset classes, markets and currencies. MFS manages the fund’s exposure to asset classes, markets and currencies primarily through the use of derivative instruments based on its proprietary quantitative models.

In managing the tactical overlay, MFS may increase or decrease the fund’s exposure to asset classes, markets and/or currencies resulting from MFS’ individual security selection based on MFS’ assessment of the risk/return potential of such asset classes, markets and/or currencies. MFS may also expose the fund to asset classes, markets and/or currencies in which its individual security selection has resulted in no or little exposure (e.g., real estate-related investments, equity securities, inflation-adjusted debt instruments). After taking into account the tactical overlay, the fund’s exposure to certain asset classes in which its individual security selection has resulted in no or little exposure will normally fall within the following ranges:

Asset Class		Range
U.S. and foreign equity securities		±15%
Inflation-adjusted debt instruments		±10%
Real estate-related investments		± 5%

After taking into account the tactical overlay, the fund’s exposure to the below investment grade quality debt instrument and long term debt instrument asset classes may at times be significant, and the fund may have significant exposure to issuers in a single country, a small number of countries, or a particular geographic region.

MFS may adjust the fund’s net exposure to asset classes, markets and/or currencies by taking net short positions in an asset class, market or currency if MFS believes the risk/return potential of such asset class, market or currency is unattractive. Alternatively, MFS may cause the fund to take net long positions in an asset class, market or currency if MFS believes such asset class, market or currency appears attractive.

MFS Absolute Return Fund

MFS may also use derivatives to seek to limit the fund’s exposure to certain extreme market events.

MFS’ tactical allocation process for the fund will typically make extensive use of derivatives.

Principal Risks

As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Allocation Risk: MFS’ assessment of the risk/return potential of asset classes, markets and currencies, and its adjustments to the fund’s exposure to asset classes, markets, and currencies may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Investment Strategy Risk : There is no assurance that the fund will earn a positive return over the long term or for any year or period of years. The fund’s strategy to manage its exposure to asset classes, markets, and currencies may not produce the intended results. In addition, the strategies MFS may implement to limit the fund’s exposure to certain extreme market events may not work as intended, and the costs associated with such strategies will reduce the fund’s returns.

Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.

Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities, or that do not pay current interest.

Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.

Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk: Investments in emerging markets can involve additional and greater risks than the risks associated with investments in developed foreign markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, and greater political, social, and economic instability than developed markets.

Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, and other conditions, and a decline in the value of a foreign currency versus the U.S. dollar reduces the value in U.S. dollars of investments denominated in that foreign currency.

Geographic Focus Risk: Issuers in a single country, a small number of countries, or a particular geographic region can react similarly to market, currency, political, economic, regulatory, geopolitical, and other conditions, and the fund’s performance will be affected by the conditions in the countries or regions in which the fund’s assets are invested.

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction.

Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.

Stock Market/Company Risk: Stock markets are volatile and can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions, as well as to investor perceptions of these conditions. The price of an equity security can decrease significantly in response to these conditions, and these conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the market in general.

Real Estate-Related Investment Risk: The risks of investing in real estate-related securities include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the real estate investment trusts (REITs) manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may

MFS Absolute Return Fund

have to sell certain of these investments at a price or time that is not advantageous in order to meet redemptions or other cash needs.

Investment Selection Risk: MFS’ investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. Investments selected using quantitative models may not produce the intended results due to the factors used in the models, the weight placed on each factor in the models, changing sources of market return, and technical issues in the design, development, implementation, and maintenance of the models (e.g., incomplete or inaccurate data, programming or other software issues, and technology failures).

Performance Information

The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund’s performance over time compares with that of a broad measure of market performance.

The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606.

Class A Bar Chart. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown.

The total return for the six-month period ended June 30, 2016, was 4.08%. During the period(s) shown in the bar chart, the highest quarterly return was 1.59% (for the calendar quarter ended December 31, 2012) and the lowest quarterly return was (2.06)% (for the calendar quarter ended September 30, 2015).

Performance Table.

Average Annual Total Returns

(For the Periods Ended December 31, 2015)

Share Class	1 YEAR		LIFE (INCEPTION 3-30-2011)
Returns Before Taxes
B Shares	(7.68	)%	(2.23	)%
C Shares	(4.80	)%	(1.81	)%
I Shares	(2.71	)%	(0.80	)%
R1 Shares	(3.72	)%	(1.79	)%
R2 Shares	(3.32	)%	(1.32	)%
R3 Shares	(3.07	)%	(1.08	)%
R4 Shares	(2.82	)%	(0.83	)%
R6 Shares	(2.87	)%	(0.79	)%
A Shares	(7.18	)%	(1.97	)%
Returns After Taxes on Distributions
A Shares	(7.41	)%	(2.30	)%
Returns After Taxes on Distributions and Sale of Fund Shares
A Shares	(4.06	)%	(1.61	)%
Index Comparison (Reflects no deduction for fees, expenses, or taxes)
BofA Merrill Lynch 0-3 Month U.S. Treasury Bill Index	0.02	%	0.04	%

Aft er-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown.

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager	Since	Title
James J. Calmas	2011	Investment Officer of MFS
Benjamin Nastou	2011	Investment Officer of MFS
Natalie I. Shapiro	2011	Investment Officer of MFS

Purchase and Sale of Fund Shares

You may purchase and redeem shares of the fund each day the New York Stock Exchange is open for trading. You may purchase or redeem shares either by having your financial intermediary process your purchase or redemption, or through MFS Service Center, Inc. (MFSC) by overnight mail (MFSC, c/o Boston Financial Data Services, 30 Dan Road, Canton, MA 02021-2809), by mail ([Fund Name], P.O. Box 55824, Boston, MA 02205-5824), by telephone (1-800-225-2606), or via the Internet at mfs.com (MFS Access).

MFS Absolute Return Fund

The fund’s initial and subsequent investment minimums generally are as follows:

Class	Initial Minimum	Subsequent Minimum
Class A, Class B, Class C	None – automatic investment plans and certain asset-based fee programs $25 – employer-sponsored retirement plans $250 – Traditional and Roth IRAs $1,000 – other accounts	$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives None – other purchases
Class I, Class R1, Class R2, Class R3, Class R4, Class R6	None	None

Taxes

If your shares are held in a taxable account, the fund’s distributions will be taxed to you as ordinary income and/or capital gains. If your shares are held in a tax-advantaged account, you will generally be taxed only upon withdrawals from the account.

Payments to Broker/Dealers and Other Financial Intermediaries

If you purchase shares of the fund through a broker/dealer or other financial intermediary (such as a bank), the fund, MFS, and/or MFS’ affiliates may pay the financial intermediary for the sale of shares of a fund and/or the servicing of shareholder accounts. These payments may create a conflict of interest by influencing your broker/dealer or other financial intermediary and your salesperson to recommend the fund over another investment. Ask your financial intermediary or visit your financial intermediary’s Web site for more information.

Investment Objective, Strategies, and Risks

Investment Objective

The fund’s investment objective is to seek total return. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

In managing the fund, MFS employs an absolute return investment approach. Unlike many mutual funds, the fund is not managed with a goal of outperforming an index of securities or other funds. The investment returns of mutual funds that are managed relative to an index may be positive or negative and will tend to reflect the general direction of the markets. In contrast, the fund seeks to earn a positive return regardless of market conditions. As a result, if this strategy is successful, it is expected that the fund will outperform the general equity market during periods of flat or negative equity market performance, will underperform during periods of strong positive equity market performance, and will typically produce less volatile returns than the general equity market.

The fund’s performance may not be correlated with the performance of the asset classes, markets or currencies represented by the individual investments selected by MFS.

Some portion of the fund’s assets will be held in cash due to collateral requirements for the fund’s investments in derivatives, purchase and redemption activity, and other short term cash needs.

Individual Security Selection: In selecting direct investments for the fund, MFS normally invests the fund’s assets primarily in debt instruments.

Of the fund’s investments in debt instruments, MFS generally invests substantially all of these investments in investment grade quality debt instruments.

While MFS may invest the fund’s assets in debt instruments of any effective maturity, MFS generally focuses on short and intermediate term debt instruments. In determining an instrument’s effective maturity, MFS uses the instrument’s stated maturity or, if applicable, an earlier date on which MFS believes it is probable that a maturity-shortening device (such as a call, put, pre-refunding, prepayment or redemption provision, or an adjustable coupon) will cause the instrument to be repaid. Such an earlier date can be substantially shorter than the instrument’s stated maturity.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up investment approach to buying and selling investments for the fund. Debt investments are selected primarily based on fundamental analysis of individual instruments and their issuers in light of issuers’ financial condition and market, economic, political, and regulatory conditions. Factors considered may include the instrument’s credit quality and terms, any underlying assets and their credit quality, and the issuer’s management ability, capital structure, leverage, and ability to meet its current obligations. Quantitative models that systematically evaluate the structure of the debt instrument and its features may also be considered.

Asset Class		Range
U.S. and foreign equity securities		±15%
Inflation-adjusted debt instruments		±10%
Real estate-related investments		± 5%

MFS Absolute Return Fund

MFS may also use derivatives to seek to limit the fund’s exposure to certain extreme market events.

MFS’ tactical allocation process for the fund will typically make extensive use of derivative instruments, and MFS may invest the fund’s assets in derivatives to the extent permitted by the Investment Company Act of 1940.

Principal Investment Types

The principal investment types in which the fund may invest are:

Derivatives: Derivatives are financial contracts whose value is based on the value of one or more underlying indicators or the difference between underlying indicators. Underlying indicators may include a security or other financial instrument, asset, currency, interest rate, credit rating, commodity, volatility measure, or index. Derivatives often involve a counterparty to the transaction. Derivatives include futures, forward contracts, options, structured securities, and swaps.

Debt Instruments: Debt instruments represent obligations of corporations, governments, and other entities to repay money borrowed. The issuer or borrower usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the instrument. During certain market conditions, some debt instruments can trade at a negative interest rate; i.e., the price to purchase the debt instrument is more than the present value of expected interest payments and principal due at the maturity of the instrument. Some debt instruments, such as zero coupon bonds or payment-in-kind bonds, do not pay current interest. Other debt instruments, such as certain mortgage-backed and other asset-backed securities, make periodic payments of interest and/or principal. Some debt instruments are partially or fully secured by collateral supporting the payment of interest and principal.

U.S. Government Securities: U.S. Government securities are securities issued or guaranteed as to the payment of principal and interest by the U.S. Treasury, by an agency or instrumentality of the U.S. Government, or by a U.S. Government-sponsored entity. Certain U.S. Government securities are not supported as to the payment of principal and interest by the full faith and credit of the U.S. Treasury or the ability to borrow from the U.S. Treasury. Some U.S. Government securities are supported as to the payment of principal and interest only by the credit of the entity issuing or guaranteeing the security. U.S. Government securities include mortgage-backed securities and other types of asset-backed securities issued or guaranteed by the U.S. Treasury, by an agency or instrumentality of the U.S. Government, or by a U.S. Government-sponsored entity.

Corporate Bonds: Corporate bonds are debt instruments issued by corporations or similar entities.

Foreign Government Securities: Foreign government securities are debt instruments issued, guaranteed, or supported, as to the payment of principal and interest, by foreign governments, foreign government agencies, foreign semi-governmental entities or supranational entities, or debt instruments issued by entities organized and operated for the purpose of restructuring outstanding foreign government securities. Foreign government securities may not be supported as to the payment of principal and interest by the full faith and credit of the foreign government.

Asset-Backed Securities: Asset-backed securities include mortgage-backed securities and other securities that represent interests in assets or payments from assets, such as loans or receivables. Different asset-backed securities provide different rights with respect to the underlying assets or payments from those assets depending on the terms of the security. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. Asset-backed securities typically involve a third party responsible for servicing the instrument and performing operational functions. Certain asset-backed securities offer multiple classes that differ in terms of their priority to receive principal and/or interest payments under the terms of the security. Certain mortgage-backed securities are issued on a delayed delivery or forward commitment basis where payment and delivery take place at a future date.

Real Estate-Related Investments: Real estate-related investments include real estate investment trusts (REITs), issuers similar to REITs formed under the laws of non-U.S. countries, and other U.S. and foreign issuers that earn at least 50% of their gross revenues or net profits from real estate activities or from products or services related to the real estate sector. Real estate activities include owning, developing, managing, or acting as a broker for real estate. Examples of real estate products or services include building supplies and mortgage servicing. REITs are pooled investment vehicles that invest primarily in income-producing real estate or real estate-related loans or interests. Equity REITs invest most of their assets directly in U.S. or foreign real property, receive most of their income from rents and may also realize gains by selling appreciated property. Mortgage REITs invest most of their assets in real estate mortgages and receive most of their income from interest payments. Hybrid REITs combine the characteristics of both equity REITs and mortgage REITs.

Principal Risks

The share price of the fund will change daily based on changes in interest rates and market, economic, industry, political, regulatory, geopolitical, and other conditions. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Investment Strategy Risk : There is no assurance that the fund will earn a positive return over the long term or for any year or period of years. The fund’s strategy to manage its exposure to asset classes, markets, and currencies may not produce the intended results if MFS is unable to adjust the fund’s asset class, market and currency exposures as it would like because appropriate derivatives or other investments are not available or the derivatives or other investments MFS selects do not correlate as intended with the asset class, market, and currency exposures resulting from MFS’ individual

MFS Absolute Return Fund

security selection. In addition, the strategies MFS may implement to limit the fund’s exposure to certain extreme market events may not work as intended, and the costs associated with such strategies will reduce the fund’s returns.

Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to, and potentially greater than, the risks of the underlying indicator(s). Gains or losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. Derivatives can involve leverage. Derivatives can be complex instruments and can involve analysis and processing that differs from that required for other investment types used by the fund. If the value of a derivative does not change as expected relative to the value of the market or other indicator the derivative is intended to provide exposure to, the derivative may not have the effect intended. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments.

Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of changes in, market, economic, industry, political, regulatory, geopolitical, and other conditions that affect a particular type of instrument, issuer, or borrower, and/or that affect the debt market generally. Certain events, such as market or economic developments, including increasing and negative interest rates, regulatory or government actions, natural disasters, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and may lead to periods of high volatility and reduced liquidity in the debt market or a portion of the debt market.

Interest Rate Risk: The price of a debt instrument changes in response to interest rate changes. Interest rates change in response to the supply and demand for credit, government monetary policy and action, inflation rates, and other factors. In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities, or that do not pay current interest. In addition, short-term and long-term interest rates, and interest rates in different countries, do not necessarily move in the same direction or by the same amount. An instrument’s reaction to interest rate changes depends on the timing of its interest and principal payments and the current interest rate for each of those time periods. Instruments with floating interest rates can be less sensitive to interest rate changes. The price of an instrument trading at a negative interest rate responds to interest rate changes like other debt instruments; however, an instrument purchased at a negative interest rate is expected to produce a negative return if held to maturity.

Credit Risk: The price of a debt instrument depends, in part, on the issuer’s or borrower’s credit quality or ability to pay principal and interest when due. The price of a debt instrument is likely to fall if an issuer or borrower defaults on its obligation to pay principal or interest, if the instrument’s credit rating is downgraded by a credit rating agency, or based on other changes in the financial condition of the issuer or borrower. For certain types of instruments, including derivatives, the price of the instrument depends in part on the credit quality of the counterparty to the transaction. For other types of debt instruments, including asset-backed securities, the price of the debt instrument also depends on the credit quality and adequacy of the underlying assets or collateral as well as whether there is a security interest in the underlying assets or collateral. Enforcing rights, if any, against the underlying assets or collateral may be difficult.

Below investment grade quality debt instruments can involve a substantially greater risk of default or can already be in default, and their values can decline significantly over short periods of time. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics with respect to capacity to pay interest and principal. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments. The market for below investment grade quality debt instruments can be less liquid, especially during periods of recession or general market decline.

Foreign Risk: Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. Political, social, and economic developments, U.S. and foreign government action such as the imposition of currency or capital controls, economic and trade sanctions or embargoes, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Economies and financial markets are becoming more connected, which increases the likelihood that conditions in one country or region can adversely impact issuers in different countries and regions. Less stringent regulatory, accounting, and disclosure requirements for issuers and markets are more common in certain foreign countries. Enforcing legal rights can be difficult, costly, and slow in certain foreign countries, and can be particularly difficult against foreign governments. Additional risks of foreign investments include trading, settlement, custodial, and other operational risks, and withholding and other taxes. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, and other conditions than the U.S. market.

Emerging Markets Risk: Emerging market investments can involve additional and greater risks than the risks associated with investments in developed foreign markets securities. Emerging markets typically have less developed economies and markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, less trading volume, and more government involvement in the economy than developed countries. Emerging markets can also be subject to greater political, social, and economic instability. These factors can make emerging market investments more volatile and less liquid than investments in developed markets.

Currency Risk: A decline in the value of a foreign currency relative to the U.S. dollar reduces the value of the foreign currency and investments denominated in that currency. In addition, the use of foreign exchange contracts to reduce foreign currency exposure can eliminate some or all of the benefit of an increase in the value of a foreign currency versus the U.S. dollar. The value of foreign currencies relative to the U.S. dollar fluctuates in response to, among other factors, interest rate changes, intervention (or failure to intervene) by the U.S. or foreign governments, central banks, or supranational entities such as the International Monetary Fund, the imposition of currency controls, and other political or regulatory conditions in the U.S. or abroad. Foreign currency values can decrease significantly both in the short term and over the long term in response to these and other conditions.

MFS Absolute Return Fund

difficulties, levels of inflation and unemployment, fiscal and monetary controls, and political and social instability in such countries and regions. If MFS invests a significant percentage of the fund’s assets in issuers located in a single country, a small number of countries, or a particular geographic region, the fund’s performance will be affected by the conditions in that country, countries, or region.

Leveraging Risk: Certain transactions and investment strategies can result in leverage. Leverage involves investment exposure in an amount exceeding the initial investment. In transactions involving leverage, a relatively small change in an underlying indicator can lead to significantly larger losses to the fund. Leverage can cause increased volatility by magnifying gains or losses.

Counterparty and Third Party Risk: Transactions involving a counterparty other than the issuer of the instrument, including clearing organizations, or a third party responsible for servicing the instrument or effecting the transaction, are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction.

Prepayment/Extension Risk: Many types of debt instruments, including mortgage-backed securities, asset-backed securities, certain corporate bonds, and municipal housing bonds, and certain derivatives, are subject to the risk of prepayment and/or extension. Prepayment occurs when unscheduled payments of principal are made or the instrument is called or redeemed prior to an instrument’s maturity. When interest rates decline, the instrument is called, or for other reasons, these debt instruments may be repaid more quickly than expected. As a result, the holder of the debt instrument may not be able to reinvest the proceeds at the same interest rate or on the same terms, reducing the potential for gain. When interest rates increase or for other reasons, these debt instruments may be repaid more slowly than expected, increasing the potential for loss. In addition, prepayment rates are difficult to predict and the potential impact of prepayment on the price of a debt instrument depends on the terms of the instrument.

Stock Market Risk: The price of an equity security fluctuates in response to issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions, as well as to investor perceptions of these conditions. Prices can decrease significantly in response to these conditions, and these conditions can affect a single issuer, issuers within a broad market sector, industry or geographic region, or the market in general. Different parts of the market and different types of securities can react differently to these conditions. For example, the stocks of growth companies can react differently from the stocks of value companies, and the stocks of large cap companies can react differently from the stocks of small cap companies. Certain events, such as natural disasters, terrorist attacks, war, and other geopolitical events, can have a dramatic adverse effect on stock markets.

Company Risk: Changes in the financial condition of a company or other issuer, changes in specific market, economic, industry, political, regulatory, geopolitical, and other conditions that affect a particular type of investment or issuer, and changes in general market, economic, political, regulatory, geopolitical and other conditions can adversely affect the price of an investment. The price of securities of smaller, less well-known issuers can be more volatile than the price of securities of larger issuers or the market in general.

Real Estate-Related Investment Risk: The risks of investing in real estate-related investments include certain risks associated with the direct ownership of real estate and the real estate industry in general. Real estate-related investments are affected by general, regional and local economic conditions; difficulties in valuing and disposing of real estate; and fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations, and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. Equity REITs may be affected by changes in the value of the underlying property owned by the trusts. Mortgage REITs may be affected by default or payment problems relating to underlying mortgages, the quality of credit extended and prepayments of the underlying mortgages. Equity and mortgage REITs could be adversely affected by failure to qualify for the favorable tax treatment available to REITs under the Internal Revenue Code of 1986, as amended, or to maintain their exemption from registration under the Investment Company Act of 1940, as amended. The securities of small real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

Liquidity Risk: Certain investments and types of investments are subject to restrictions on resale, may trade in the over-the-counter market, or may not have an active trading market due to adverse market, economic, industry, political, regulatory, geopolitical, and other conditions. At times, all or a large portion of segments of the market may not have an active trading market. Without an active trading market, it may be difficult to value, and it may not be possible to sell, these investments and the fund may have to sell certain of these investments at a price or time that is not advantageous in order to meet redemptions or other cash needs.

Other Investment Strategies and Risks

Active and Frequent Trading: MFS may engage in active and frequent trading in pursuing the fund’s principal investment strategies. Frequent trading increases transaction costs, which may reduce the fund’s return. Frequent trading can also increase the possibility of capital gain distributions. Capital gain distributions generally increase your tax liability unless you hold your shares through a tax-advantaged or exempt vehicle.

Temporary Defensive Strategy: In response to adverse market, economic, industry, political, or other conditions, MFS may depart from the fund’s principal investment strategies by temporarily investing for defensive purposes. When MFS invests defensively, different factors could affect the fund’s performance and the fund may not achieve its investment objective. In addition, the defensive strategy may not work as intended.

Further Information on Investment Strategies, Types, and Risks: Information about investment strategies and investment types not described in the Prospectus and the risks associated with those investment strategies and investment types are described in the fund’s SAI.

MFS Absolute Return Fund

Management of the Fund

Investment Adviser

MFS, located at 111 Huntington Avenue, Boston, Massachusetts, serves as the investment adviser for the fund. Subject to the supervision of the fund’s Board of Trustees, MFS is responsible for managing the fund’s investments, executing transactions, and providing related administrative services and facilities under an Investment Advisory Agreement between the fund and MFS.

For the fiscal year ended May 31, 2016, the fund paid MFS an effective management fee equal to 0.64% of the fund’s average daily net assets.

The management fee set forth in the Investment Advisory Agreement is 0.65% of the fund’s average daily net assets annually up to $1 billion, 0.55% of the fund’s average daily net assets annually in excess of $1 billion and up to $2.5 billion, and 0.50% of the fund’s average daily net assets annually in excess of $2.5 billion.

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the fiscal year ended May 31, 2016, this management fee reduction amounted to less than 0.01% of the fund’s average daily net assets.

MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 1.15% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.90% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.90% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 1.40% of the class’ average daily net assets annually for Class R2 shares, and 0.85% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

A discussion regarding the basis for the Board of Trustees’ approval of the Investment Advisory Agreement is available in the fund’s semiannual report for the six-month period ended November 30, 2015.

MFS is America’s oldest mutual fund organization. MFS and its predecessor organizations have a history of money management dating from 1924 and the founding of the first mutual fund, Massachusetts Investors Trust. Net assets under the management of the MFS organization were approximately $439 billion as of July 31, 2016.

Disclosure of Portfolio Holdings . The fund has established a policy with respect to the disclosure of fund portfolio holdings. A description of this policy is provided in the SAI.

The following information is generally available to you on mfs.com (once you have selected “Individual Investor” as your role, click on “Products & Services” and “Mutual Funds.” Next, choose the fund’s name in the “Select a fund” menu, then click on the “Characteristics” tab):

Information		Approximate Date of Posting To Web Site
Fund’s top 10 holdings as of each month’s end		14 days after month end
Fund’s full holdings as of each month’s end		24 days after month end

Holdings also include short positions, if any.

Note that the fund or MFS may suspend the posting of this information or modify the elements of this Web posting policy without notice to shareholders. Once posted, the above information will generally remain available on the Web site until at least the date on which the fund files a Form N-CSR or Form N-Q for the period that includes the date as of which the Web site information is current.

Portfolio Manager(s)

Information regarding the portfolio manager(s) of the fund is set forth below. Further information regarding the portfolio manager(s), including other accounts managed, compensation, ownership of fund shares, and possible conflicts of interest, is available in the fund’s SAI.

Portfolio Manager	Primary Role	Five Year History
James J. Calmas	Debt Instruments Portfolio Manager	Employed in the investment area of MFS since 1988
Benjamin Nastou	Tactical Asset Allocation Overlay Portfolio Manager	Employed in the investment area of MFS since 2001
Natalie I. Shapiro	Tactical Asset Allocation Overlay Portfolio Manager	Employed in the investment area of MFS since 1997

Administrator

MFS provides the fund with certain financial, legal, and other administrative services under a Master Administrative Services Agreement between the fund and MFS. Under the Agreement, MFS is paid an annual fee for providing these services.

Distributor

MFS Fund Distributors, Inc. (“MFD”), a wholly owned subsidiary of MFS, is the distributor of shares of the fund.

Shareholder Servicing Agent

MFS Service Center, Inc. (“MFSC”), a wholly owned subsidiary of MFS, provides dividend and distribution disbursing and transfer agent and recordkeeping functions in connection with the issuance, transfer, and redemption of each class of shares of the fund under a Shareholder Servicing Agent Agreement. MFSC receives a fee based on the costs it incurs in providing these services and a target profit margin. In addition, MFSC is reimbursed for payments made to service providers that provide certain sub-accounting and other shareholder services (shareholder servicing payments) and its out-of-pocket expenses. No shareholder servicing payments are made for Class R6 shares.

MFS Absolute Return Fund

Special Servicing Agreement

Under a Special Servicing Agreement among MFS, certain funds which invest primarily in other funds advised by MFS (“MFS Fund-of-Funds”), and the fund, the fund pays to MFSC a portion of the transfer agent-related expenses of each MFS Fund-of-Funds that invests in the fund, including sub-accounting fees payable to financial intermediaries, to the extent such payments are less than the amount of benefits realized or expected to be realized by the fund from the investment by the MFS Fund-of-Funds.

Description of Share Classes

The fund offers Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, Class R4, and Class R6 shares through this prospectus. All classes of the fund have the same investment objective and investments, but each class has its own sales charge and expense structure. Your financial intermediary may also charge you additional fees, commissions, or other charges. You should consult with your financial intermediary to help you determine which class is most appropriate for you.

Class I shares generally are available only to the following eligible investors:

· certain retirement plans established for the benefit of employees and former employees of MFS or its affiliates;

· defined benefit retirement plans, endowments or foundations;

· bank trust departments or law firms acting as trustee or manager for trust accounts;

· investors who purchase shares through asset-based fee programs available through financial intermediaries;

· employees and former employees of MFS and its subsidiaries who were employed by MFS or its subsidiaries on or after January 1, 2013, trusts, pension, profit-sharing or other retirement plans for the sole benefit of such persons, and joint accounts with such persons’ spouses or legal equivalents under applicable state law; and

· trustees and former trustees of any investment company for which MFD serves as a distributor and who served as trustee on or after January 1, 2013, trusts, pension, profit-sharing or other retirement plans for the sole benefit of such persons, and joint accounts with such persons’ spouses or legal equivalents under applicable state law.

In addition, MFD may accept, in its sole discretion, investments in Class I shares from purchasers not listed above.

Class R6 shares generally are available only to Employer Retirement Plans, investment companies distributed by MFD, endowments and foundations, local, city and state agencies (or entities acting on their behalf), funded welfare benefit plans (e.g., Voluntary Employees’ Beneficiary Association (VEBA) and Other Post-Employment (OPEB) plans), unaffiliated registered investment companies, and collective investment trusts.

Class R1, Class R2, Class R3, Class R4, and Class R6 shares generally are not available to traditional and Roth IRAs, Coverdell Educational Savings Accounts, SEPs, SAR-SEPs, SIMPLE IRAs, salary reduction only 403(b) plans, and 529 tuition plans.

Shareholders may be able to convert between Class A shares and Class I shares of the fund if they satisfy eligibility requirements for the other class, if any. Class I shareholders may be able to convert their Class I shares to Class R6 shares of the fund if they satisfy eligibility requirements of Class R6 shares.

Class C shareholders may be able to convert their Class C shares not subject to a CDSC to Class I shares of the fund if they satisfy eligibility requirements of Class I shares.

If a shareholder converts from one share class to another share class of the fund, as described above, the transaction will be based on the respective net asset value of each class as of the trade date for the conversion. Consequently, the converting shareholder may receive fewer shares or more shares than originally owned, depending on that day’s net asset values. The total value of the initially held shares, however, will equal the total value of the converted shares received. A conversion between share classes in the same fund, as described above, is a nontaxable event.

Sales Charges and Waivers or Reductions

You may be subject to an initial sales charge when you purchase Class A shares, or a CDSC when you redeem Class A, Class B, or Class C shares. These sales charges are paid to MFD.

In the circumstances described below, you may qualify for a sales charge waiver or reduction for purchases or redemptions of Class A, Class B, or Class C shares. In addition, other sales charge waivers or reductions apply to certain transactions by retirement plans, Section 529 tuition programs, and certain other groups (e.g., affiliated persons of MFS) and with respect to certain types of investment programs (e.g., asset-based fee programs available through certain financial intermediaries). Details regarding the types of investment programs and categories of investors eligible for these waivers or reductions are provided in the SAI, which is available to you free of charge and on the fund’s Web site at mfs.com . Some of these programs and waivers or reductions are not available to you if your shares are held through certain types of accounts, such as retirement accounts and 529 plans, or certain accounts that you have with your financial intermediary. Waivers or reductions may be eliminated, modified, and added at any time without providing advance notice to shareholders.

Class A Shares. You may purchase Class A shares at the offering price (which includes the applicable initial sales charge).

The amount of the initial sales charge you pay when you buy Class A shares differs depending upon the amount you invest, as follows:

	INITIAL SALES CHARGE AS PERCENTAGE OF:
Amount of Purchase	GROSS PURCHASE AMOUNT (OFFERING PRICE*)		NET AMOUNT INVESTED
Less than $100,000	4.25	%	4.44	%
$100,000 but less than $250,000	3.25	%	3.36	%
$250,000 but less than $500,000	2.25	%	2.30	%
$500,000 but less than $1,000,000	1.75	%	1.78	%
$1,000,000 or more	None		None

* Offering price is calculated by dividing the net asset value of a share by the difference between 1 and the initial sales charge percentage. Because the offering price is rounded to two decimal places, actual sales charges you pay may be more or less than those calculated using these percentages.

MFS Absolute Return Fund

As of October 1, 2016, the above chart is restated as follows:

	INITIAL SALES CHARGE AS PERCENTAGE OF:
Amount of Purchase	GROSS PURCHASE AMOUNT (OFFERING PRICE*)		NET AMOUNT INVESTED
Less than $100,000	4.25	%	4.44	%
$100,000 but less than $250,000	3.25	%	3.36	%
$250,000 but less than $500,000	2.25	%	2.30	%
$500,000 or more	None		None

You may purchase Class A shares without an initial sales charge when you invest $1 million or more in Class A shares. However, for purchasers other than Employer Retirement Plans, a CDSC of 1% will generally be deducted from your redemption proceeds if you redeem within 18 months of purchase.

As of October 1, 2016, the above paragraph is restated as follows:

You may purchase Class A shares without an initial sales charge when you invest $500,000 or more in Class A shares. However, for purchasers other than Employer Retirement Plans, a CDSC of 1% will generally be deducted from your redemption proceeds if you redeem within 18 months of purchase.

Class B Shares. You may purchase Class B shares at net asset value without an initial sales charge, but if you redeem your shares within the first six years after purchase, you may be subject to a CDSC (declining from 4% during the first year to 0% after six years).

The CDSC is imposed according to the following schedule:

Year of redemption after purchase		1st		2nd		3rd		4th		5th		6th		7th
Contingent deferred sales charge		4	%	4	%	3	%	3	%	2	%	1	%	0	%

If you hold Class B shares for approximately eight years, they will convert to Class A shares of the fund. All Class B shares you acquire through the reinvestment of dividends and distributions will be held in a separate sub-account. Each time any Class B shares in your account convert to Class A shares, a proportionate number of the Class B shares in the sub-account will also convert to Class A shares.

Class C Shares. You may purchase Class C shares at net asset value without an initial sales charge. However, a CDSC of 1% will generally be deducted from your redemption proceeds if you redeem within 12 months of your purchase.

Class I Shares. Eligible investors may purchase Class I shares at net asset value without an initial sales charge or a CDSC upon redemption.

Class R1, Class R2, Class R3, Class R4, and Class R6 Shares. Eligible investors may purchase Class R1, Class R2, Class R3, Class R4, and Class R6 shares at net asset value without an initial sales charge or a CDSC upon redemption.

Sales Charge Waivers or Reductions. Below is a summary of certain investor programs whereby the applicable sales charge may be waived or reduced. You or your financial intermediary must inform MFSC upon purchasing fund shares of your intention to invest in a fund under one of the programs below. You can provide this information in your account application or through a separate document provided by your financial intermediary.

	INVESTMENTS ELIGIBLE FOR:
Program	WAIVED INITIAL SALES CHARGE	REDUCED INITIAL SALES CHARGE	WAIVED CDSC
Letter of Intent		X
Right of Accumulation		X
Automatic Exchange Plan	X*
Exchange Privilege	X*
Systematic Withdrawal Plan			X**
Distribution Reinvestment	X
Distribution Investment Program	X
Reinstatement Privilege	X
Other Sales Charge Waivers	X		X

* Investments under the Automatic Exchange Plan or certain other exchanges may be subject to a sales charge in certain cases.

** Limited for Class A, Class B and Class C shares.

· Letter Of Intent (LOI). You may pay a reduced or no initial sales charge on purchases of Class A shares if you intend to invest a specific dollar amount, based on the gross amount of your investment (including the amount of any sales charge paid), including investments through any linked accounts in any class of any MFS fund within a 13-month period (36 months for a $1 million commitment). Distributions reinvested in additional shares of the fund or distributions from other MFS funds automatically invested in shares of the fund will not apply toward the satisfaction of the LOI.

For each purchase you make under the LOI you will pay the initial sales charge rate applicable to the total amount you intended to purchase. If, however, you do not purchase the intended amount within the relevant time period, your account will be adjusted by redemption of the amount of shares needed to pay the higher initial sales charge level for the amount actually purchased.

To establish an LOI, complete the Letter of Intent section of your account application or service application. In order to benefit from the LOI, you or your financial intermediary must inform MFSC that the LOI is in effect each time shares of a fund are purchased.

· Right Of Accumulation (ROA). Under the ROA, you may pay a reduced or no initial sales charge on purchases of Class A shares by aggregating the total dollar amount of your investment with your existing investments or any linked accounts invested in MFS funds, based on the current maximum public offering price of the funds. For example, you will pay a sales charge on your current purchase at the rate applicable to the total value of all eligible accounts based on the sales charge schedule above.

· Linking Accounts For LOI and ROA. For purposes of obtaining reduced sales charges under the LOI and ROA, you may combine the value of your accounts

MFS Absolute Return Fund

with those of your spouse (or legal equivalent under applicable state law) and your children under the age of 21.

Eligible accounts that you may link under an LOI and ROA are:

· Individual accounts;

· Joint accounts;

· Trust accounts of which you, your spouse (or legal equivalent under applicable state law), or child under the age of 21 is the grantor;

· MFS 529 College Savings Plan accounts;

· Certain single-participant retirement plan accounts;

· Certain Individual Retirement Accounts;

· Uniform Gifts/Transfers to Minor Acts accounts; and

· Accounts held in the name of your financial intermediary on your behalf.

In order to link such accounts, the broker/dealer at the time of your current purchase for an ROA or at the time of the establishment of an LOI must be the broker/dealer (or the clearing broker/dealer for your broker/dealer so long as your account is not aggregated by the clearing broker/dealer with other accounts) for any additional accounts to be linked. MFS fund shares held as follows cannot be combined for purposes of an LOI or ROA:

· Shares held indirectly through financial intermediaries other than the broker/dealer for your current purchase (for example, shares held in a different broker/dealer’s brokerage account or with a bank, an insurance company separate account or an investment adviser); or

· Shares held directly in a MFS fund account on which the broker/dealer is different than the broker/dealer for your current purchase for an ROA or is different than the broker/dealer at the time of the establishment of the LOI.

It is your responsibility to inform the broker/dealer for each current purchase of any accounts held with the MFS funds that you believe are eligible to be linked under an LOI or an ROA. If you have not designated a broker/dealer, you should inform MFSC directly of any accounts held with the MFS funds that you believe are eligible to be linked under an LOI or an ROA. You should provide your financial intermediary (or MFSC if you have not designated a broker/dealer) with certain supporting information at the time of each purchase regarding accounts held with the MFS funds that are eligible to be combined for purposes of an LOI or ROA. Such information may include shareholder identification numbers or applicable account numbers or account statements. Your financial intermediary is responsible for taking into account this information about accounts eligible to be combined when transmitting your purchase order to the fund.

Special Note for ROA eligible accounts linked prior to May 1, 2006. Any ROA eligible accounts linked prior to May 1, 2006, will remain linked to the extent the broker/dealer information for such accounts is not modified. In the event you change the broker/dealer for any such account, your accounts will no longer be eligible to be linked under an ROA. In addition, with respect to ROA eligible accounts linked prior to May 1, 2006, you will not be able to link additional accounts to the extent they do not meet the criteria discussed above.

· Automatic Exchange Plan (not available for Class R1, Class R2, Class R3, Class R4, and Class R6 shares). If you have a balance of at least $2,000 in your account in the fund, you may participate in the automatic exchange plan, a dollar-cost averaging program. This plan permits you to make automatic periodic exchanges from your account in the fund for shares of the same class of other MFS funds. Exchanges will generally be made at net asset value without any sales charges. Shares otherwise subject to a CDSC will not be charged a CDSC in an exchange. Shares will retain the CDSC schedule in effect based upon a pro rata share of the CDSC from the exchanged fund and the original purchase date of the shares subject to the CDSC.

· Systematic Withdrawal Plan. If you have a balance of at least $5,000 in your account in the fund, you may elect to receive (or designate someone else to receive) regular periodic payments (of at least $50 if by check) through an automatic redemption of Class A, Class B, Class C, or Class I shares. For Class A, Class B, and Class C shares, you may incur a CDSC when Class A, Class B, and Class C shares are redeemed under the plan (or plans if more than one plan is established) if greater than 10% of the value of your account is withdrawn under the plan(s) in any one year (determined at the time of your first withdrawal under the plan(s), or January 4, 2016, with respect to Class A shares, January 3, 2007, with respect to Class B shares, or January 2, 2008, with respect to Class C shares, whichever is later). The applicable CDSC will be prorated across all of your payments taken in the one year period.

· Distribution Reinvestment. You may automatically reinvest dividend and capital gain distributions in the same fund without paying an initial sales charge.

· Distribution Investment Program. You may automatically reinvest dividend and capital gain distributions from Class A, Class B, and Class C shares into the same class of another MFS fund without paying a CDSC or an initial sales charge.

· Reinstatement Privilege. With respect to Class A, Class B and Class C shares, after you have redeemed fund shares, you have a one-time right per fund per registration to reinvest the proceeds in the fund within 90 days of the redemption without paying a sales charge. Proceeds can only be reinvested in the same class of the same fund under the same account registration, except proceeds from a Class B share redemption can only be reinvested into Class A shares.

Any CDSC paid upon the redemption of Class A shares or Class C shares will be credited to your account, and your new Class A shares or Class C shares will be subject to a CDSC according to the CDSC schedule applicable to your original shares.

Any CDSC paid upon the redemption of Class B shares will not be credited to your account.

MFS Absolute Return Fund

In order to benefit from the reinstatement privilege, you or your financial intermediary must inform MFSC that the reinstatement privilege is in effect each time shares of the fund are purchased under this privilege.

Calculation Of CDSC. As discussed above, certain investments in Class A, Class B, and Class C shares are subject to a CDSC. For purposes of calculating the CDSC, purchases made on any day during a calendar month will age one month at the close of business on the last day of that month, and at the close of business on the last day of each subsequent month. The CDSC is based on the original purchase cost or the current market value of the shares being sold, whichever is less. For purposes of determining the CDSC, if you sell only some of your shares, shares not subject to a CDSC are sold first, followed by shares held the longest.

Shares acquired through reinvestment of distributions are not subject to a CDSC.

Distribution and Service Fees

The fund has adopted a plan in accordance with Rule 12b-1 under the Investment Company Act of 1940, as amended (the “Distribution Plan”). Under the Distribution Plan, the fund pays distribution and/or service fees to MFD to support the sale and distribution of Class A, Class B, Class C, Class R1, Class R2, and Class R3 shares, and/or shareholder servicing and account maintenance activities. These distribution and/or service fees equal on an annual basis up to the following maximum percentages of average daily net assets of the class:

CLASS	MAXIMUM DISTRIBUTION FEE		MAXIMUM SERVICE FEE		MAXIMUM TOTAL DISTRIBUTION AND SERVICE FEE
Class A	0.00	%	0.25	%	0.25	%
Class B	0.75	%	0.25	%	1.00	%
Class C	0.75	%	0.25	%	1.00	%
Class R1	0.75	%	0.25	%	1.00	%
Class R2	0.25	%	0.25	%	0.50	%
Class R3	0.00	%	0.25	%	0.25	%

These fees are paid out of fund assets of the applicable class of shares. Because these fees are an ongoing expense of the fund, they increase the cost of your investment over time and may cost you more than other types of sales charges.

The fund has not adopted a Rule 12b-1 plan with respect to its Class I, Class R4, or Class R6 shares.

Financial Intermediary Compensation

The term “financial intermediary” refers to any broker/dealer, bank (including bank trust departments), registered investment adviser, financial planner, retirement plan administrator, third-party administrator, insurance company, and any other institution having a selling, administration, or any similar agreement with MFD, MFS, or any of their affiliates.

Financial intermediaries receive various forms of compensation in connection with the sale of shares of a fund and/or the servicing of shareholder accounts. Financial intermediaries may receive such compensation (i) in the form of up-front commissions and ongoing asset-based compensation paid by MFD based on sales charges received and expected to be received by MFD from shareholders and Distribution Plan distribution and service payments received by MFD from the fund, (ii) in the form of shareholder servicing payments paid by MFD and/or one or more of its affiliates (for purposes of this section only, collectively, “MFD”) based on the receipt of such payments by MFD from the fund, and (iii) in the form of payments paid by MFD from MFD’s own additional resources.

Financial intermediaries may receive up-front commissions of up to the following percentage amounts for sales of the following share classes:

SHARE CLASS	UP FRONT COMMISSION AS A PERCENTAGE OF OFFERING PRICE
Class A	4.25	%
Class B	3.75	%
Class C	1.00	%

In addition, financial intermediaries may receive payments from MFD from MFD’s own additional resources as incentives to market the MFS funds, to cooperate with MFD’s promotional efforts and/or in recognition of their marketing, administrative services, and/or transaction processing support. This compensation from MFD is not reflected in the fees and expenses listed in the fee table section of the fund’s prospectus. MFD compensates financial intermediaries based on criteria established by MFD from time to time that consider, among other factors, the distribution potential of the financial intermediary, the types of products and programs offered by the financial intermediary, the level and/or type of marketing and administrative support provided by the financial intermediary, the level of assets attributable to and/or sales by the financial intermediary and the quality of the overall relationship with the financial intermediary.

These additional payments by MFD may take the form of payments to financial intermediaries that provide marketing support and administrative services to MFD with respect to fund shares sold or held through the financial intermediary’s distribution network and/or through programs such as retirement programs, qualified tuition programs, fund supermarkets, fee-based advisory or wrap fee programs, bank trust programs, and insurance (e.g., individual or group annuity) programs. MFD may also make payments to financial intermediaries to help offset the cost associated with client account maintenance support, statement preparation, and transaction processing. To the extent permitted by SEC (U.S. Securities and Exchange Commission) and FINRA (Financial Industry Regulatory Authority) rules and other applicable laws and regulations, MFD may make other payments or allow other promotional incentives or payments to financial intermediaries.

The types of payments described above are not exclusive and such payments can be significant to the financial intermediary. In addition, the compensation that financial intermediaries receive may vary by class of shares sold and among financial intermediaries. Depending upon the arrangements in place at any particular time, financial intermediaries may have a financial incentive to recommend a particular fund or share class.

You can find further details in the SAI about the payments made by MFD and the services provided by financial intermediaries. Financial intermediaries may charge you additional fees and/or commissions other than those disclosed in this prospectus. You can ask your financial intermediary for information about any payments it receives from MFD and any services it provides, as well as about fees and/or commissions it charges. Financial intermediaries that sell fund shares may also act as a broker/dealer in connection with a MFS fund’s purchase or sale of portfolio securities. However, the

MFS Absolute Return Fund

fund and MFS do not consider financial intermediaries’ sales of shares of an MFS fund as a factor when choosing broker/dealers to effect portfolio transactions for the MFS funds.

How To Purchase, Redeem, and Exchange Shares

You may purchase, redeem, and exchange shares of the fund in the manner described below. The fund is generally only available to U.S. residents with a valid U.S. tax identification number (and to certain other qualified investors). If you buy or sell shares of a fund through a retirement account, 529 plan, or financial intermediary, the procedures for buying, selling, and exchanging shares of the fund and the features, policies and fees may differ from those discussed in this prospectus. Investment minimums may be waived or reduced for certain types of investors and investments and your financial intermediary may have additional minimums.

How to Purchase Shares

Your shares will be bought at the offering price (the net asset value per share plus any applicable initial sales charge) next calculated after your purchase order is received in proper form. A purchase of shares by an MFS fund is treated as received by the fund when the MFS fund receives the purchase order in proper form to be allocated to the fund. Your financial intermediary is responsible for transmitting your purchase order to the fund in proper form and in a timely manner. MFSC reserves the right to reject any purchase order that is not in proper form. The specific requirements for proper form depend on the type of account and transaction and the method of purchase; contact MFSC if you have questions about your particular circumstances. Certain restrictions apply to the use of a transfer on death registration. You or your financial intermediary should contact MFSC to obtain a Transfer on Death registration form and for information regarding MFSC’s other requirements for transfer on death registrations. If payment for a purchase order is not received by the time required under applicable law, your purchase order may be cancelled and your financial intermediary could be liable for any costs or losses.

The fund may reject for any reason, or cancel as permitted or required by law, any purchase orders. The fund may stop offering shares completely, or may offer shares only on a limited basis, for a period of time or permanently.

The fund is required by law to obtain from you certain personal information that will be used to verify your identity. If you do not provide the information, the fund will not be able to open your account. The fund must also take certain steps to verify that the account information you provide is correct.

Class A, Class B, and Class C Shares. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

Purchases of Class B shares are subject to a total account value limitation at the time of purchase of $99,999, and purchases of Class C shares are subject to a total account value limitation at the time of purchase of $999,999. If your existing accounts for all share classes held with the MFS funds have a total value equal to $99,999 for Class B share purchases or $999,999 for Class C share purchases, you will not be able to purchase Class B or Class C shares, as applicable. For the purpose of determining your total account value, existing accounts for all share classes held with the MFS funds that are linked under a LOI or ROA will be included.

The fund or its agents may at their discretion accept a purchase request for Class B shares or Class C shares that would otherwise exceed the total account value limitation of $99,999 and $999,999, respectively, under certain circumstances, including purchases by certain types of group or sponsored retirement plans.

As of October 1, 2016, the above two paragraphs are restated as follows:

Purchases of Class B shares are subject to a total account value limitation at the time of purchase of $99,999, and purchases of Class C shares are subject to a total account value limitation at the time of purchase of $499,999. If your existing accounts for all share classes held with the MFS funds have a total value equal to $99,999 for Class B share purchases or $499,999 for Class C share purchases, you will not be able to purchase Class B or Class C shares, as applicable. For the purpose of determining your total account value, existing accounts for all share classes held with the MFS funds that are linked under a LOI or ROA will be included.

The fund or its agents may at their discretion accept a purchase request for Class B shares or Class C shares that would otherwise exceed the total account value limitation of $99,999 and $499,999, respectively, under certain circumstances, including purchases by certain types of group or sponsored retirement plans.

Class I Shares. You can establish an account through your MFD representative, by having your financial intermediary process your purchase, or by contacting MFSC directly.

Class R1, Class R2, Class R3, Class R4, and Class R6 Shares. You can establish an account through your financial intermediary or by contacting MFSC directly. For Class R6 investors, you can also establish your account through your MFD representative.

Additional Purchases

You may purchase additional shares through your financial intermediary or MFSC.

· Additional Purchases Directly Through MFSC.

· Mail. You may purchase additional shares by mailing a check with your investment instructions to MFSC.

· Telephone. You may purchase additional shares by phone from your pre-designated bank account. You must elect this privilege on your account application or service application. Purchases via telephone are not available for certain types of accounts.

· Internet. You may purchase additional shares from a pre-designated bank account via the Internet at mfs.com (MFS Access). You must elect this privilege on your account application or service application and establish a password on MFS Access to use this service. Purchases via the Internet are not available for Class R1, Class R2, Class R3, Class R4, and Class R6 shares, and certain types of accounts.

· Wire. To purchase additional shares by wire, call MFSC for instructions.

· Automatic Investment Plan. You may purchase additional shares by automatically investing a designated amount from your checking or savings account on any day of the month. You must elect this privilege on your account application or service application.

· Additional Purchases Through Your Financial Intermediary. You can have your financial intermediary purchase shares on your behalf. Your

MFS Absolute Return Fund

financial intermediary will be responsible for furnishing all necessary documents to MFSC and may charge you for this service.

How to Redeem Shares

Your shares will be sold at the net asset value per share next calculated after your redemption order is received in proper form, minus any applicable CDSC and/or other fees. A redemption of shares by an MFS fund is treated as received by the fund when the MFS fund receives the redemption order in proper form to be allocated to the fund. Your financial intermediary is responsible for transmitting your redemption order to the fund in proper form and in a timely manner. MFSC reserves the right to reject any redemption request that is not in proper form. The specific requirements for proper form depend on the type of account and transaction and the method of redemption; contact MFSC if you have questions about your particular circumstances. A redemption order in an amount less than or equal to the value of your account (other than an exchange) is considered to be in proper form only with respect to shares in your account for which payment has been received and collected. A new redemption order must be submitted if you wish to redeem your shares for which payment had not been received and collected at the time the prior redemption order was received by the fund. Receiving and collecting payment can take up to seven business days after a purchase. In certain circumstances, you will need to have your signature guaranteed and/or submit additional documentation to redeem your shares. In general, no signature guarantee is required for a redemption order for up to $100,000 that is signed by all owners or fiduciaries identified in the account registration, paid as registered, and mailed to the address of record. However, if you have changed your address of record within 30 days of your redemption order, a signature guarantee may be required.

The fund normally sends out your redemption proceeds within seven days after your request is received in proper form. Under unusual circumstances, such as when the New York Stock Exchange (the “NYSE”) is closed, trading on the NYSE is restricted, or as permitted by the SEC, the fund may suspend redemptions or postpone payment for more than seven days.

You may redeem your shares either by having your financial intermediary process your redemption or by contacting MFSC directly.

Redeeming Directly Through MFSC.

· Mail. To redeem shares by mail, you can send a letter, or the applicable redemption form, to MFSC with the name of the fund, your account number, and the number of shares or dollar amount to be redeemed. MFSC currently charges a fee to send your proceeds via overnight mail.

· Telephone. If a signature guarantee is not required, you can call MFSC to have shares redeemed from your account and proceeds mailed to the address of record on the account. MFSC currently charges a fee to send your proceeds via overnight mail. You can also call MFSC to have shares redeemed from your account and the proceeds sent directly to a pre-designated bank account. You must elect this privilege on your account application or service application if you wish to have proceeds sent to your bank account. Telephone redemptions are not available for certain types of accounts.

· Internet. If a signature guarantee is not required, you can have shares redeemed from your account via the Internet at mfs.com (MFS Access) and the proceeds mailed to the address of record on the account. You can also have shares redeemed from your account via MFS Access and the proceeds sent directly to a pre-designated bank account. You must elect this privilege on your account application or service application and establish a password on MFS Access to use this service. Redemptions via the Internet are not available for Class R1, Class R2, Class R3, Class R4, and Class R6 shares, and certain types of accounts.

· Systematic Withdrawal Plan. For Class A, Class B, Class C, or Class I shares, you may elect to automatically receive (or designate someone else to receive) regular periodic payments through an automatic redemption of such classes. Please contact MFSC for details.

Redeeming Through Your Financial Intermediary. You can have your financial intermediary process a redemption on your behalf. Your financial intermediary will be responsible for furnishing all necessary documents to MFSC and may charge you for this service.

Signature Guarantee/Additional Documentation. If a signature guarantee is required, your signature may be guaranteed by an eligible bank, broker/dealer, credit union, national securities exchange, registered securities association, clearing agency, or savings association. MFSC may require additional documentation for certain types of registrations and under certain circumstances. Signature guarantees and this additional documentation shall be accepted in accordance with policies established by MFSC, and MFSC may, at its discretion, make certain exceptions to these requirements. Please contact MFSC with any questions and for the requirements for your particular situation.

Share Certificates. If certificates are outstanding for your shares, you may only redeem such shares by mailing the certificates to MFSC. Telephone, electronic, and systematic withdrawal plan redemptions and checkwriting are not available if certificates are outstanding for your shares.

Redemptions In Kind. If, during any 90-day period, you redeem shares in an amount greater than the lesser of $250,000 or 1% of fund net assets, the fund may pay the redemption amount above such threshold by a distribution in kind of portfolio securities (redemption in kind). In the event that the fund makes a redemption in kind, you should expect to incur brokerage and other transaction charges when converting the securities to cash, and the securities will likely increase or decrease in value before you sell them.

Involuntary Redemptions. Because it is costly to maintain small accounts, the MFS funds have reserved the right to redeem your Class A, Class B, or Class C shares without your permission when your account contains less than $500 for any reason, including market fluctuation. Before the fund makes such a redemption, you will be notified and given 60 days to increase your investment to at least $500. Certain accounts are not subject to these provisions. Any applicable CDSC will be waived for shares redeemed due to the small size of a shareholder’s account.

In addition, the MFS funds have reserved the right to redeem your shares without your permission in cases of threatening conduct or suspicious, fraudulent, or illegal activity. Any applicable CDSC will be assessed upon redemption of your shares.

How to Exchange Shares

An exchange involves the redemption of shares of one fund and the purchase of shares of another fund.

Exchange Privilege. You can exchange your shares for shares of the same class of most other MFS funds by having your financial

MFS Absolute Return Fund

intermediary process your exchange request or by contacting MFSC directly.

You can exchange your Class A shares and your Class I shares for shares of the MFS U.S. Government Money Market Fund, if available, according to the terms of such fund’s prospectus.

Shares otherwise subject to a CDSC will not be charged a CDSC in an exchange. Shares will retain the CDSC schedule in effect based upon a pro rata share of the CDSC from the exchanged fund and the original purchase date of the shares subject to the CDSC.

You should read the prospectus of the MFS fund into which you are exchanging and consider the differences in investment objectives, policies, and risks, and in fees and expenses, before making an exchange. The exchange privilege may be changed or discontinued at any time, and all exchanges are subject to certain limitations and the MFS funds’ policies concerning disruptive trading practices, which are designed to protect the funds and their shareholders from the harmful effects of frequent trading.

The MFS funds allow certain financial intermediaries to place exchange orders on behalf of a group of their discretionary investment advisory clients (“group exchange orders”). As with any exchange request, the funds and their agents reserve the right to reject any group exchange order, and the funds’ agents will generally reject any group exchange order received by the funds or their agents after 1 p.m., Eastern time. In addition, MFD has agreements with certain financial intermediaries which set forth the terms and conditions under which group exchange orders may be placed by these financial intermediaries. These conditions may be more restrictive than those applicable to individual exchange orders, and may include the requirement to provide the funds or their agents with advance notice of group exchange orders.

Other Considerations

Disruptive Trading

General Purchase and Exchange Limitation Policy . The MFS funds reserve the right to restrict, reject, or cancel, without any prior notice, any purchase or exchange order, including transactions believed to represent frequent or other disruptive trading activity. In the event that MFSC rejects or cancels an exchange request, neither the redemption nor the purchase side of the exchange will be processed. Each MFS fund reserves the right to delay for one business day the processing of exchange requests in the event that, in MFSC’s judgment, in consultation with MFS, as appropriate, such delay would be in the fund’s best interest, in which case both the redemption and purchase side of the exchange will receive the funds’ net asset values at the conclusion of the delay period.

Disruptive Trading Risks. To the extent that the MFS funds or their agents are unable to curtail disruptive trading practices in a fund (e.g., frequent trading) or to the extent there are large or frequent redemptions in a fund, these purchases and/or redemptions can interfere with the efficient management of the fund’s portfolio, may result in increased transaction and administrative costs, and may adversely impact the fund’s performance.

In addition, to the extent that the fund invests in foreign securities, the interests of long-term shareholders may be diluted as a result of time-zone arbitrage, a short-term trading practice that seeks to exploit changes in the value of the fund’s investments that result from events occurring after the close of the foreign markets on which the investments trade, but prior to the time the fund determines its net asset value. The fund’s use of fair valuation can serve to reduce arbitrage opportunities available to short-term traders, but there is no assurance that the fund’s fair valuation policies and procedures will prevent dilution of the fund’s net asset value by short-term traders.

To the extent that the fund invests in securities that trade infrequently or are difficult to value, such as the securities of smaller companies, high yield debt instruments, and floating rate loans, the interests of long-term shareholders may be diluted as a result of price arbitrage, a short-term trading strategy that seeks to exploit perceived pricing inefficiencies in the fund’s investments. Such short-term trading strategies may interfere with efficient management of the fund’s portfolio to a greater degree than funds that invest in more frequently traded or liquid securities, in part because the fund may have difficulty selling these portfolio securities at advantageous times or prices to satisfy large and/or frequent redemption requests. Any successful price arbitrage may also cause dilution in the value of fund shares held by other shareholders.

Frequent Trading. The fund is not intended to serve as a vehicle for frequent trading. The Board of Trustees of the fund has adopted the purchase and exchange limitation policy described below, which it believes is reasonably designed to discourage frequent fund share transactions. MFSC seeks to monitor and enforce this policy, subject to oversight by the Board of Trustees. The fund may alter its policies at any time without notice to shareholders.

MFSC will generally restrict, reject or cancel purchase and exchange orders into the fund if MFSC determines that an accountholder has made two exchanges, each in an amount of $15,000 or more, out of an account in the fund during a calendar quarter (“two exchange limit”). This policy does not apply to MFS money market funds or to exchanges initiated by another MFS fund that invests in the fund, a retirement plan trustee or sponsor rather than by a plan participant, and other similar non-discretionary exchanges (e.g., in connection with fund mergers/acquisitions/liquidations). MFSC may make exceptions to this policy if, in its judgment, the transaction does not represent frequent trading activity, such as purchases made through systematic purchase plans (but not systematic exchange plans), payroll contributions, or distribution investment programs. In applying this policy, MFSC considers the information available to it at the time and reserves the right to consider trading effected through multiple accounts that are under common ownership, control, or influence to be trading out of a single account.

Exchanges made on the same day in the same account are aggregated for purposes of counting the number and dollar amount of exchanges made by the accountholder (e.g., an accountholder who on the same day exchanges $16,000 from the fund into two other MFS funds, by exchanging $8,000 into each of the two MFS funds, will be viewed as having made one exchange transaction exceeding $15,000 in value).

Omnibus accounts, in which shares are held in the name of a financial intermediary on behalf of multiple underlying shareholders, are a common form of holding shares among certain financial intermediaries such as brokers, retirement and 529 plans, investment advisers, and insurance companies.

Financial intermediaries are required to reject any purchase or exchange orders in the fund if they believe the orders represent frequent trading activity unless they notify MFSC or an affiliate in writing that they do not monitor for frequent trading (“Waived Financial Intermediary”). With respect to Waived Financial Intermediaries, MFSC will take action reasonably designed to discourage frequent trading that is not in the best interests of the fund by the customers of such Waived Financial Intermediary, including requesting underlying shareholder account data more frequently than from other financial intermediaries.

With respect to omnibus accounts that provide MFSC with underlying shareholder data daily, MFSC will apply the two exchange limit directly to underlying shareholders. For all other

MFS Absolute Return Fund

accounts which MFSC determines are omnibus accounts, MFSC will apply the two exchange limit to the omnibus account itself. Applying the two exchange limit to the omnibus account itself will not necessarily detect violations of the two exchange limit by underlying shareholders. If the financial intermediary associated with an omnibus account that has triggered the two exchange limit demonstrates to MFSC, as determined in MFSC’s sole discretion, that no single underlying shareholder triggered the two exchange limit, then MFSC will remove any restrictions, rejections or cancellations imposed on the account. If the financial intermediary demonstrates to MFSC that a single underlying shareholder triggered the two exchange limit and that the financial intermediary itself will apply applicable restrictions, rejections or cancellations to that underlying shareholder, MFSC will likewise remove any restrictions, rejections or cancellations imposed on the omnibus account. Otherwise, MFSC will continue to apply the two exchange limit to the omnibus account.

Certain financial intermediaries may use procedures to restrict frequent trading by their customers who invest in the fund while others may not employ any procedures to restrict frequent trading. Such procedures, if any, may be less restrictive than the fund’s purchase and exchange limitation policy, may permit transactions not permitted by the fund’s purchase and exchange limitation policy, including transactions in excess of the two exchange limit, and/or may prohibit transactions not subject to the fund’s purchase and exchange limitation policy. You should consult your financial intermediary about any restrictions it imposes on frequent trading.

There is no assurance that MFSC will be able to detect or prevent frequent trading. Shareholders seeking to engage in frequent trading practices may deploy a variety of strategies to avoid detection, and MFSC is generally not able to identify trading by a particular underlying shareholder within an omnibus account, which makes it difficult or impossible to determine if a particular underlying shareholder is engaged in frequent trading.

MFSC reviews trading activity to detect trading activity that may be indicative of frequent trading based on its internal parameters for detecting frequent trading, including reviewing transactions (including exchanges) that exceed a certain dollar amount, transactions involving similar dollar amounts, or transactions that occur close in time to other transactions in the same account or in multiple accounts that are under common ownership or influence. Any or all of these parameters (including those not listed) may change at any time. MFSC does not review the trading activity by other MFS funds that invest in the fund. If MFSC detects suspicious trading activity at the omnibus account level, it will contact the financial intermediary to request underlying shareholder level activity to determine whether there is underlying shareholder level frequent trading. However, the underlying shareholder data received may not reflect information about the ultimate underlying shareholders because there may be multiple layers of omnibus accounts. If frequent trading is identified, MFSC will take appropriate action, such as requesting the financial intermediary to prohibit purchases into the account by the underlying shareholder, requiring purchases by the underlying shareholder to be submitted only by mail, or prohibiting purchases from the financial intermediary.

MFSC’s ability to monitor and deter frequent trading in omnibus accounts depends on, among other factors, the frequency with which MFSC requests underlying shareholder account data from omnibus accounts. MFSC expects to request underlying shareholder data based on its assessment of the likelihood of frequent trading by underlying shareholders among other factors. MFSC expects to request underlying shareholder data from Waived Financial Intermediaries more frequently than from other financial intermediaries. There is no assurance that MFSC will request data with sufficient frequency to detect or prevent frequent trading in omnibus accounts effectively.

Unauthorized Transactions. MFS will not be responsible for losses that result from unauthorized transactions unless MFSC does not follow procedures reasonably designed to verify your identity. If an account has more than one owner or authorized person, MFSC will accept telephone and online instructions from any one owner or authorized person, except MFSC will require instructions for a redemption from all trustees of trust accounts registered with multiple trustees. It is important that you contact MFSC immediately about any transactions made through MFSC you believe to be unauthorized.

Ability to Contact MFSC. Certain methods of contacting MFSC, such as by mail, telephone, or electronically, may be unavailable or delayed (for example, after natural disasters, during periods of significant/major political, social, or economic instability, or in the event of a cybersecurity incident).

Reservation of Other Rights. In addition to the rights expressly stated elsewhere in this prospectus, subject to applicable rules, laws, and regulations, MFSC reserves the right to: 1) alter, add, or discontinue any conditions of purchase, redemption, service, or privilege at any time without notice; 2) freeze any account or suspend account services when MFSC has received reasonable notice (written or otherwise) of a dispute between registered or beneficial account owners or when MFSC believes a fraudulent transaction may occur or has occurred; and 3) change, impose, discontinue, or waive any fee it charges.

Anti-Money Laundering Restrictions. Federal law requires the fund to implement policies and procedures reasonably designed to prevent, detect and report money laundering and other illegal activity. The fund, consistent with applicable federal law, may redeem your shares and close your account; suspend, restrict or cancel purchase and redemption orders; process redemption requests and withhold your proceeds; and take other action if it is unable to verify your identity within a reasonable time or conduct required due diligence on your account or as otherwise permitted by its anti-money laundering policies and procedures. Any applicable CDSC will be assessed upon redemption of your shares.

Confirmations in Quarterly Statements. Transactions made under certain periodic investment and withdrawal programs (including reinvestment plans) will be confirmed on quarterly account statements.

Other Information

Valuation

The price of each class of the fund’s shares is based on its net asset value. The net asset value of each class of shares is determined each day the NYSE is open for trading as of the close of regular trading on the NYSE (generally 4:00 p.m. Eastern time). However, net asset value may be calculated earlier in emergency situations or as otherwise permitted by the SEC. Net asset value per share is computed by dividing the net assets allocated to each share class by the number of shares outstanding for that class. On days when the NYSE is closed (such as weekends and holidays), net asset value is not calculated, and the fund does not transact purchase and redemption orders. To the extent the fund’s assets are traded in other markets on days when the fund does not price its shares, the value of the fund’s assets will likely change when you will not be able to purchase or redeem shares of the fund.

To determine net asset value, the fund’s investments for which reliable market quotations are readily available are valued at market

MFS Absolute Return Fund

value, and funds in which the fund invests are generally valued at their net asset value per share. Certain short term debt instruments may be valued at amortized cost.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to MFS pursuant to valuation policies and procedures approved by the Board of Trustees. If MFS determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by MFS in accordance with such procedures under the oversight of the Board of Trustees.

Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. These valuations can be based on both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data.

In addition, investments may be valued at fair value if MFS determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as a foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. MFS generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Distributions

The fund intends to declare and pay any dividends to shareholders at least monthly.

Any capital gains are distributed at least annually.

Distribution Options

The following distribution options are generally available:

· Dividend and capital gain distributions automatically reinvested in additional shares (this option will be assigned if no other option is specified) ;

· Dividend distributions in cash; capital gain distributions automatically reinvested in additional shares;

· Dividend and capital gain distributions in cash; or

· Dividend and capital gain distributions automatically reinvested into the same class of shares of another MFS Fund.

Not all options are available for every class or every account.

Dividends and capital gain distributions for Class R1, Class R2, Class R3, Class R4, and Class R6 shares automatically will be reinvested in additional shares of the fund.

The distribution option for accounts with dividend distributions of less than $10 generally will be changed to reinvestment in additional shares of the fund. If you have elected to receive distributions in cash, and the postal service is unable to deliver checks to your address of record, or you do not respond to mailings from MFSC with regard to uncashed distribution checks, your distribution option may be converted to having all distributions reinvested in additional shares. You should contact MFSC to change your distribution option, and your request to do so must be received by MFSC before the record date for a distribution in order to be effective for that distribution. No interest will accrue on amounts represented by uncashed distribution checks.

Tax Considerations

The following discussion is very general. You are urged to consult your tax adviser regarding the effect that an investment in the fund will have on your particular tax situation, including possible foreign, state, and local taxes. Also, this discussion does not apply to shares of the fund held through tax-advantaged retirement plans or by shareholders that are not “U.S. persons” under the Internal Revenue Code of 1986, as amended.

The fund expects to distribute substantially all of its income and gains annually. Distributions from the fund are taxable whether you receive them in cash or reinvest them in additional shares. If you buy shares when the fund has realized but not yet distributed ordinary income or capital gains, you will pay full price for the shares and then receive a portion back as a taxable distribution.

Any gain resulting from the redemption, sale, or exchange of your shares will generally also be subject to tax.

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 or is deemed to have owned the investments that generated them, rather than how long you have owned your shares. Distributions of gains from the sale of investments that the fund owned for more than one year and that are properly reported by the fund as capital gain dividends will be treated as long-term capital gains includible in net capital gain and taxed to individuals at reduced rates. Distributions of gains from the sale of investments that the fund owned for one year or less will be taxable as ordinary income. If some or all of the fund’s income derives from “qualified dividend income” and if you are an individual who meets holding period and other requirements with respect to the fund’s shares, those distributions that are properly reported by the fund as derived from qualified dividend income are taxed to you at the reduced rates applicable to net capital gains. The fund does not expect a significant portion of fund distributions to be derived from qualified dividend income.

A 3.8% Medicare contribution tax is generally imposed on distributions paid by the fund (other than exempt-interest dividends, if any) and net gains recognized on the sale, redemption, exchange, or other taxable disposition of shares of the fund paid to certain individuals, estates and trusts to the extent their income exceeds certain threshold amounts.

The fund’s investments in derivatives may subject the fund to special tax rules that can affect the amount, timing or character of fund income and distributions to shareholders. The fund’s investments in certain debt instruments and derivatives may cause the fund to recognize income in excess of the cash generated by such instruments. Thus, the fund could be required at times to liquidate other investments in order to satisfy its distribution requirements.

MFS Absolute Return Fund

The fund’s investments in foreign securities may be subject to foreign withholding or other taxes, which will decrease the fund’s return on those securities. If the fund is eligible to elect to “pass through” to you foreign income taxes that it pays, and if the fund so elects, you will be required to include your share of those taxes in gross income as a distribution from the fund and you will be allowed to claim a credit (or a deduction, if you itemize deductions) for such amounts on your federal income tax return, subject to certain limitations. In addition, the fund’s investments in certain foreign securities (including fixed income securities and derivatives) denominated in foreign currencies may increase or accelerate the fund’s recognition of ordinary income and may affect the timing, amount, or character of the fund’s distributions.

The Form 1099 that is provided to you early each year details your distributions from the fund and how they are treated for federal tax purposes, and cost basis information for shares purchased on or after January 1, 2012, that you redeemed, sold, or exchanged. Our default method for calculating cost basis is average cost basis. More information about other cost basis methods and a cost basis selection/change form are available on mfs.com . If your account is held by your financial intermediary, you must contact your financial intermediary to obtain information about available cost basis methods and cost basis elections for your account.

Information about the Summary Prospectus, Prospectus, and SAI

The Summary Prospectus, Prospectus, and SAI for a fund provide information concerning the fund. The Summary Prospectus, Prospectus, and SAI are updated at least annually and any information provided in a Summary Prospectus, Prospectus, or SAI can be changed without a shareholder vote unless specifically stated otherwise. The Summary Prospectus, Prospectus, and the SAI are not contracts between the fund and its shareholders and do not give rise to any contractual rights or obligations or any shareholder rights other than any rights conferred explicitly by federal or state securities laws that may not be waived.

Provision of Financial Reports and Summary Prospectuses

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one paper copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

Additional Information on Fees and Expenses and Performance

Fees and Expenses

The annual fund operating expenses shown in “Fees and Expenses” are based on annualized expenses reported during the fund’s most recently completed fiscal year expressed as a percentage of a class’ average net assets during the period. Annual fund operating expenses have not been adjusted to reflect the fund’s current asset size. In general, annual fund operating expenses, expressed as a percentage of a class’ average net assets, increase as the fund’s assets decrease. Annual fund operating expenses will likely vary from year to year.

Performance Information

All performance information shown in the “Class A Bar Chart” and the “Performance Table” reflects any applicable fee reductions and waivers and expense reimbursements in effect during the periods shown; without these, the performance would have been lower.

From time to time, the fund may receive proceeds from litigation settlements, without which performance would be lower.

The fund commenced operations on March 30, 2011, with the offering of Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, and Class R4 shares, and subsequently offered Class R6 shares on October 1, 2012.

In the “Performance Table,” performance for Class R6 shares includes the performance of the fund’s Class I shares, adjusted to take into account differences in sales loads and class specific operating expenses (such as Rule 12b-1 fees), if any, for periods prior to their offering.

MFS Absolute Return Fund

Financial Highlights

The financial highlights are intended to help you understand a fund’s financial performance for the past five years (or, if shorter, the period of the fund’s and/or class’ operation). Certain information reflects financial results for a single fund share. The total returns in the financial highlights represent the rate by which an investor would have earned (or lost) on an investment in a fund (assuming reinvestment of all distributions) held for the entire period. This information has been audited by the fund’s independent registered public accounting firm, whose report, together with the fund’s financial statements, is included in the fund’s Annual Report to shareholders. The fund’s Annual Report is available upon request by contacting MFSC (please see back cover for address and telephone number). The fund’s independent registered public accounting firm is Deloitte & Touche LLP.

	Years ended 5/31
	2016			2015			2014			2013			2012

Class A
Net asset value, beginning of period	$	9.53		$	9.69		$	9.73		$	9.59		$	10.08
Income (loss) from investment operations
Net investment income (d)	$	0.04		$	0.02		$	0.02		$	0.04		$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	(0.26		)	(0.13		)	0.00		(w)	0.21			(0.37		)
Total from investment operations	$	(0.22	)	$	(0.11	)	$	0.02		$	0.25		$	(0.33	)
Less distributions declared to shareholders
From net investment income	$	(0.06	)	$	(0.05	)	$	(0.06	)	$	(0.11	)	$	(0.14	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.02		)
Total distributions declared to shareholders	$	(0.06	)	$	(0.05	)	$	(0.06	)	$	(0.11	)	$	(0.16	)
Net asset value, end of period (x)	$	9.25		$	9.53		$	9.69		$	9.73		$	9.59
Total return (%) (r)(s)(t)(x)	(2.31		)	(1.19		)	0.24			2.66			(3.31		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.45			1.47			1.45			1.51			1.35
Expenses after expense reductions (f)	1.14			1.14			1.14			1.15			1.15
Net investment income	0.41			0.16			0.23			0.40			0.43
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	2,710		$	2,809		$	3,846		$	3,348		$	3,197

	Years ended 5/31
	2016			2015			2014			2013			2012

Class B
Net asset value, beginning of period	$	9.47		$	9.66		$	9.72		$	9.59		$	10.08
Income (loss) from investment operation s
Net investment loss (d)	$	(0.03	)	$	(0.06	)	$	(0.05	)	$	(0.03	)	$	(0.03	)
Net realized and unrealized gain (loss) on investments and foreign currency	(0.25		)	(0.13		)	(0.01		)	0.21			(0.38		)
Total from investment operations	$	(0.28	)	$	(0.19	)	$	(0.06	)	$	0.18		$	(0.41	)
Less distributions declared to shareholders
From net investment income	$	—		$	—		$	(0.00	)(w)	$	(0.05	)	$	(0.07	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.01		)
Total distributions declared to shareholders	$	—		$	—		$	(0.00	)(w)	$	(0.05	)	$	(0.08	)
Net asset value, end of period (x)	$	9.19		$	9.47		$	9.66		$	9.72		$	9.59
Total return (%) (r)(s)(t)(x)	(2.96		)	(1.97		)	(0.58		)	1.85			(4.04		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	2.20			2.22			2.20			2.26			2.07
Expenses after expense reductions (f)	1.90			1.90			1.90			1.90			1.90
Net investment loss	(0.35		)	(0.59		)	(0.53		)	(0.34		)	(0.30		)
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	436		$	644		$	723		$	668		$	765

MFS Absolute Return Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class C
Net asset value, beginning of period	$	9.47		$	9.66		$	9.72		$	9.58		$	10.08
Income (loss) from investment operations
Net investment loss (d)	$	(0.03	)	$	(0.06	)	$	(0.05	)	$	(0.03	)	$	(0.03	)
Net realized and unrealized gain (loss) on investments and foreign currency	(0.26		)	(0.13		)	0.00		(w)	0.22			(0.38		)
Total from investment operations	$	(0.29	)	$	(0.19	)	$	(0.05	)	$	0.19		$	(0.41	)
Less distributions declared to shareholders
From net investment income	$	—		$	—		$	(0.01	)	$	(0.05	)	$	(0.08	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.01		)
Total distributions declared to shareholders	$	—		$	—		$	(0.01	)	$	(0.05	)	$	(0.09	)
Net asset value, end of period (x)	$	9.18		$	9.47		$	9.66		$	9.72		$	9.58
Total return (%) (r)(s)(t)(x)	(3.06		)	(1.97		)	(0.56		)	1.97			(4.11		)
Ratios (%) (to average net assets) and Supplemental data :
Expenses before expense reductions (f)	2.21			2.21			2.20			2.26			2.09
Expenses after expense reductions (f)	1.90			1.90			1.90			1.90			1.90
Net investment loss	(0.34		)	(0.59		)	(0.53		)	(0.34		)	(0.31		)
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	1,366		$	1,276		$	3,048		$	1,999		$	1,231

	Years ended 5/31
	2016			2015			2014			2013			2012

Class I
Net asset value, beginning of period	$	9.54		$	9.70		$	9.74		$	9.60		$	10.09
Income (loss) from investment operations
Net investment income (d)	$	0.06		$	0.04		$	0.05		$	0.08		$	0.06
Net realized and unrealized gain (loss) on investments and foreign currency	(0.25		)	(0.13		)	0.00		(w)	0.19			(0.37		)
Total from investment operations	$	(0.19	)	$	(0.09	)	$	0.05		$	0.27		$	(0.31	)
Less distributions declared to shareholders
From net investment income	$	(0.08	)	$	(0.07	)	$	(0.09	)	$	(0.13	)	$	(0.16	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.02		)
Total distributions declared to shareholders	$	(0.08	)	$	(0.07	)	$	(0.09	)	$	(0.13	)	$	(0.18	)
Net asset value, end of period (x)	$	9.27		$	9.54		$	9.70		$	9.74		$	9.60
Total return (%) (r)(s)(x)	(1.97		)	(0.94		)	0.48			2.86			(3.08		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.18			1.22			1.18			1.23			1.07
Expenses after expense reductions (f)	0.90			0.90			0.90			0.90			0.90
Net investment income	0.67			0.41			0.51			0.83			0.65
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	715		$	1,402		$	1,410		$	2,244		$	107,665

MFS Absolute Return Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R1
Net asset value, beginning of period	$	9.48		$	9.67		$	9.72		$	9.59		$	10.08
Income (loss) from investment operations
Net investment loss (d)	$	(0.03	)	$	(0.06	)	$	(0.05	)	$	(0.03	)	$	(0.03	)
Net realized and unrealized gain (loss) on investments and foreign currency	(0.25		)	(0.13		)	0.00		(w)	0.21			(0.38		)
Total from investment operations	$	(0.28	)	$	(0.19	)	$	(0.05	)	$	0.18		$	(0.41	)
Less distributions declared to shareholders
From net investment income	$	—		$	—		$	(0.00	)(w)	$	(0.05	)	$	(0.07	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.01		)
Total distributions declared to shareholders	$	—		$	—		$	(0.00	)(w)	$	(0.05	)	$	(0.08	)
Net asset value, end of period (x)	$	9.20		$	9.48		$	9.67		$	9.72		$	9.59
Total return (%) (r)(s)(x)	(2.95		)	(1.96		)	(0.48		)	1.84			(4.06		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	2.19			2.21			2.21			2.26			2.05
Expenses after expense reductions (f)	1.90			1.90			1.90			1.90			1.90
Net investment loss	(0.34		)	(0.59		)	(0.53		)	(0.35		)	(0.35		)
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	50		$	96		$	112		$	99		$	97

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R2
Net asset value, beginning of period	$	9.52		$	9.69		$	9.73		$	9.59		$	10.08
Income (loss) from investment operations
Net investment income (loss) (d)	$	0.01		$	(0.01	)	$	(0.00	)(w)	$	0.02		$	0.01
Net realized and unrealized gain (loss) on investments and foreign currency	(0.24		)	(0.14		)	0.00		(w)	0.21			(0.37		)
Total from investment operations	$	(0.23	)	$	(0.15	)	$	(0.00	)(w)	$	0.23		$	(0.36	)
Less distributions declared to shareholders
From net investment income	$	(0.04	)	$	(0.02	)	$	(0.04	)	$	(0.09	)	$	(0.11	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.02		)
Total distributions declared to shareholders	$	(0.04	)	$	(0.02	)	$	(0.04	)	$	(0.09	)	$	(0.13	)
Net asset value, end of period (x)	$	9.25		$	9.52		$	9.69		$	9.73		$	9.59
Total return (%) (r)(s)(x)	(2.47		)	(1.54		)	(0.02		)	2.41			(3.57		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.69			1.72			1.70			1.76			1.55
Expenses after expense reductions (f)	1.40			1.40			1.40			1.40			1.40
Net investment income (loss)	0.16			(0.09		)	(0.03		)	0.16			0.14
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	50		$	98		$	100		$	100		$	97

MFS Absolute Return Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R3
Net asset value, beginning of period	$	9.53		$	9.69		$	9.73		$	9.59		$	10.08
Income (loss) from investment operations
Net investment income (d)	$	0.04		$	0.02		$	0.02		$	0.04		$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	(0.26		)	(0.14		)	0.00		(w)	0.21			(0.37		)
Total from investment operations	$	(0.22	)	$	(0.12	)	$	0.02		$	0.25		$	(0.33	)
Less distributions declared to shareholders
From net investment income	$	(0.06	)	$	(0.04	)	$	(0.06	)	$	(0.11	)	$	(0.14	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.02		)
Total distributions declared to shareholders	$	(0.06	)	$	(0.04	)	$	(0.06	)	$	(0.11	)	$	(0.16	)
Net asset value, end of period (x)	$	9.25		$	9.53		$	9.69		$	9.73		$	9.59
Total return (%) (r)(s)(x)	(2.32		)	(1.19		)	0.23			2.65			(3.33		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.44			1.47			1.45			1.51			1.30
Expenses after expense reductions (f)	1.15			1.15			1.15			1.15			1.15
Net investment income	0.41			0.16			0.22			0.41			0.39
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	50		$	99		$	100		$	100		$	98

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R4
Net asset value, beginning of period	$	9.53		$	9.69		$	9.73		$	9.59		$	10.08
Income (loss) from investment operations
Net investment income (d)	$	0.06		$	0.04		$	0.05		$	0.06		$	0.06
Net realized and unrealized gain (loss) on investments and foreign currency	(0.26		)	(0.13		)	0.00		(w)	0.22			(0.37		)
Total from investment operations	$	(0.20	)	$	(0.09	)	$	0.05		$	0.28		$	(0.31	)
Less distributions declared to shareholders
From net investment income	$	(0.08	)	$	(0.07	)	$	(0.09	)	$	(0.14	)	$	(0.16	)
From net realized gain on investments	—			—			—			—			(0.00		)(w)
From tax return of capital	—			—			—			—			(0.02		)
Total distributions declared to shareholders	$	(0.08	)	$	(0.07	)	$	(0.09	)	$	(0.14	)	$	(0.18	)
Net asset value, end of period (x)	$	9.25		$	9.53		$	9.69		$	9.73		$	9.59
Total return (%) (r)(s)(x)	(2.07		)	(0.94		)	0.48			2.91			(3.08		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.19			1.22			1.20			1.26			1.05
Expenses after expense reductions (f)	0.90			0.90			0.90			0.90			0.90
Net investment income	0.66			0.41			0.47			0.66			0.64
Portfolio turnover	36			30			28			29			10
Net assets at end of period (000 omitted)	$	50		$	100		$	101		$	101		$	98

MFS Absolute Return Fund

	Years ended 5/31									Period ended 5/31
	2016			2015			2014			2013 (i)

Class R5
Net asset value, beginning of period	$	9.53		$	9.69		$	9.73		$	9.68
Income (loss) from investment operations
Net investment income (d)	$	0.07		$	0.05		$	0.05		$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	(0.26		)	(0.13		)	0.00		(w)	0.10		(g)
Total from investment operations	$	(0.19	)	$	(0.08	)	$	0.05		$	0.14
Less distributions declared to shareholders
From net investment income	$	(0.09	)	$	(0.08	)	$	(0.09	)	$	(0.09	)
Net asset value, end of period (x)	$	9.25		$	9.53		$	9.69		$	9.73
Total return (%) (r)(s)(x)	(2.02		)	(0.87		)	0.56			1.44		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	1.12			1.15			1.13			1.23		(a)
Expenses after expense reductions (f)	0.85			0.83			0.83			0.89		(a)
Net investment income	0.70			0.48			0.54			0.56		(a)
Portfolio turnover	36			30			28			29
Net assets at end of period (000 omitted)	$	200,558		$	204,347		$	187,921		$	148,892

(a)	Annualized.

(d)	Per share data is based on average shares outstanding.
(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.
(g)	The per share amount varies from the net realized and unrealized gain/loss for the period because of the timing of sales of fund shares and the per share amount of realized and unrealized gains and losses at such time.
(i)	For the period from the class inception, October 1, 2012, through the stated period end.
(n)	Not annualized.
(r)	Certain expenses have been reduced without which performance would have been lower.
(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.
(t)	Total returns do not include any applicable sales charges.
(w)	Per share amount was less than $0.01.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

MFS Absolute Return Fund

MFS Absolute Return Fund

Shareholder Communications with the Board of Trustees. Shareholders may mail written communications to the Board of Trustees to the attention of the Board of Trustees, [fund name], Massachusetts Financial Services Company, 111 Huntington Avenue, Boston, MA 02199, Attention: Frank Tarantino, Independent Senior Officer of the Fund. Shareholder communications must (i) be in writing and be signed by the shareholder, (ii) identify the MFS fund to which they relate, and (iii) identify the class and number of shares held by the shareholder.

If you want more information about MFS Absolute Return Fund, the following documents are available free upon request:

Annual/Semiannual Reports. These reports contain information about the fund’s actual investments. Annual reports discuss the effect of recent market conditions and investment strategies on the fund’s performance during its last fiscal year.

Statement of Additional Information (SAI). The SAI, dated September 28, 2016, as may be amended or supplemented from time to time, provides more detailed information about the fund and is incorporated into this prospectus by reference.

You can get free copies of the annual/semiannual reports, the SAI and other information about the fund, including current net asset values per share, and make inquiries about the fund, by contacting:

Internet: mfs.com

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

Telephone: 1-800-225-2606

Information about the fund (including its prospectus, SAI and shareholder reports) can be reviewed and copied at the:

U.S. Securities and Exchange Commission

Public Reference Room

Washington, DC 20549-1502

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 on the EDGAR Database on the Commission’s Internet Web site at http://www.sec.gov , and copies of this information may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Room at the above address.

The fund’s Investment Company Act file number is 811-4492.

HOW TO CONTACT US

Web site	Account service and literature	Mailing address
mfs.com	Shareholders	MFS Service Center, Inc.
	1-800-225-2606	P.O. Box 55824
MFS TALK	Investment professionals	Boston, MA 02205-5824
1-800-637-8255	1-800-343-2829
24 hours a day	Retirement plan services	Overnight mail
	1-800-637-1255	MFS Service Center, Inc.
		c/o Boston Financial Data Services
		30 Dan Road
		Canton, MA 02021-2809

September 28, 2016

PROSPECTUS

MFS ® Aggressive Growth Allocation Fund

The investment objective of the fund is to seek a high level of total return consistent with an aggressive level of risk relative to the other MFS Asset Allocation Funds. (The MFS Asset Allocation Funds currently are MFS Conservative Allocation Fund, MFS Moderate Allocation Fund, MFS Growth Allocation Fund, and MFS Aggressive Growth Allocation Fund.)

CLASS		TICKER SYMBOL
Class A		MAAGX
Class B		MBAGX
Class C		MCAGX
Class I		MIAGX
Class 529A		EAGTX
Class 529B		EBAAX
Class 529C		ECAAX
Class R1		MAAFX
Class R2		MAWAX
Class R3		MAAHX
Class R4		MAALX

Table of contents

SUMMARY OF KEY INFORMATION	2
INVESTMENT OBJECTIVE, STRATEGIES, AND RISKS	5
MANAGEMENT OF THE FUND	8
DESCRIPTION OF SHARE CLASSES	9
HOW TO PURCHASE, REDEEM, AND EXCHANGE SHARES	13
OTHER INFORMATION	17
FINANCIAL HIGHLIGHTS	20
APPENDIX A - DESCRIPTION OF UNDERLYING FUNDS	26

The U.S. Securities and Exchange Commission has not approved or disapproved the fund’s shares or determined whether this prospectus is accurate or complete. Anyone who tells you otherwise is committing a crime.

AGG-PRO-092816

MFS Aggressive Growth Allocation Fund

Summary of Key Information

Investment Objective

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 10 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Share Class

529A

B AND
529B

C AND
529C

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

5.75

None

Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)

1.00

% #

None

4.00

1.00

None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Share Class	A		B		C		I		529A		529B		529C		R1		R2		R3		R4
Management Fee	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%	0.00	%
Distribution and/or Service (12b-1) Fees	0.25	%	1.00	%	1.00	%	None		0.25	%	1.00	%	1.00	%	1.00	%	0.50	%	0.25	%	None
Other Expenses	0.15	%	0.15	%	0.15	%	0.15	%	0.25	%	0.25	%	0.25	%	0.15	%	0.15	%	0.15	%	0.15	%
Acquired (Underlying) Fund Fees and Expenses	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%	0.74	%
Total Annual Fund Operating Expenses	1.14	%	1.89	%	1.89	%	0.89	%	1.24	%	1.99	%	1.99	%	1.89	%	1.39	%	1.14	%	0.89	%
Fee Reductions and/or Expense Reimbursements 1	(0.02	)%	(0.02	)%	(0.02	)%	(0.02	)%	(0.07	)%	(0.07	)%	(0.07	)%	(0.02	)%	(0.02	)%	(0.02	)%	(0.02	)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	1.12	%	1.87	%	1.87	%	0.87	%	1.17	%	1.92	%	1.92	%	1.87	%	1.37	%	1.12	%	0.87	%

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

MFS Aggressive Growth Allocation Fund

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.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR		3 YEARS		5 YEARS		10 YEARS
Class A Shares	$	683	$	915	$	1,165	$	1,880
Class B Shares assuming
redemption at end of period	$	590	$	892	$	1,219	$	2,014
no redemption at end of period	$	190	$	592	$	1,019	$	2,014
Class C Shares assuming
redemption at end of period	$	290	$	592	$	1,019	$	2,210
no redemption at end of period	$	190	$	592	$	1,019	$	2,210
Class I Shares	$	89	$	282	$	491	$	1,094
Class 529A Shares	$	687	$	939	$	1,210	$	1,983
Class 529B Shares assuming
redemption at end of period	$	595	$	918	$	1,266	$	2,117
no redemption at end of period	$	195	$	618	$	1,066	$	2,117
Class 529C Shares assuming
redemption at end of period	$	295	$	618	$	1,066	$	2,311
no redemption at end of period	$	195	$	618	$	1,066	$	2,311
Class R1 Shares	$	190	$	592	$	1,019	$	2,210
Class R2 Shares	$	139	$	438	$	759	$	1,667
Class R3 Shares	$	114	$	360	$	626	$	1,384
Class R4 Shares	$	89	$	282	$	491	$	1,094

Portfolio Turnover

Principal Investment Strategies

The fund is designed to provide diversification among different asset classes by investing its assets in other mutual funds advised by MFS (Massachusetts Financial Services Company, the fund’s investment adviser), referred to as underlying funds. The underlying funds are selected following a two stage asset allocation process. The first stage is a strategic asset allocation to determine the percentage of the fund’s assets to be invested in the general asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an allocation to underlying funds that have less traditional investment strategies that MFS believes provide diversification benefits when added to a portfolio consisting of stock and bond funds (referred to as Specialty Funds) based on the risk/return potential of the different asset classes and the risk profile of the fund. The second stage involves the actual selection of underlying funds to represent the asset classes based on underlying fund classifications, historical risk, performance, and other factors. Within the stock fund allocations, MFS seeks to diversify globally (by including domestic and international underlying funds), in terms of market capitalization (by including large, mid, and small capitalization underlying funds), and by style (by including both growth and value underlying funds).

As of September 1, 2016, the fund’s approximate target allocation among asset classes and the underlying funds was:

Bond Funds:	0.0	%
International Stock Funds:	30.0	%
MFS Emerging Markets Equity Fund	2.0	%
MFS International Growth Fund	8.0	%
MFS International New Discovery Fund	4.0	%
MFS International Value Fund	8.0	%
MFS Research International Fund	8.0	%
U.S. Stock Funds:	60.0	%
MFS Growth Fund	13.0	%
MFS Mid Cap Growth Fund	10.0	%
MFS Mid Cap Value Fund	10.0	%
MFS New Discovery Fund	2.5	%
MFS New Discovery Value Fund	2.5	%
MFS Research Fund	9.0	%
MFS Value Fund	13.0	%
Specialty Funds:	10.0	%
MFS Commodity Strategy Fund	5.0	%
MFS Global Real Estate Fund	5.0	%

All percentages are rounded to the nearest tenth of a percent.

Principal Risks

The principal risks of investing in the fund are:

Allocation Risk: MFS’ assessment of the risk/return potential of asset classes and underlying funds, and the resulting allocation among asset classes and underlying funds, may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Underlying Funds Risk: MFS’ strategy of investing in underlying funds exposes the fund to the risks of the underlying funds. Each underlying fund pursues its own investment objective and strategies and may not achieve its objective. In addition, shareholders of the fund will indirectly bear the fees and expenses of the underlying funds.

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

MFS Aggressive Growth Allocation Fund

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Real Estate-Related Investment Risk: The risks of investing in real estate-related securities include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the real estate investment trust (REIT) manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

Industry and Sector Focus Risk: Issuers in an industry or sector can react similarly to market, economic, political, regulatory, geopolitical, and other conditions. If MFS invests a significant percentage of the fund’s assets in issuers within an industry or sector, the fund’s performance will be affected by conditions in that industry or sector.

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at a price or time that is not advantageous in order to meet redemptions or other cash needs.

Investment Selection Risk: MFS’ investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Performance Information

The total return for the six-month period ended June 30, 2016, was 3.78%. During the period(s) shown in the bar chart, the highest quarterly return was 19.81% (for the calendar quarter ended June 30, 2009) and the lowest quarterly return was (24.63)% (for the calendar quarter ended December 31, 2008).

MFS Aggressive Growth Allocation Fund

Performance Table.

Average Annual Total Returns

(For the Periods Ended December 31, 2015)

Share Class	1 YEAR		5 YEARS		10 YEARS
Returns Before Taxes
B Shares	(4.66	)%	6.66	%	4.97	%
C Shares	(1.79	)%	6.97	%	4.82	%
I Shares	0.11	%	8.03	%	5.88	%
529A Shares	(5.91	)%	6.45	%	4.84	%
529B Shares	(4.72	)%	6.59	%	4.87	%
529C Shares	(1.85	)%	6.93	%	4.71	%
R1 Shares	(0.89	)%	6.97	%	4.80	%
R2 Shares	(0.35	)%	7.51	%	5.32	%
R3 Shares	(0.09	)%	7.78	%	5.58	%
R4 Shares	0.16	%	8.07	%	5.86	%
A Shares	(5.88	)%	6.50	%	4.95	%
Returns After Taxes on Distributions
A Shares	(6.98	)%	6.03	%	4.45	%
Returns After Taxes on Distributions and Sale of Fund Shares
A Shares	(2.39	)%	5.09	%	3.94	%
Index Comparisons (Reflects no deduction for fees, expenses, or taxes)
Standard & Poor’s 500 Stock Index	1.38	%	12.57	%	7.31	%
MFS Aggressive Growth Allocation Fund Blended Index	(0.54	)%	8.43	%	5.56	%

As of December 31, 2015, the MFS Aggressive Growth Allocation Fund Blended Index (the “Blended Index”) consisted of the following indices and weightings: 60% Standard & Poor’s 500 Stock Index; 30% MSCI EAFE (Europe, Australasia, Far East) Index; 5% Bloomberg Commodity Index; and 5% FTSE EPRA/NAREIT Developed Real Estate Index. The components and weightings of the Blended Index may have differed during the period, and may differ in the future.

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager		Since		Title
Joseph C. Flaherty, Jr.		2002		Investment Officer of MFS

Purchase and Sale of Fund Shares

The fund’s initial and subsequent investment minimums generally are as follows:

Class	Initial Minimum	Subsequent Minimum
Class A, Class B, Class C	None – automatic investment plans and certain asset-based fee programs $25 – employer-sponsored retirement plans $250 – Traditional and Roth IRAs $1,000 – other accounts	$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives None – other purchases
Class I, Class R1, Class R2, Class R3, Class R4	None	None
Class 529A, Class 529B, Class 529C	None – automatic investment plans $250 – other accounts	None

Taxes

Payments to Broker/Dealers and Other Financial Intermediaries

Investment Objective, Strategies, and Risks

Investment Objective

The fund’s investment objective is to seek a high level of total return consistent with an aggressive level of risk relative to the other MFS Asset Allocation Funds. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

MFS Aggressive Growth Allocation Fund

Massachusetts Financial Services Company (referred to as MFS or the Adviser), following a two stage asset allocation process. The first stage is a strategic asset allocation to determine the percentage of the fund’s assets to be invested in the general asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an allocation to underlying funds that have less traditional investment strategies that MFS believes provide diversification benefits when added to a portfolio consisting of stock and bond funds (referred to as Specialty Funds) based on the risk/return potential of the different asset classes and the risk profile of the fund. The asset class allocations provide an initial layer of diversification for the fund.

As of September 1, 2016, the fund’s approximate target allocation among asset classes was:

Bond Funds:	0	%
International Stock Funds:	30	%
U.S. Stock Funds:	60	%
Specialty Funds:	10	%

All percentages are rounded to the nearest tenth of a percent.

The second stage involves the actual selection of underlying funds to represent the asset classes based on underlying fund classifications, historical risk, performance, and other factors. This selection process provides a second layer of diversification within both stock and bond fund allocations. Within the stock fund allocations, MFS seeks to diversify globally (by including domestic and international underlying funds), in terms of market capitalization (by including large, mid, and small capitalization underlying funds), and by style (by including both growth and value underlying funds).

As of September 1, 2016, the fund’s approximate target allocation among underlying funds was:

Bond Funds:	0.0	%
International Stock Funds:	30.0	%
MFS Emerging Markets Equity Fund	2.0	%
MFS International Growth Fund	8.0	%
MFS International New Discovery Fund	4.0	%
MFS International Value Fund	8.0	%
MFS Research International Fund	8.0	%
U.S. Stock Funds:	60.0	%
MFS Growth Fund	13.0	%
MFS Mid Cap Growth Fund	10.0	%
MFS Mid Cap Value Fund	10.0	%
MFS New Discovery Fund	2.5	%
MFS New Discovery Value Fund	2.5	%
MFS Research Fund	9.0	%
MFS Value Fund	13.0	%
Specialty Funds:	10.0	%
MFS Commodity Strategy Fund	5.0	%
MFS Global Real Estate Fund	5.0	%

All percentages are rounded to the nearest tenth of a percent.

Although the underlying funds are categorized generally as Bond Funds, Stock Funds (International or U.S.), or Specialty Funds, many of the underlying funds can invest in a mix of securities (e.g., a U.S. Stock Fund can invest in international stocks, or a Specialty Fund can invest in stocks and/or bonds).

The asset class allocations and the underlying funds and their target weightings are not designed to take advantage of short-term market opportunities and have been selected for investment over longer time periods. The asset class allocations and the underlying funds and their target weightings may be changed without shareholder approval or notice. The actual weightings can deviate due to market movements and cash flows. MFS systematically rebalances the fund’s investments in the underlying funds.

A description of the underlying funds is set forth in Appendix A of this prospectus.

Principal Investment Types of the Underlying Funds

The principal investment types in which the underlying funds may invest are:

Equity Securities: Equity securities represent an ownership interest, or the right to acquire an ownership interest, in a company or other issuer. Different types of equity securities provide different voting and dividend rights and priorities in the event of bankruptcy of the issuer. Equity securities include common stocks, preferred stocks, securities convertible into stocks, equity interests in REITs, and depositary receipts for such securities.

Real Estate-Related Investments: Real estate-related investments include REITs, issuers similar to REITs formed under the laws of non-U.S. countries, and other U.S. and foreign issuers that earn at least 50% of their gross revenues or net profits from real estate activities or from products or services related to the real estate sector. Real estate activities include owning, developing, managing, or acting as a broker for real estate. Examples of real estate products or services include building supplies and mortgage servicing. REITs are pooled investment vehicles that invest primarily in income-producing real estate or real estate-related loans or interests. Equity REITs invest most of their assets directly in U.S. or foreign real property, receive most of their income from rents and may also realize gains by selling appreciated property. Mortgage REITs invest most of their assets in real estate mortgages and receive most of their income from interest payments. Hybrid REITs combine the characteristics of both equity REITs and mortgage REITs.

Commodity-Linked Derivatives: Commodity-linked derivatives are derivatives whose value is based on the value of a commodity, a commodity futures or option contract, a commodity index, or some other indicator that reflects the value of a particular commodity or commodity market or the difference between one or more commodities or commodity markets (“commodity indicator”). Commodity-linked derivatives include notes, futures, options, and swaps.

Principal Risks

The share price of the fund will change daily based on the performance of the underlying funds. Underlying fund performance will change daily based on changes in market, economic, industry, political, regulatory, geopolitical, and other conditions. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

MFS Aggressive Growth Allocation Fund

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Commodity-Related Investments Risk: The value of commodity-related investments may be more volatile than the value of equity securities or debt instruments and may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The price of a commodity-related investment may be affected by demand/supply imbalances in the market for the commodity. These imbalances may be significant

MFS Aggressive Growth Allocation Fund

due to the length of time required to alter the supply of some commodities in response to changes in demand.

Other Investment Strategies and Risks

Management of the Fund

Investment Adviser

The fund pays no management fee to MFS; however the underlying funds pay management fees to MFS which are reflected under “Summary of Key Information-Fees and Expenses” above.

MFS has agreed in writing to bear the fund’s expenses, excluding program management fees, management fees, distribution and service fees, interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses, including fees and expenses associated with investments in investment companies and other similar investment vehicles, such that “Other Expenses” do not exceed 0.13% of the class’ average daily net assets annually for each class of shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

A discussion regarding the basis for the Board of Trustees’ approval of the Investment Advisory Agreement is available in the fund’s semiannual report for the six-month period that ended November 30, 2015.

Disclosure of Portfolio Holdings . The fund has established a policy with respect to the disclosure of fund portfolio holdings. A description of this policy is provided in the SAI.

Information		Approximate Date of Posting To Web Site
Fund’s top 10 holdings as of each month’s end		14 days after month end
Fund’s full holdings as of each month’s end		24 days after month end

Top 10 holdings are aggregated disclosed holdings of the underlying MFS funds.

Note that the fund or MFS may suspend the posting of this information or modify the elements of this Web posting policy without notice to shareholders. Once posted, the above information

MFS Aggressive Growth Allocation Fund

will generally remain available on the Web site until at least the date on which the fund files a Form N-CSR or Form N-Q for the period that includes the date as of which the Web site information is current.

Portfolio Manager(s)

Portfolio Manager		Primary Role		Five Year History
Joseph C. Flaherty, Jr.		Portfolio Manager, General Oversight of a Team of Investment Professionals		Employed in the investment area of MFS since 1993.

Administrator

Distributor

MFS Fund Distributors, Inc. (“MFD”), a wholly owned subsidiary of MFS, is the distributor of shares of the fund.

Shareholder Servicing Agent

Special Servicing Agreement

Under a Special Servicing Agreement among MFS, certain underlying funds, and the fund, certain underlying funds pay to MFSC a portion of the transfer-agent-related expenses of the fund, including sub-accounting fees payable to financial intermediaries, to the extent that such payments are less than the amount of the benefits realized or expected to be realized by the underlying fund from the investment in the underlying fund by the fund.

Program Manager(s)

MFD serves as program manager for a qualified tuition program under Section 529 of the Internal Revenue Code of 1986, as amended, through which 529 share classes of the fund are included as investment options to program participants. MFD provides, either directly or through third parties, recordkeeping, tax reporting, and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements under a Master 529 Administrative Services Agreement. The fund’s 529 share classes may also be offered through qualified tuition programs for which MFD does not serve as program manager.

Under the Master 529 Administrative Services Agreement, the fund pays MFD an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD pays all or a portion of this fee to third parties. MFD has agreed in writing to waive the program management fee for each of the fund’s Class 529A, Class 529B, and Class 529C shares to 0.05% of the class’ average daily net assets attributable to each share class annually. This written agreement will expire on September 30, 2017, unless MFD elects to extend the waiver.

Qualified tuition program accounts for which MFD serves as program manager may be subject to a $25 annual account maintenance fee. Please consult the program description for your particular qualified tuition program for a discussion of account fees as well as the fees paid to and services received from the program manager.

Description of Share Classes

The fund offers Class A, Class B, Class C, Class I, Class 529A, Class 529B, Class 529C, Class R1, Class R2, Class R3, and Class R4 shares through this prospectus. All classes of the fund have the same investment objective and investments, but each class has its own sales charge and expense structure. Your financial intermediary may also charge you additional fees, commissions, or other charges. You should consult with your financial intermediary to help you determine which class is most appropriate for you.

Class I shares generally are available only to the following eligible investors:

· certain retirement plans established for the benefit of employees and former employees of MFS or its affiliates;

· defined benefit retirement plans, endowments or foundations;

· bank trust departments or law firms acting as trustee or manager for trust accounts;

· investors who purchase shares through asset-based fee programs available through financial intermediaries;

In addition, MFD may accept, in its sole discretion, investments in Class I shares from purchasers not listed above.

Class 529A, Class 529B and Class 529C shares generally are available only to qualified tuition programs established in accordance with Section 529 of the Internal Revenue Code of 1986, as amended (tuition programs).

MFS Aggressive Growth Allocation Fund

available to retail non-retirement accounts, traditional and Roth IRAs, Coverdell Educational Savings Accounts, SEPs, SAR-SEPs, SIMPLE IRAs, salary reduction only 403(b) plans, and 529 tuition plans.

Shareholders may be able to convert between Class A shares and Class I shares of the fund if they satisfy eligibility requirements for the other class, if any.

Class C shareholders may be able to convert their Class C shares not subject to a CDSC to Class I shares of the fund if they satisfy eligibility requirements.

Sales Charges and Waivers or Reductions

You may be subject to an initial sales charge when you purchase Class A or Class 529A shares, or a CDSC when you redeem Class A, Class B, Class C, Class 529B or Class 529C shares. These sales charges are paid to MFD.

In the circumstances described below, you may qualify for a sales charge waiver or reduction for purchases or redemptions of Class A, Class B, Class C, Class 529A, Class 529B, and Class 529C shares. In addition, other sales charge waivers or reductions apply to certain transactions by retirement plans, Section 529 tuition programs, and certain other groups (e.g., affiliated persons of MFS) and with respect to certain types of investment programs (e.g., asset-based fee programs available through certain financial intermediaries). Details regarding the types of investment programs and categories of investors eligible for these waivers or reductions are provided in the SAI, which is available to you free of charge and on the fund’s Web site at mfs.com . Some of these programs and waivers or reductions are not available to you if your shares are held through certain types of accounts, such as retirement accounts and 529 plans, or certain accounts that you have with your financial intermediary. Waivers or reductions may be eliminated, modified, and added at any time without providing advance notice to shareholders.

Class A and Class 529A Shares. You may purchase Class A and Class 529A shares at the offering price (which includes the applicable initial sales charge).

The amount of the initial sales charge you pay when you buy Class A or Class 529A shares differs depending upon the amount you invest, as follows:

	INITIAL SALES CHARGE AS PERCENTAGE OF:
Amount of Purchase	GROSS PURCHASE AMOUNT (OFFERING PRICE*)		NET AMOUNT INVESTED
Less than $50,000	5.75	%	6.10	%
$50,000 but less than $100,000	4.75	%	4.99	%
$100,000 but less than $250,000	3.75	%	3.90	%
$250,000 but less than $500,000	2.75	%	2.83	%
$500,000 but less than $1,000,000	2.00	%	2.04	%
$1,000,000 or more	None		None

You may purchase Class A and Class 529A shares without an initial sales charge when you invest $1 million or more in Class A and Class 529A shares. However, for Class A shares purchased without an initial sales charge, for purchasers other than Employer Retirement Plans, a CDSC of 1% will generally be deducted from your redemption proceeds if you redeem within 18 months of purchase.

Class B and Class 529B Shares. You may purchase Class B and Class 529B shares at net asset value without an initial sales charge, but if you redeem your shares within the first six years after purchase, you may be subject to a CDSC (declining from 4% during the first year to 0% after six years).

The CDSC is imposed according to the following schedule:

Year of redemption after purchase		1st		2nd		3rd		4th		5th		6th		7th
Contingent deferred sales charge		4	%	4	%	3	%	3	%	2	%	1	%	0	%

If you hold Class B or Class 529B shares for approximately eight years, they will convert to Class A or Class 529A shares of the fund, respectively. All Class B or Class 529B shares you acquire through the reinvestment of dividends and distributions will be held in a separate sub-account. Each time any Class B or Class 529B shares in your account convert to Class A or Class 529A shares, a proportionate number of the Class B or Class 529B shares in the sub-account will also convert to Class A or Class 529A shares, respectively.

Class C and Class 529C Shares. You may purchase Class C or Class 529C shares at net asset value without an initial sales charge. However, a CDSC of 1% will generally be deducted from your redemption proceeds if you redeem within 12 months of your purchase.

Class I Shares. Eligible investors may purchase Class I shares at net asset value without an initial sales charge or a CDSC upon redemption.

Class R1, Class R2, Class R3, and Class R4 Shares. Employer Retirement Plans may purchase Class R1, Class R2, Class R3, and Class R4 shares at net asset value without an initial sales charge or a CDSC upon redemption.

MFS Aggressive Growth Allocation Fund

	INVESTMENTS ELIGIBLE FOR:
Program	WAIVED INITIAL SALES CHARGE	REDUCED INITIAL SALES CHARGE	WAIVED CDSC
Letter of Intent		X
Right of Accumulation		X
Automatic Exchange Plan	X*
Exchange Privilege	X*
Systematic Withdrawal Plan			X**
Distribution Reinvestment	X
Distribution Investment Program	X
Reinstatement Privilege	X
Other Sales Charge Waivers	X		X

* Investments under the Automatic Exchange Plan or certain other exchanges may be subject to a sales charge in certain cases.

** Limited for Class A, Class B, Class C, Class 529B, and Class 529C shares.

· Letter Of Intent (LOI). You may pay a reduced or no initial sales charge on purchases of Class A or Class 529A shares if you intend to invest a specific dollar amount, based on the gross amount of your investment (including the amount of any sales charge paid), including investments through any linked accounts in any class of any MFS fund within a 13-month period (36 months for a $1 million commitment). Distributions reinvested in additional shares of the fund or distributions from other MFS funds automatically invested in shares of the fund will not apply toward the satisfaction of the LOI.

· Right Of Accumulation (ROA). Under the ROA, you may pay a reduced or no initial sales charge on purchases of Class A or Class 529A shares by aggregating the total dollar amount of your investment with your existing investments or any linked accounts invested in MFS funds, based on the current maximum public offering price of the funds. For example, you will pay a sales charge on your current purchase at the rate applicable to the total value of all eligible accounts based on the sales charge schedule above.

· Linking Accounts For LOI and ROA. For purposes of obtaining reduced sales charges under the LOI and ROA, you may combine the value of your accounts with those of your spouse (or legal equivalent under applicable state law) and your children under the age of 21.

Eligible accounts that you may link under an LOI and ROA are:

· Individual accounts;

· Joint accounts;

· Trust accounts of which you, your spouse (or legal equivalent under applicable state law), or child under the age of 21 is the grantor;

· MFS 529 College Savings Plan accounts;

· Certain single-participant retirement plan accounts;

· Certain Individual Retirement Accounts;

· Uniform Gifts/Transfers to Minor Acts accounts; and

· Accounts held in the name of your financial intermediary on your behalf.

MFS Aggressive Growth Allocation Fund

· Automatic Exchange Plan (not available for Class R1, Class R2, Class R3, and Class R4 shares). If you have a balance of at least $2,000 in your account in the fund, you may participate in the automatic exchange plan, a dollar-cost averaging program. This plan permits you to make automatic periodic exchanges from your account in the fund for shares of the same class of other MFS funds. Exchanges will generally be made at net asset value without any sales charges. Shares otherwise subject to a CDSC will not be charged a CDSC in an exchange. Shares will retain the CDSC schedule in effect based upon a pro rata share of the CDSC from the exchanged fund and the original purchase date of the shares subject to the CDSC.

· Systematic Withdrawal Plan. If you have a balance of at least $5,000 in your account in the fund, you may elect to receive (or designate someone else to receive) regular periodic payments (of at least $50 if by check) through an automatic redemption of Class A, Class B, Class C, Class I, Class 529A, Class 529B, or Class 529C shares. For Class A, Class B, Class C, Class 529B, or Class 529C shares, you may incur a CDSC when Class A, Class B, Class C, Class 529B, or Class 529C shares are redeemed under the plan (or plans if more than one plan is established) if greater than 10% of the value of your account is withdrawn under the plan(s) in any one year (determined at the time of your first withdrawal under the plan(s), or January 4, 2016, with respect to Class A shares, January 3, 2007, with respect to Class B or Class 529B shares, or January 2, 2008, with respect to Class C or Class 529C shares, whichever is later). The applicable CDSC will be prorated across all of your payments taken in the one year period.

· Distribution Reinvestment. You may automatically reinvest dividend and capital gain distributions in the same fund without paying an initial sales charge.

Any CDSC paid upon the redemption of Class B shares will not be credited to your account.

Calculation Of CDSC. As discussed above, certain investments in Class A, Class B, Class C, Class 529B, and Class 529C shares are subject to a CDSC. For purposes of calculating the CDSC, purchases made on any day during a calendar month will age one month at the close of business on the last day of that month, and at the close of business on the last day of each subsequent month. The CDSC is based on the original purchase cost or the current market value of the shares being sold, whichever is less. For purposes of determining the CDSC, if you sell only some of your shares, shares not subject to a CDSC are sold first, followed by shares held the longest.

Shares acquired through reinvestment of distributions are not subject to a CDSC.

Distribution and Service Fees

The fund has adopted a plan in accordance with Rule 12b-1 under the Investment Company Act of 1940, as amended (the “Distribution Plan”). Under the Distribution Plan, the fund pays distribution and/or service fees to MFD to support the sale and distribution of Class A, Class B, Class C, Class 529A, Class 529B, Class 529C, Class R1, Class R2, and Class R3 shares, and/or shareholder servicing and account maintenance activities. These distribution and/or service fees equal on an annual basis up to the following maximum percentages of average daily net assets of the class:

CLASS	MAXIMUM DISTRIBUTION FEE		MAXIMUM SERVICE FEE		MAXIMUM TOTAL DISTRIBUTION AND SERVICE FEE
Class A	0.00	%	0.25	%	0.25	%
Class B	0.75	%	0.25	%	1.00	%
Class C	0.75	%	0.25	%	1.00	%
Class 529A	0.00	%	0.25	%	0.25	%
Class 529B	0.75	%	0.25	%	1.00	%
Class 529C	0.75	%	0.25	%	1.00	%
Class R1	0.75	%	0.25	%	1.00	%
Class R2	0.25	%	0.25	%	0.50	%
Class R3	0.00	%	0.25	%	0.25	%

The fund has not adopted a Rule 12b-1 plan with respect to its Class I or Class R4 shares.

Financial Intermediary Compensation

MFS Aggressive Growth Allocation Fund

received and expected to be received by MFD from shareholders and Distribution Plan distribution and service payments received by MFD from the fund, (ii) in the form of 529 administrative services payments and shareholder servicing payments paid by MFD and/or one or more of its affiliates (for purposes of this section only, collectively, “MFD”) based on the receipt of such payments by MFD from the fund, and (iii) in the form of payments paid by MFD from MFD’s own additional resources.

Financial intermediaries may receive up-front commissions of up to the following percentage amounts for sales of the following share classes:

SHARE CLASS	UP FRONT COMMISSION AS A PERCENTAGE OF OFFERING PRICE
Class A or Class 529A	5.75	%
Class B or Class 529B	3.75	%
Class C or Class 529C	1.00	%

How To Purchase, Redeem, and Exchange Shares

How to Purchase Shares

Your shares will be bought at the offering price (the net asset value per share plus any applicable initial sales charge) next calculated after your purchase order is received in proper form. Your financial intermediary is responsible for transmitting your purchase order to the fund in proper form and in a timely manner. MFSC reserves the right to reject any purchase order that is not in proper form. The specific requirements for proper form depend on the type of account and transaction and the method of purchase; contact MFSC if you have questions about your particular circumstances. Certain restrictions apply to the use of a transfer on death registration. You or your financial intermediary should contact MFSC to obtain a Transfer on Death registration form and for information regarding MFSC’s other requirements for transfer on death registrations. If payment for a purchase order is not received by the time required under applicable law, your purchase order may be cancelled and your financial intermediary could be liable for any costs or losses.

Class A, Class B, and Class C Shares. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

MFS Aggressive Growth Allocation Fund

Class I Shares. You can establish an account through your MFD representative, by having your financial intermediary process your purchase, or by contacting MFSC directly.

Class R1, Class R2, Class R3, and Class R4 Shares. You can establish an account through your financial intermediary or by contacting MFSC directly.

529 Share Classes. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

Purchases of Class 529B shares are subject to a total account value limitation at the time of purchase of $99,999, and purchases of Class 529C shares are subject to a total account value limitation at the time of purchase of $999,999. If your existing accounts for all share classes held with the MFS funds have a total value equal to $99,999 for Class 529B share purchases or $999,999 for Class 529C share purchases, you will not be able to purchase Class 529B or Class 529C shares, as applicable. For the purpose of determining your total account value, existing accounts for all share classes held with the MFS funds that are linked under a LOI or ROA will be included.

In addition, the Internal Revenue Code of 1986, as amended and tuition programs impose a maximum total contribution limitation for designated beneficiaries on behalf of whom assets under tuition programs are held, which may result in a limitation on your ability to purchase the fund’s 529 share classes. Please see the program description for details concerning the maximum contribution limitation and its application. An account owner of a newly-established account under a tuition program in which the designated beneficiary is age 12 or older will not be permitted to purchase Class 529B shares, unless the newly established account results from a transfer of registration from another MFS fund account. Please see the program description for details and additional restrictions.

Additional Purchases

You may purchase additional shares through your financial intermediary or MFSC.

· Additional Purchases Directly Through MFSC.

· Mail. You may purchase additional shares by mailing a check with your investment instructions to MFSC.

· Internet. You may purchase additional shares from a pre-designated bank account via the Internet at mfs.com (MFS Access). You must elect this privilege on your account application or service application and establish a password on MFS Access to use this service. Purchases via the Internet are not available for Class R1, Class R2, Class R3, and Class R4 shares, and certain types of accounts.

· Wire. To purchase additional shares by wire, call MFSC for instructions.

· Additional Purchases Through Your Financial Intermediary. You can have your financial intermediary purchase shares on your behalf. Your financial intermediary will be responsible for furnishing all necessary documents to MFSC and may charge you for this service.

How to Redeem Shares

Your shares will be sold at the net asset value per share next calculated after your redemption order is received in proper form, minus any applicable CDSC and/or other fees. Your financial intermediary is responsible for transmitting your redemption order to the fund in proper form and in a timely manner. MFSC reserves the right to reject any redemption request that is not in proper form. The specific requirements for proper form depend on the type of account and transaction and the method of redemption; contact MFSC if you have questions about your particular circumstances. A redemption order in an amount less than or equal to the value of your account (other than an exchange) is considered to be in proper form only with respect to shares in your account for which payment has been received and collected. A new redemption order must be submitted if you wish to redeem your shares for which payment had not been received and collected at the time the prior redemption order was received by the fund. Receiving and collecting payment can take up to seven business days after a purchase. In certain circumstances, you will need to have your signature guaranteed and/or submit additional documentation to redeem your shares. In general, no signature guarantee is required for a redemption order for up to $100,000 that is signed by all owners or fiduciaries identified in the account registration, paid as registered, and mailed to the address of record. However, if you have changed your address of record within 30 days of your redemption order, a signature guarantee may be required.

You may redeem your shares either by having your financial intermediary process your redemption or by contacting MFSC directly.

Redeeming Directly Through MFSC.

MFS Aggressive Growth Allocation Fund

redemptions are not available for certain types of accounts.

· Internet. If a signature guarantee is not required, you can have shares redeemed from your account via the Internet at mfs.com (MFS Access) and the proceeds mailed to the address of record on the account. You can also have shares redeemed from your account via MFS Access and the proceeds sent directly to a pre-designated bank account. You must elect this privilege on your account application or service application and establish a password on MFS Access to use this service. Redemptions via the Internet are not available for Class R1, Class R2, Class R3, and Class R4 shares, and certain types of accounts.

· Systematic Withdrawal Plan. For Class A, Class B, Class C, Class I, Class 529A, Class 529B, or Class 529C shares, you may elect to automatically receive (or designate someone else to receive) regular periodic payments through an automatic redemption of such classes. Please contact MFSC for details.

How to Exchange Shares

An exchange involves the redemption of shares of one fund and the purchase of shares of another fund.

Exchange Privilege. You can exchange your shares for shares of the same class of most other MFS funds by having your financial intermediary process your exchange request or by contacting MFSC directly.

You can exchange your Class A shares and your Class I shares for shares of the MFS U.S. Government Money Market Fund, if available, according to the terms of such fund’s prospectus.

Your ability to exchange your Class 529A, Class 529B, or Class 529C shares of the fund for corresponding Class 529A, Class 529B, and Class 529C shares of other MFS funds may be limited under Section 529 of the Internal Revenue Code of 1986, as amended and the tuition program through which your investment in the MFS funds is made. Please see the tuition program description for details.

Other Considerations

Disruptive Trading

MFS Aggressive Growth Allocation Fund

MFSC will generally restrict, reject or cancel purchase and exchange orders into the fund if MFSC determines that an accountholder has made two exchanges, each in an amount of $15,000 or more, out of an account in the fund during a calendar quarter (“two exchange limit”). This policy does not apply to MFS money market funds or to exchanges initiated by a retirement plan trustee or sponsor rather than by a plan participant, and other similar non-discretionary exchanges (e.g., in connection with fund mergers/acquisitions/liquidations). MFSC may make exceptions to this policy if, in its judgment, the transaction does not represent frequent trading activity, such as purchases made through systematic purchase plans (but not systematic exchange plans), payroll contributions, or distribution investment programs. In applying this policy, MFSC considers the information available to it at the time and reserves the right to consider trading effected through multiple accounts that are under common ownership, control, or influence to be trading out of a single account.

With respect to omnibus accounts that provide MFSC with underlying shareholder data daily, MFSC will apply the two exchange limit directly to underlying shareholders. For all other accounts which MFSC determines are omnibus accounts, MFSC will apply the two exchange limit to the omnibus account itself. Applying the two exchange limit to the omnibus account itself will not necessarily detect violations of the two exchange limit by underlying shareholders. If the financial intermediary associated with an omnibus account that has triggered the two exchange limit demonstrates to MFSC, as determined in MFSC’s sole discretion, that no single underlying shareholder triggered the two exchange limit, then MFSC will remove any restrictions, rejections or cancellations imposed on the account. If the financial intermediary demonstrates to MFSC that a single underlying shareholder triggered the two exchange limit and that the financial intermediary itself will apply applicable restrictions, rejections or cancellations to that underlying shareholder, MFSC will likewise remove any restrictions, rejections or cancellations imposed on the omnibus account. Otherwise, MFSC will continue to apply the two exchange limit to the omnibus account.

MFSC reviews trading activity to detect trading activity that may be indicative of frequent trading based on its internal parameters for detecting frequent trading, including reviewing transactions (including exchanges) that exceed a certain dollar amount, transactions involving similar dollar amounts, or transactions that occur close in time to other transactions in the same account or in multiple accounts that are under common ownership or influence. Any or all of these parameters (including those not listed) may change at any time. If MFSC detects suspicious trading activity at the omnibus account level, it will contact the financial intermediary to request underlying shareholder level activity to determine whether there is underlying shareholder level frequent trading. However, the underlying shareholder data received may not reflect information about the ultimate underlying shareholders because there may be multiple layers of omnibus accounts. If frequent trading is identified, MFSC will take appropriate action, such as requesting the financial intermediary to prohibit purchases into the account by the underlying shareholder, requiring purchases by the underlying shareholder to be submitted only by mail, or prohibiting purchases from the financial intermediary.

Ability to Contact MFSC. Certain methods of contacting MFSC, such as by mail, telephone, or electronically, may be unavailable or delayed (for example, after natural disasters, during periods of

MFS Aggressive Growth Allocation Fund

significant/major political, social, or economic instability, or in the event of a cybersecurity incident).

Other Information

Valuation

To determine net asset value, the fund’s investments for which reliable market quotations are readily available are valued at market value, and funds in which the fund invests are generally valued at their net asset value per share. Certain short term debt instruments may be valued at amortized cost.

Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. These valuations can be based on both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data.

In addition, investments may be valued at fair value if MFS determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as a foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, foreign equity securities may often be valued at fair value. MFS generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Distributions

The fund intends to declare and pay any dividends to shareholders at least annually.

Any capital gains are distributed at least annually.

Distribution Options

The following distribution options are generally available:

· Dividend and capital gain distributions automatically reinvested in additional shares (this option will be assigned if no other option is specified) ;

· Dividend distributions in cash; capital gain distributions automatically reinvested in additional shares;

· Dividend and capital gain distributions in cash; or

· Dividend and capital gain distributions automatically reinvested into the same class of shares of another MFS Fund.

Not all options are available for every class or every account.

Dividends and capital gain distributions for Class 529A, Class 529B, Class 529C, Class R1, Class R2, Class R3, and Class R4 shares automatically will be reinvested in additional shares of the fund.

MFS Aggressive Growth Allocation Fund

to be effective for that distribution. No interest will accrue on amounts represented by uncashed distribution checks.

Tax Considerations

Any gain resulting from the redemption, sale, or exchange of your shares will generally also be subject to tax.

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 or is deemed to have owned the investments that generated them, rather than how long you have owned your shares. Distributions of gains from the sale of investments that the fund owned for more than one year and that are properly reported by the fund as capital gain dividends will be treated as long-term capital gains includible in net capital gain and taxed to individuals at reduced rates. Distributions of gains from the sale of investments that the fund owned for one year or less will be taxable as ordinary income. If some or all of the fund’s income derives from “qualified dividend income” and if you are an individual who meets holding period and other requirements with respect to the fund’s shares, those distributions that are properly reported by the fund as derived from qualified dividend income are taxed to you at the reduced rates applicable to net capital gains. The portion of the fund’s distributions that will be derived from qualified dividend income will increase with increased allocations to stock fund classes.

Investing in underlying funds could affect the amount, timing, and character of distributions from the fund, and, therefore, may increase the amount of taxes payable by shareholders.

Investments by the underlying funds in foreign securities may be subject to foreign withholding or other taxes, which will decrease the fund’s return on those securities.

If at the close of each quarter of the fund’s taxable year, at least 50% of its total assets consists of interests in other regulated investment companies, the fund will be permitted to elect to pass through to its shareholders foreign income and other similar taxes paid by the fund in respect of foreign securities it holds directly or by an underlying fund that itself was eligible to elect and so elected to pass such taxes through to shareholders. If the fund makes such election, you must include your share of those taxes in gross income as a distribution from the fund, and you will be allowed to claim a tax credit (or a deduction, if you itemize deductions) for such taxes.

Special Considerations for 529 Share Classes. In addition to the tax considerations discussed above, please note the following tax considerations that apply specifically to the ownership of the fund’s 529 share classes through a tuition program that qualifies under Internal Revenue Code Section 529.

The fund is an investment option under one or more tuition programs designed to qualify under Section 529 so that earnings on investments are not subject to federal income tax (to either a contributor to the tuition program or a designated beneficiary) until the earnings are withdrawn. Withdrawals of earnings that are used to pay “qualified higher education expenses” are tax-free for federal income tax purposes. State and local income taxes may still apply. These tax benefits are not available to 529 shares that are not owned through a qualifying Section 529 tuition program.

Withdrawals of earnings that are not used for the designated beneficiary’s qualified higher education expenses generally are subject not only to federal income tax but also to a 10% penalty tax (unless such amounts are transferred within sixty (60) days to another tuition program for the same designated beneficiary or another designated beneficiary who is a member of the family of the designated beneficiary with respect to which the distribution was made and certain other conditions are satisfied). The 10% penalty tax will not apply to distributions made under certain circumstances, including certain distributions made after the designated beneficiary dies, becomes disabled, or receives a scholarship or other tax-free payment for educational expenses that does not exceed the amount of the distribution. Distributions attributable to contributions to the tuition program (including the portion of any rollover from another tuition program that is attributable to contributions to that program) are not subject to tax.

You are urged to consult your own tax adviser for information about the federal, state, and local tax consequences of your investment in the fund’s 529 share classes.

Information about the Summary Prospectus, Prospectus, and SAI

Provision of Financial Reports and Summary Prospectuses

MFS Aggressive Growth Allocation Fund

telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

Additional Information on Fees and Expenses and Performance

Fees and Expenses

The annual fund operating expenses shown in “Fees and Expenses” are based on annualized expenses reported during the fund’s most recently completed fiscal year, and a weighted average of the total annual fund operating expenses and the fee charged (if any) by the fund(s) in which the fund invested during the fund’s most recently completed fiscal year, expressed as a percentage of a class’ average net assets during the period. The fund invests in Class R6 shares of the underlying funds. Annual fund operating expenses have not been adjusted to reflect the fund’s current asset size. In general, annual fund operating expenses, expressed as a percentage of a class’ average net assets, increase as the fund’s assets decrease. Annual fund operating expenses will likely vary from year to year.

Performance Information

From time to time, the fund may receive proceeds from litigation settlements, without which performance would be lower.

MFS Aggressive Growth Allocation Fund

Financial Highlights

The financial highlights are intended to help you understand a fund’s financial performance for the past five years. Certain information reflects financial results for a single fund share. The total returns in the financial highlights represent the rate by which an investor would have earned (or lost) on an investment in a fund (assuming reinvestment of all distributions) held for the entire period. This information has been audited by the fund’s independent registered public accounting firm, whose report, together with the fund’s financial statements, is included in the fund’s Annual Report to shareholders. The fund’s Annual Report is available upon request by contacting MFSC (please see back cover for address and telephone number). The fund’s independent registered public accounting firm is Ernst & Young LLP.

	Years ended 5/31
	2016			2015			2014			2013			2012

Class A
Net asset value, beginning of period	$	20.78		$	19.87		$	17.17		$	13.79		$	15.33
Income (loss) from investment operations
Net investment income (d)(l)	$	0.12		$	0.16		$	0.13		$	0.12		$	0.10
Net realized and unrealized gain (loss) on investments	(0.44		)	1.00			2.76			3.44			(1.44		)
Total from investment operations	$	(0.32	)	$	1.16		$	2.89		$	3.56		$	(1.34	)
Less distributions declared to shareholders
From net investment income	$	(0.31	)	$	(0.25	)	$	(0.19	)	$	(0.18	)	$	(0.20	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.99	)	$	(0.25	)	$	(0.19	)	$	(0.18	)	$	(0.20	)
Net asset value, end of period (x)	$	19.47		$	20.78		$	19.87		$	17.17		$	13.79
Total return (%) (r)(s)(t)(x)	(1.45		)	5.89			16.85			25.99			(8.70		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.40			0.40			0.37			0.38			0.33
Expenses after expense reductions (f)(h)	0.38			0.38			0.37			0.37			0.33
Net investment income (l)	0.63			0.80			0.70			0.80			0.70
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	785,986		$	778,633		$	742,788		$	539,351		$	433,117

	Years ended 5/31
	2016			2015			2014			2013			2012

Class B
Net asset value, beginning of period	$	20.46		$	19.55		$	16.90		$	13.56		$	15.05
Income (loss) from investment operations
Net investment income (loss) (d)(l)	$	(0.02	)	$	0.01		$	(0.01	)	$	0.01		$	(0.01	)
Net realized and unrealized gain (loss) on investments	(0.46		)	0.99			2.70			3.39			(1.40		)
Total from investment operations	$	(0.48	)	$	1.00		$	2.69		$	3.40		$	(1.41	)
Less distributions declared to shareholders
From net investment income	$	(0.14	)	$	(0.09	)	$	(0.04	)	$	(0.06	)	$	(0.08	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.82	)	$	(0.09	)	$	(0.04	)	$	(0.06	)	$	(0.08	)
Net asset value, end of period (x)	$	19.16		$	20.46		$	19.55		$	16.90		$	13.56
Total return (%) (r)(s)(t)(x)	(2.26		)	5.12			15.93			25.11			(9.37		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	1.15			1.14			1.12			1.13			1.08
Expenses after expense reductions (f)(h)	1.13			1.13			1.12			1.13			1.08
Net investment income (loss) (l)	(0.11		)	0.07			(0.03		)	0.05			(0.04		)
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	71,184		$	85,310		$	96,456		$	100,340		$	99,925

MFS Aggressive Growth Allocation Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class C
Net asset value, beginning of period	$	20.30		$	19.43		$	16.81		$	13.51		$	15.01
Income (loss) from investment operations
Net investment income (loss) (d)(l)	$	(0.02	)	$	0.01		$	(0.01	)	$	0.01		$	(0.01	)
Net realized and unrealized gain (loss) on investments	(0.45		)	0.97			2.70			3.37			(1.40		)
Total from investment operations	$	(0.47	)	$	0.98		$	2.69		$	3.38		$	(1.41	)
Less distributions declared to shareholders
From net investment income	$	(0.16	)	$	(0.11	)	$	(0.07	)	$	(0.08	)	$	(0.09	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.84	)	$	(0.11	)	$	(0.07	)	$	(0.08	)	$	(0.09	)
Net asset value, end of period (x)	$	18.99		$	20.30		$	19.43		$	16.81		$	13.51
Total return (%) (r)(s)(t)(x)	(2.24		)	5.08			16.01			25.05			(9.35		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	1.15			1.15			1.12			1.12			1.08
Expenses after expense reductions (f)(h)	1.13			1.13			1.12			1.12			1.08
Net investment income (loss) (l)	(0.12		)	0.07			(0.04		)	0.04			(0.05		)
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	282,953		$	294,608		$	265,993		$	195,777		$	148,481

	Years ended 5/31
	2016			2015			2014			2013			2012

Class I
Net asset value, beginning of period	$	21.09		$	20.16		$	17.41		$	13.98		$	15.53
Income (loss) from investment operations
Net investment income (d)(l)	$	0.18		$	0.22		$	0.18		$	0.17		$	0.13
Net realized and unrealized gain (loss) on investments	(0.46		)	1.01			2.80			3.48			(1.44		)
Total from investment operations	$	(0.28	)	$	1.23		$	2.98		$	3.65		$	(1.31	)
Less distributions declared to shareholders
From net investment income	$	(0.36	)	$	(0.30	)	$	(0.23	)	$	(0.22	)	$	(0.24	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(1.04	)	$	(0.30	)	$	(0.23	)	$	(0.22	)	$	(0.24	)
Net asset value, end of period (x)	$	19.77		$	21.09		$	20.16		$	17.41		$	13.98
Total return (%) (r)(s)(x)	(1.23		)	6.16			17.15			26.29			(8.42		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.15			0.15			0.12			0.12			0.08
Expenses after expense reductions (f)(h)	0.13			0.13			0.12			0.12			0.08
Net investment income (l)	0.89			1.06			0.94			1.05			0.93
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	62,542		$	64,751		$	58,061		$	45,150		$	29,816

MFS Aggressive Growth Allocation Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class 529A
Net asset value, beginning of period	$	20.66		$	19.76		$	17.08		$	13.72		$	15.24
Income (loss) from investment operations
Net investment income (d)(l)	$	0.11		$	0.16		$	0.13		$	0.12		$	0.09
Net realized and unrealized gain (loss) on investments	(0.45		)	0.98			2.73			3.42			(1.42		)
Total from investment operations	$	(0.34	)	$	1.14		$	2.86		$	3.54		$	(1.33	)
Less distributions declared to shareholders
From net investment income	$	(0.30	)	$	(0.24	)	$	(0.18	)	$	(0.18	)	$	(0.19	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.98	)	$	(0.24	)	$	(0.18	)	$	(0.18	)	$	(0.19	)
Net asset value, end of period (x)	$	19.34		$	20.66		$	19.76		$	17.08		$	13.72
Total return (%) (r)(s)(t)(x)	(1.54		)	5.84			16.78			25.93			(8.69		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.50			0.50			0.47			0.48			0.43
Expenses after expense reductions (f)(h)	0.42			0.42			0.41			0.42			0.38
Net investment income (l)	0.59			0.78			0.68			0.75			0.65
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	128,357		$	127,112		$	117,316		$	94,653		$	73,786

	Years ended 5/31
	2016			2015			2014			2013			2012

Class 529B
Net asset value, beginning of period	$	20.23		$	19.34		$	16.72		$	13.43		$	14.89
Income (loss) from investment operations
Net investment income (loss) (d)(l)	$	(0.03	)	$	0.00	(w)	$	(0.01	)	$	(0.00	)(w)	$	(0.01	)
Net realized and unrealized gain (loss) on investments	(0.44		)	0.97			2.67			3.34			(1.38		)
Total from investment operations	$	(0.47	)	$	0.97		$	2.66		$	3.34		$	(1.39	)
Less distributions declared to shareholders
From net investment income	$	(0.14	)	$	(0.08	)	$	(0.04	)	$	(0.05	)	$	(0.07	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.82	)	$	(0.08	)	$	(0.04	)	$	(0.05	)	$	(0.07	)
Net asset value, end of period (x)	$	18.94		$	20.23		$	19.34		$	16.72		$	13.43
Total return (%) (r)(s)(t)(x)	(2.23		)	5.05			15.91			24.93			(9.34		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	1.25			1.24			1.22			1.23			1.18
Expenses after expense reductions (f)(h)	1.18			1.18			1.17			1.17			1.13
Net investment income (loss) (l)	(0.15		)	0.02			(0.07		)	(0.01		)	(0.10		)
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	6,868		$	8,151		$	8,759		$	8,832		$	8,519

MFS Aggressive Growth Allocation Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class 529C
Net asset value, beginning of period	$	20.04		$	19.18		$	16.60		$	13.34		$	14.82
Income (loss) from investment operations
Net investment income (loss) (d)(l)	$	(0.03	)(w)	$	0.01		$	(0.02	)	$	(0.00	)(w)	$	(0.01	)
Net realized and unrealized gain (loss) on investments	(0.44		)	0.96			2.66			3.33			(1.39		)
Total from investment operations	$	(0.47	)	$	0.97		$	2.64		$	3.33		$	(1.40	)
Less distributions declared to shareholders
From net investment income	$	(0.16	)	$	(0.11	)	$	(0.06	)	$	(0.07	)	$	(0.08	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.84	)	$	(0.11	)	$	(0.06	)	$	(0.07	)	$	(0.08	)
Net asset value, end of period (x)	$	18.73		$	20.04		$	19.18		$	16.60		$	13.34
Total return (%) (r)(s)(t)(x)	(2.27		)	5.06			15.90			25.02			(9.42		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	1.25			1.25			1.22			1.22			1.18
Expenses after expense reductions (f)(h)	1.17			1.17			1.16			1.17			1.13
Net investment income (loss) (l)	(0.15		)	0.03			(0.08		)	(0.01		)	(0.10		)
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	37,772		$	37,784		$	35,650		$	28,527		$	22,437

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R1
Net asset value, beginning of period	$	20.03		$	19.14		$	16.55		$	13.28		$	14.76
Income (loss) from investment operations
Net investment income (loss) (d)(l)	$	(0.02	)	$	(0.02	)	$	(0.00	)(w)	$	0.01		$	(0.00	)(w)
Net realized and unrealized gain (loss) on investments	(0.44		)	0.99			2.64			3.31			(1.38		)
Total from investment operations	$	(0.46	)	$	0.97		$	2.64		$	3.32		$	(1.38	)
Less distributions declared to shareholders
From net investment income	$	(0.15	)	$	(0.08	)	$	(0.05	)	$	(0.05	)	$	(0.10	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.83	)	$	(0.08	)	$	(0.05	)	$	(0.05	)	$	(0.10	)
Net asset value, end of period (x)	$	18.74		$	20.03		$	19.14		$	16.55		$	13.28
Total return (%) (r)(s)(x)	(2.21		)	5.08			15.95			25.06			(9.36		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	1.15			1.15			1.12			1.13			1.08
Expenses after expense reductions (f)(h)	1.13			1.13			1.12			1.13			1.08
Net investment income (loss) (l)	(0.12		)	(0.11		)	(0.02		)	0.05			(0.03		)
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	17,908		$	20,596		$	18,849		$	18,793		$	20,186

MFS Aggressive Growth Allocation Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R2
Net asset value, beginning of period	$	20.38		$	19.48		$	16.84		$	13.53		$	15.03
Income (loss) from investment operations
Net investment income (d)(l)	$	0.08		$	0.10		$	0.08		$	0.09		$	0.06
Net realized and unrealized gain (loss) on investments	(0.45		)	0.99			2.70			3.37			(1.40		)
Total from investment operations	$	(0.37	)	$	1.09		$	2.78		$	3.46		$	(1.34	)
Less distributions declared to shareholders
From net investment income	$	(0.25	)	$	(0.19	)	$	(0.14	)	$	(0.15	)	$	(0.16	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.93	)	$	(0.19	)	$	(0.14	)	$	(0.15	)	$	(0.16	)
Net asset value, end of period (x)	$	19.08		$	20.38		$	19.48		$	16.84		$	13.53
Total return (%) (r)(s)(x)	(1.69		)	5.61			16.54			25.66			(8.86		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.65			0.64			0.62			0.63			0.58
Expenses after expense reductions (f)(h)	0.63			0.63			0.62			0.63			0.58
Net investment income (l)	0.40			0.51			0.46			0.56			0.46
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	82,546		$	94,097		$	119,055		$	106,825		$	94,686

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R3
Net asset value, beginning of period	$	20.62		$	19.72		$	17.05		$	13.69		$	15.23
Income (loss) from investment operations
Net investment income (d)(l)	$	0.12		$	0.16		$	0.13		$	0.12		$	0.08
Net realized and unrealized gain (loss) on investments	(0.45		)	0.99			2.73			3.42			(1.41		)
Total from investment operations	$	(0.33	)	$	1.15		$	2.86		$	3.54		$	(1.33	)
Less distributions declared to shareholders
From net investment income	$	(0.30	)	$	(0.25	)	$	(0.19	)	$	(0.18	)	$	(0.21	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(0.98	)	$	(0.25	)	$	(0.19	)	$	(0.18	)	$	(0.21	)
Net asset value, end of period (x)	$	19.31		$	20.62		$	19.72		$	17.05		$	13.69
Total return (%) (r)(s)(x)	(1.47		)	5.89			16.80			26.03			(8.68		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.40			0.40			0.37			0.38			0.33
Expenses after expense reductions (f)(h)	0.38			0.38			0.37			0.38			0.33
Net investment income (l)	0.65			0.82			0.71			0.79			0.55
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	158,309		$	174,355		$	164,977		$	128,498		$	97,526

MFS Aggressive Growth Allocation Fund

	Years ended 5/31
	2016			2015			2014			2013			2012

Class R4
Net asset value, beginning of period	$	20.85		$	19.93		$	17.22		$	13.81		$	15.35
Income (loss) from investment operations
Net investment income (d)(l)	$	0.16		$	0.24		$	0.19		$	0.14		$	0.13
Net realized and unrealized gain (loss) on investments	(0.44		)	0.98			2.75			3.49			(1.43		)
Total from investment operations	$	(0.28	)	$	1.22		$	2.94		$	3.63		$	(1.30	)
Less distributions declared to shareholders
From net investment income	$	(0.36	)	$	(0.30	)	$	(0.23	)	$	(0.22	)	$	(0.24	)
From net realized gain on investments	(0.68		)	—			—			—			—
Total distributions declared to shareholders	$	(1.04	)	$	(0.30	)	$	(0.23	)	$	(0.22	)	$	(0.24	)
Net asset value, end of period (x)	$	19.53		$	20.85		$	19.93		$	17.22		$	13.81
Total return (%) (r)(s)(x)	(1.24		)	6.18			17.11			26.47			(8.45		)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)(h)	0.14			0.15			0.12			0.13			0.08
Expenses after expense reductions (f)(h)	0.13			0.13			0.12			0.13			0.08
Net investment income (l)	0.80			1.21			1.00			0.88			0.95
Portfolio turnover	5			6			4			9			11
Net assets at end of period (000 omitted)	$	60,355		$	79,509		$	41,968		$	26,339		$	62,779

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(h) In addition to the fees and expenses which the fund bears directly, the fund indirectly bears a pro rata share of the fees and expenses of the underlying affiliated funds in which the fund invests. Accordingly, the expense ratio for the fund reflects only those fees and expenses borne directly by the fund. Because the underlying affiliated funds have varied expense and fee levels and the fund may own different proportions of the underlying affiliated funds at different times, the amount of fees and expenses incurred indirectly by the fund will vary.

(l) Recognition of net investment income by the fund may be affected by the timing of the declaration of dividends by the underlying affiliated funds in which the fund invests. The ratios and per share amounts do not include net investment income of the underlying affiliated funds in which the fund invests.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

(x) The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

MFS Aggressive Growth Allocation Fund

Appendix A - Description of Underlying Funds

Further information about each underlying fund, including a copy of an underlying fund’s most recent Prospectus, SAI, and Annual and Semi-Annual Reports, may be obtained on the fund’s Website at mfs.com , or by contacting MFSC.

MFS Commodity Strategy Fund

Investment Objective

The fund’s investment objective is to seek total return.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) seeks to achieve the fund’s objective by providing exposure to the commodities markets through investing in commodity-linked derivatives rather than investing directly in commodities. Commodities are assets with tangible properties, including oil, natural gas, agricultural products, and industrial and other precious metals.

MFS expects to gain exposure to the commodities markets by investing primarily in the MFS Commodity Strategy Portfolio, a wholly-owned and controlled subsidiary organized in the Cayman Islands (the “Subsidiary”). MFS may also gain exposure to the commodities markets by investing the fund’s assets directly in commodity-linked notes. The Subsidiary gains exposure to the commodities markets by investing in commodity-linked derivatives such as commodity-linked futures, options, and/or swaps. The Subsidiary is advised by MFS and has the same objective, strategies, and restrictions as the fund, except that MFS gains exposure to the commodities markets for the Subsidiary by investing primarily in commodity-linked futures, options, and/or swaps instead of commodity-linked notes. MFS may invest up to 25% of the fund’s assets (at the time of purchase) in the Subsidiary.

The fund’s direct and indirect investments in commodity-linked derivatives are leveraged (i.e., involves investment exposure greater than the amount of the investment). MFS expects the fund’s exposure to the commodities markets to be approximately equivalent to investing all of the fund’s investments in commodity-linked derivatives on an unleveraged basis.

MFS allocates the fund’s direct and indirect investments in commodity-linked derivatives among a variety of different commodities and commodity sectors based on proprietary quantitative models.

MFS generally invests substantially all of the fund’s assets not invested in the Subsidiary or commodity-linked notes in U.S. and foreign debt instruments. In addition, the Subsidiary may also invest in U.S. and foreign debt instruments. Debt instruments include corporate bonds, U.S. Government securities, foreign government securities, asset-backed securities, and other obligations to repay money borrowed. Of the fund’s direct and indirect investments in debt instruments, MFS generally invests substantially all of these investments in investment grade quality debt instruments.

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

The fund is a non-diversified fund. This means that MFS may invest a relatively large percentage of the fund’s assets in a single issuer or a small number of issuers.

Some portion of the fund’s and the Subsidiary’s assets may be held in cash and/or debt instruments due to asset coverage and collateral requirements for the fund’s and the Subsidiary’s investments in derivatives.

MFS uses a bottom-up investment approach to buying and selling debt investments for the fund. Debt investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate debt instruments may also be considered.

MFS Emerging Markets Equity Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in equity securities of issuers that are tied economically to emerging market countries. Emerging market countries are countries whose financial and capital markets are in the development phase and include countries located in Latin America, Asia, Africa, the Middle East, and developing countries of Europe, primarily Eastern Europe. MFS may also invest in equity securities of issuers that are not tied economically to emerging market countries.

Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS may invest the fund’s assets in companies of any size.

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

MFS normally allocates the fund’s investments across different industries and sectors, but MFS may invest a significant percentage of the fund’s assets in issuers in a single or small number of industries or sectors.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

MFS Global Real Estate Fund

Investment Objective

The fund’s investment objective is to seek total return.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in U.S. and foreign real estate-related investments.

MFS normally invests the fund’s assets primarily in equity securities.

MFS Aggressive Growth Allocation Fund

REITs, hybrid REITs and other U.S. and foreign real estate-related investments, including emerging market real estate-related investments.

MFS may invest the fund’s assets in real estate-related investments of any size. However, issuers of real estate-related investments tend to have small-to-medium market capitalizations.

MFS normally allocates the fund’s investments across different REIT managers and property types, but may from time to time focus the fund’s investments in any one or a few of these areas.

MFS normally allocates the fund’s investments across different countries and regions, but MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

MFS may invest a relatively large percentage of the fund’s assets in a single issuer or a small number of issuers.

MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers.

MFS Growth Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS International Growth Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets primarily in foreign equity securities, including emerging market equity securities. Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

MFS may invest the fund’s assets in companies of any size.

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

MFS International New Discovery Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with small to medium capitalizations.

MFS International Value Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS focuses on investing the fund’s assets in the stocks of companies it believes are undervalued compared to their intrinsic value (value companies). These companies may have stock prices that are higher relative to their earnings, dividends, assets, or other financial measures than companies generally considered value companies.

MFS may invest the fund’s assets in companies of any size.

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives

MFS Aggressive Growth Allocation Fund

primarily to increase or decrease currency exposure. Derivatives include futures, forward contracts, options, and swaps.

MFS Mid Cap Growth Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in issuers with medium market capitalizations. MFS generally defines medium market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Russell Midcap ® Growth Index over the last 13 months at the time of purchase. As of November 30, 2015, the range of the market capitalizations of the issuers in the Russell Midcap ® Growth Index was between $552 million and $31.87 billion.

MFS normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

MFS may invest the fund’s assets in foreign securities.

MFS Mid Cap Value Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in issuers with medium market capitalizations. MFS generally defines medium market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Russell Midcap ® Value Index over the last 13 months at the time of purchase. As of December 31, 2015, the range of the market capitalizations of the issuers in the Russell Midcap ® Value Index was between $381 million and $30.4 billion.

MFS normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks, real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).

MFS may invest the fund’s assets in foreign securities.

MFS New Discovery Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with small capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS New Discovery Value Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks, equity interests in real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with small capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS Research Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS Aggressive Growth Allocation Fund

growth potential compared to other companies (growth companies), in the stocks of companies it believes are undervalued compared to their perceived worth (value companies), or in a combination of growth and value companies.

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

A team of investment research analysts selects investments for the fund. MFS allocates the fund’s assets to analysts by broad market sectors.

MFS Research International Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.

In selecting investments for the fund, MFS is not constrained to any particular investment style. MFS may invest the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies), in the stocks of companies it believes are undervalued compared to their perceived worth (value companies), or in a combination of growth and value companies.

MFS may invest the fund’s assets in companies of any size.

A team of investment research analysts selects investments for the fund. MFS allocates the fund’s assets to analysts by broad market sectors.

MFS Value Fund

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Principal Investment Strategies

MFS focuses on investing the fund’s assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

Russell Indices

The Russell Midcap ® Growth Index and Russell Midcap ® Value Index are trademarks/service marks of the Frank Russell Company. Russell ® is a trademark of the Frank Russell Company.

MFS Aggressive Growth Allocation Fund

MFS Aggressive Growth Allocation Fund

If you want more information about MFS Aggressive Growth Allocation Fund, the following documents are available free upon request:

You can get free copies of the annual/semiannual reports, the SAI and other information about the fund, including current net asset values per share, and make inquiries about the fund, by contacting:

Internet: mfs.com

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

Telephone: 1-800-225-2606

Information about the fund (including its prospectus, SAI and shareholder reports) can be reviewed and copied at the:

U.S. Securities and Exchange Commission

Public Reference Room

Washington, DC 20549-1502

The fund’s Investment Company Act file number is 811-4492.

HOW TO CONTACT US

Web site	Account service and literature	Mailing address
mfs.com	Shareholders	MFS Service Center, Inc.
	1-800-225-2606	P.O. Box 55824
MFS TALK	Investment professionals	Boston, MA 02205-5824
1-800-637-8255	1-800-343-2829
24 hours a day	Retirement plan services	Overnight mail
	1-800-637-1255	MFS Service Center, Inc.
		c/o Boston Financial Data Services
		30 Dan Road
		Canton, MA 02021-2809

September 28, 2016

PROSPECTUS

MFS ® Blended Research ® Growth Equity Fund

The investment objective of the fund is to seek capital appreciation.

CLASS		TICKER SYMBOL
Class A		BRWAX
Class B		BRWBX
Class C		BRWCX
Class I		BRWJX
Class R1		BRWRX
Class R2		BRWSX
Class R3		BRWTX
Class R4		BRWUX
Class R6 (Formerly Class R5)		BRWVX

Table of contents

SUMMARY OF KEY INFORMATION	2
INVESTMENT OBJECTIVE, STRATEGIES, AND RISKS	4
MANAGEMENT OF THE FUND	6
DESCRIPTION OF SHARE CLASSES	6
HOW TO PURCHASE, REDEEM, AND EXCHANGE SHARES	10
OTHER INFORMATION	14
FINANCIAL HIGHLIGHTS	17

BRW-PRO-092816

MFS Blended Research Growth Equity Fund

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 7 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Share Class

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

5.75

None

Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)

1.00

% #

4.00

1.00

None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Share Class	A		B		C		I		R1		R2		R3		R4		R6
Management Fee	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%
Distribution and/or Service (12b-1) Fees	0.25	%	1.00	%	1.00	%	None		1.00	%	0.50	%	0.25	%	None		None
Other Expenses	5.32	%	5.32	%	5.32	%	5.32	%	5.32	%	5.32	%	5.32	%	5.32	%	5.31	%
Total Annual Fund Operating Expenses	5.97	%	6.72	%	6.72	%	5.72	%	6.72	%	6.22	%	5.97	%	5.72	%	5.71	%
Fee Reductions and/or Expense Reimbursements 1	(5.23	)%	(5.23	)%	(5.23	)%	(5.23	)%	(5.23	)%	(5.23	)%	(5.23	)%	(5.23	)%	(5.26	)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	0.74	%	1.49	%	1.49	%	0.49	%	1.49	%	0.99	%	0.74	%	0.49	%	0.45	%

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

1 Massachusetts Financial Services Company has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.74% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.49% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.49% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 0.99% of the class’ average daily net assets annually for Class R2 shares, and 0.45% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

MFS Blended Research Growth Equity Fund

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.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR		3 YEARS		5 YEARS		10 YEARS
Class A Shares	$	646	$	1,808	$	2,948	$	5,701
Class B Shares assuming
redemption at end of period	$	552	$	1,819	$	3,033	$	5,821
no redemption at end of period	$	152	$	1,519	$	2,840	$	5,821
Class C Shares assuming
redemption at end of period	$	252	$	1,519	$	2,840	$	5,948
no redemption at end of period	$	152	$	1,519	$	2,840	$	5,948
Class I Shares	$	50	$	1,237	$	2,407	$	5,259
Class R1 Shares	$	152	$	1,519	$	2,840	$	5,948
Class R2 Shares	$	101	$	1,379	$	2,626	$	5,613
Class R3 Shares	$	76	$	1,308	$	2,517	$	5,439
Class R4 Shares	$	50	$	1,237	$	2,407	$	5,259
Class R6 Shares	$	46	$	1,232	$	2,400	$	5,250

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. For the period from the fund’s commencement of operations on September 15, 2015 to the fund’s fiscal year end of May 31, 2016, the fund’s portfolio turnover rate was 28% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in equity securities.

Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers to determine a fundamental rating for an issuer. MFS uses quantitative analysis to determine a quantitative rating for an issuer. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 2% compared to the Russell 1000 ® Growth Index (the “Index”). Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

Principal Risks

The principal risks of investing in the fund are:

Investment Strategy Risk: There is no assurance that the fund will meet its target predicted tracking error over the long term or for any year or period of years, or that the fund’s predicted tracking error and actual tracking error will be similar. The fund’s strategy to target a predicted tracking error of approximately 2% compared to the Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS fundamental research is not available for all issuers.

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Investment Selection Risk: MFS’ investment analysis, its development and use of quantitative models, and its selection of

MFS Blended Research Growth Equity Fund

investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. Investments selected using quantitative models may not produce the intended results due to the factors used in the models, the weight placed on each factor in the models, changing sources of market return, and technical issues in the design, development, implementation, and maintenance of the models (e.g., incomplete or inaccurate data, programming or other software issues, and technology failures).

Performance Information

The bar chart and performance table are not included because the fund has not had a full calendar year of operations.

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager	Since	Title
Matthew W. Krummell	2015	Investment Officer of MFS
James C. Fallon	2015	Investment Officer of MFS
Jonathan W. Sage	2015	Investment Officer of MFS
John E. Stocks	2015	Investment Officer of MFS

Purchase and Sale of Fund Shares

The fund’s initial and subsequent investment minimums generally are as follows:

Class

Initial Minimum

Subsequent Minimum

Class A, Class B, Class C

None – automatic investment plans and certain asset-based fee programs

$25 – employer-sponsored retirement plans

$250 – Traditional and Roth IRAs

$1,000 – other accounts

$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives

None – other purchases

Class I, Class R1, Class R2, Class R3, Class R4, Class R6

None

Taxes

Payments to Broker/Dealers and Other Financial Intermediaries

Investment Objective, Strategies, and Risks

Investment Objective

The fund’s investment objective is to seek capital appreciation. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

MFS normally invests at least 80% of the fund’s net assets in equity securities.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies). Growth companies tend to have stock prices that are high relative to their earnings, dividends, book value, or other financial measures.

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers and their potential in light of their financial condition and market, economic, political, and regulatory conditions to determine a fundamental rating for an issuer. Factors considered may include analysis of an issuer’s earnings, cash flows, competitive position, and management ability. MFS uses quantitative analysis, including quantitative models that systematically evaluate an issuer’s valuation, price and earnings momentum, earnings quality, and other factors, to determine a quantitative rating for an issuer. When MFS quantitative research is available but MFS fundamental research is not available, MFS considers the issuer to have a neutral fundamental rating. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 2% compared to the Index. Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period. A higher tracking error means that the differences between the fund’s returns and the Index’s returns have varied more over time while a lower tracking error means the differences between the fund’s returns and the Index’s returns have varied less over time.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

MFS Blended Research Growth Equity Fund

Principal Investment Type

The principal investment type in which the fund may invest is:

Equity Securities: Equity securities represent an ownership interest, or the right to acquire an ownership interest, in a company or other issuer. Different types of equity securities provide different voting and dividend rights and priorities in the event of bankruptcy of the issuer. Equity securities include common stocks, preferred stocks, securities convertible into stocks, equity interests in real estate investment trusts (REITs), and depositary receipts for such securities.

Principal Risks

The share price of the fund will change daily based on changes in market, economic, industry, political, regulatory, geopolitical, and other conditions. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Foreign Risk: Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. Political, social, and economic developments, U.S. and foreign government action such as the imposition of currency or capital controls, economic and trade sanctions or embargoes, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Economies and financial markets are becoming more connected, which increases the likelihood that conditions in one country or region can adversely impact issuers in different countries and regions. Less stringent regulatory, accounting, and disclosure requirements for issuers and markets are more common in certain foreign countries. Enforcing legal rights can be difficult, costly, and slow in certain foreign countries, and can be particularly difficult against foreign governments. Changes in currency exchange rates can affect the U.S. dollar value of foreign currency investments and investments denominated in foreign currencies. Additional risks of foreign investments include trading, settlement, custodial, and other operational risks, and withholding and other taxes. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, and other conditions than the U.S. market.

Other Investment Strategies and Risks

MFS Blended Research Growth Equity Fund

Management of the Fund

Investment Adviser

The management fee set forth in the Investment Advisory Agreement is 0.40% of the fund’s average daily net assets annually up to $1 billion; 0.375% of the fund’s average daily net assets annually in excess of $1 billion and up to $2.5 billion; and 0.35% of the fund’s average daily net assets annually in excess of $2.5 billion.

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the period from September 15, 2015 to May 31, 2016, this management fee reduction amounted to less than 0.01% of the fund’s average daily net assets.

MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.74% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.49% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.49% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 0.99% of the class’ average daily net assets annually for Class R2 shares, and 0.45% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

A discussion regarding the basis for the Board of Trustees’ approval of the Investment Advisory Agreement is available in the fund’s semiannual report for the period ended November 30, 2015.

Disclosure of Portfolio Holdings . The fund has established a policy with respect to the disclosure of fund portfolio holdings. A description of this policy is provided in the SAI.

Information		Approximate Date of Posting To Web Site
Fund’s top 10 holdings as of each month’s end		14 days after month end
Fund’s full holdings as of each month’s end		24 days after month end

Holdings also include short positions, if any.

Portfolio Manager(s)

Portfolio Manager	Primary Role	Five Year History
Matthew W. Krummell	Lead Portfolio Manager	Employed in the investment area of MFS since 2001
James C. Fallon	Portfolio Manager	Employed in the investment area of MFS since 1999
Jonathan W. Sage	Portfolio Manager	Employed in the investment area of MFS since 2000
John E. Stocks	Portfolio Manager	Employed in the investment area of MFS since 2001

Administrator

Distributor

MFS Fund Distributors, Inc. (“MFD”), a wholly owned subsidiary of MFS, is the distributor of shares of the fund.

Shareholder Servicing Agent

Description of Share Classes

MFS Blended Research Growth Equity Fund

consult with your financial intermediary to help you determine which class is most appropriate for you.

Class I shares generally are available only to the following eligible investors:

· certain retirement plans established for the benefit of employees and former employees of MFS or its affiliates;

· defined benefit retirement plans, endowments or foundations;

· bank trust departments or law firms acting as trustee or manager for trust accounts;

· investors who purchase shares through asset-based fee programs available through financial intermediaries;

In addition, MFD may accept, in its sole discretion, investments in Class I shares from purchasers not listed above.

Class C shareholders may be able to convert their Class C shares not subject to a CDSC to Class I shares of the fund if they satisfy eligibility requirements of Class I shares.

Sales Charges and Waivers or Reductions

You may be subject to an initial sales charge when you purchase Class A shares, or a CDSC when you redeem Class A, Class B, or Class C shares. These sales charges are paid to MFD.

Class A Shares. You may purchase Class A shares at the offering price (which includes the applicable initial sales charge).

The amount of the initial sales charge you pay when you buy Class A shares differs depending upon the amount you invest, as follows:

	INITIAL SALES CHARGE AS PERCENTAGE OF:
Amount of Purchase	GROSS PURCHASE AMOUNT (OFFERING PRICE*)		NET AMOUNT INVESTED
Less than $50,000	5.75	%	6.10	%
$50,000 but less than $100,000	4.75	%	4.99	%
$100,000 but less than $250,000	3.75	%	3.90	%
$250,000 but less than $500,000	2.75	%	2.83	%
$500,000 but less than $1,000,000	2.00	%	2.04	%
$1,000,000 or more	None		None

The CDSC is imposed according to the following schedule:

Year of redemption after purchase		1st		2nd		3rd		4th		5th		6th		7th
Contingent deferred sales charge		4	%	4	%	3	%	3	%	2	%	1	%	0	%

MFS Blended Research Growth Equity Fund

Class I Shares. Eligible investors may purchase Class I shares at net asset value without an initial sales charge or a CDSC upon redemption.

	INVESTMENTS ELIGIBLE FOR:
Program	WAIVED INITIAL SALES CHARGE	REDUCED INITIAL SALES CHARGE	WAIVED CDSC
Letter of Intent		X
Right of Accumulation		X
Automatic Exchange Plan	X*
Exchange Privilege	X*
Systematic Withdrawal Plan			X**
Distribution Reinvestment	X
Distribution Investment Program	X
Reinstatement Privilege	X
Other Sales Charge Waivers	X		X

* Investments under the Automatic Exchange Plan or certain other exchanges may be subject to a sales charge in certain cases.

** Limited for Class A, Class B, and Class C shares.

Eligible accounts that you may link under an LOI and ROA are:

· Individual accounts;

· Joint accounts;

· Trust accounts of which you, your spouse (or legal equivalent under applicable state law), or child under the age of 21 is the grantor;

· MFS 529 College Savings Plan accounts;

· Certain single-participant retirement plan accounts;

· Certain Individual Retirement Accounts;

· Uniform Gifts/Transfers to Minor Acts accounts; and

· Accounts held in the name of your financial intermediary on your behalf.

It is your responsibility to inform the broker/dealer for each current purchase of any accounts held with the MFS

MFS Blended Research Growth Equity Fund

funds that you believe are eligible to be linked under an LOI or an ROA. If you have not designated a broker/dealer, you should inform MFSC directly of any accounts held with the MFS funds that you believe are eligible to be linked under an LOI or an ROA. You should provide your financial intermediary (or MFSC if you have not designated a broker/dealer) with certain supporting information at the time of each purchase regarding accounts held with the MFS funds that are eligible to be combined for purposes of an LOI or ROA. Such information may include shareholder identification numbers or applicable account numbers or account statements. Your financial intermediary is responsible for taking into account this information about accounts eligible to be combined when transmitting your purchase order to the fund.

· Systematic Withdrawal Plan. If you have a balance of at least $5,000 in your account in the fund, you may elect to receive (or designate someone else to receive) regular periodic payments (of at least $50 if by check) through an automatic redemption of Class A, Class B, Class C, or Class I shares. For Class A, Class B, or Class C shares, you may incur a CDSC when Class A, Class B, or Class C shares are redeemed under the plan (or plans if more than one plan is established) if greater than 10% of the value of your account is withdrawn under the plan(s) in any one year (determined at the time of your first withdrawal under the plan(s), or January 4, 2016, with respect to Class A shares, January 3, 2007, with respect to Class B shares, or January 2, 2008, with respect to Class C shares, whichever is later). The applicable CDSC will be prorated across all of your payments taken in the one year period.

· Distribution Reinvestment. You may automatically reinvest dividend and capital gain distributions in the same fund without paying an initial sales charge.

Any CDSC paid upon the redemption of Class B shares will not be credited to your account.

Shares acquired through reinvestment of distributions are not subject to a CDSC.

Distribution and Service Fees

CLASS	MAXIMUM DISTRIBUTION FEE		MAXIMUM SERVICE FEE		MAXIMUM TOTAL DISTRIBUTION AND SERVICE FEE
Class A	0.00	%	0.25	%	0.25	%
Class B	0.75	%	0.25	%	1.00	%
Class C	0.75	%	0.25	%	1.00	%
Class R1	0.75	%	0.25	%	1.00	%
Class R2	0.25	%	0.25	%	0.50	%
Class R3	0.00	%	0.25	%	0.25	%

These fees are paid out of fund assets of the applicable class of shares. Because these fees are an ongoing expense of the fund, they

MFS Blended Research Growth Equity Fund

increase the cost of your investment over time and may cost you more than other types of sales charges.

The fund has not adopted a Rule 12b-1 plan with respect to its Class I, Class R4, or Class R6 shares.

Financial Intermediary Compensation

Financial intermediaries may receive up-front commissions of up to the following percentage amounts for sales of the following share classes:

SHARE CLASS	UP FRONT COMMISSION AS A PERCENTAGE OF OFFERING PRICE
Class A	5.75	%
Class B	3.75	%
Class C	1.00	%

How To Purchase, Redeem, and Exchange Shares

How to Purchase Shares

MFS Blended Research Growth Equity Fund

Class A, Class B, and Class C Shares. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

Class I Shares. You can establish an account through your MFD representative, by having your financial intermediary process your purchase, or by contacting MFSC directly.

Additional Purchases

You may purchase additional shares through your financial intermediary or MFSC.

· Additional Purchases Directly Through MFSC.

· Mail. You may purchase additional shares by mailing a check with your investment instructions to MFSC.

· Wire. To purchase additional shares by wire, call MFSC for instructions.

How to Redeem Shares

Your financial intermediary is responsible for transmitting your redemption order to the fund in proper form and in a timely manner. MFSC reserves the right to reject any redemption request that is not in proper form. The specific requirements for proper form depend on the type of account and transaction and the method of redemption; contact MFSC if you have questions about your particular circumstances. A redemption order in an amount less than or equal to the value of your account (other than an exchange) is considered to be in proper form only with respect to shares in your account for which payment has been received and collected. A new redemption order must be submitted if you wish to redeem your shares for which payment had not been received and collected at the time the prior redemption order was received by the fund. Receiving and collecting payment can take up to seven business days after a purchase. In certain circumstances, you will need to have your signature guaranteed and/or submit additional documentation to redeem your shares. In general, no signature guarantee is required for a redemption order for up to $100,000 that is signed by all owners or fiduciaries identified in the account registration, paid as registered, and mailed to the address of record. However, if you have changed your address of record within 30 days of your redemption order, a signature guarantee may be required.

You may redeem your shares either by having your financial intermediary process your redemption or by contacting MFSC directly.

Redeeming Directly Through MFSC.

MFS Blended Research Growth Equity Fund

proceeds sent to your bank account. Telephone redemptions are not available for certain types of accounts.

How to Exchange Shares

An exchange involves the redemption of shares of one fund and the purchase of shares of another fund.

You can exchange your Class A shares and your Class I shares for shares of the MFS U.S. Government Money Market Fund, if available, according to the terms of such fund’s prospectus.

Other Considerations

Disruptive Trading

MFS Blended Research Growth Equity Fund

determines its net asset value. The fund’s use of fair valuation can serve to reduce arbitrage opportunities available to short-term traders, but there is no assurance that the fund’s fair valuation policies and procedures will prevent dilution of the fund’s net asset value by short-term traders.

MFSC’s ability to monitor and deter frequent trading in omnibus accounts depends on, among other factors, the frequency with which MFSC requests underlying shareholder account data from

MFS Blended Research Growth Equity Fund

omnibus accounts. MFSC expects to request underlying shareholder data based on its assessment of the likelihood of frequent trading by underlying shareholders among other factors. MFSC expects to request underlying shareholder data from Waived Financial Intermediaries more frequently than from other financial intermediaries. There is no assurance that MFSC will request data with sufficient frequency to detect or prevent frequent trading in omnibus accounts effectively.

Other Information

Valuation

In addition, investments may be valued at fair value if MFS determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as a foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, foreign equity securities may often be valued at fair value. MFS generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Distributions

The fund intends to declare and pay any dividends to shareholders at least annually.

Any capital gains are distributed at least annually.

Distribution Options

The following distribution options are generally available:

· Dividend and capital gain distributions automatically reinvested in additional shares (this option will be assigned if no other option is specified) ;

· Dividend distributions in cash; capital gain distributions automatically reinvested in additional shares;

· Dividend and capital gain distributions in cash; or

· Dividend and capital gain distributions automatically reinvested into the same class of shares of another MFS Fund.

Not all options are available for every class or every account.

MFS Blended Research Growth Equity Fund

Dividends and capital gain distributions for Class R1, Class R2, Class R3, Class R4, and Class R6 shares automatically will be reinvested in additional shares of the fund.

Tax Considerations

Any gain resulting from the redemption, sale, or exchange of your shares will generally also be subject to tax.

The fund’s investments in foreign securities may be subject to foreign withholding or other taxes, which will decrease the fund’s return on those securities; you generally are not expected to be eligible to claim a credit (or a deduction, if you itemize deductions) for such amounts on your federal income tax return.

Information about the Summary Prospectus, Prospectus, and SAI

Provision of Financial Reports and Summary Prospectuses

Additional Information on Fees and Expenses and Performance

Fees and Expenses

Performance Information of Similarly-Managed Accounts

The following table presents the past performance of the MFS Blended Research - Large Cap Growth Composite (the “Composite”), which consists of accounts advised or sub-advised by MFS. Performance was calculated using a methodology which complies with the calculation requirements of the Global Investment Performance Standards ® (GIPS). The table also shows the average annual total return for Russell 1000 ® Growth Index, a broad-based securities market index (“Index”). The Composite is composed of all fee paying accounts under discretionary management by MFS that have investment objectives, policies, and strategies substantially similar to those of the fund. Likewise, the accounts that make up the Composite have the same portfolio management team as the fund. The gross performance data shown for the Composite does not reflect the deduction of investment advisory fees paid by the accounts composing the Composite and certain other expenses which would be applicable to mutual funds. The net performance data may be more relevant to potential investors in the fund in their analysis of the historical experience of MFS in managing portfolios

MFS Blended Research Growth Equity Fund

with investment objectives, policies, and strategies substantially similar to those of the fund. The Composite returns and the Index returns are calculated net of withholding taxes on dividends, interest, and capital gains. Net returns for the Composite are a net of the maximum applicable investment management fees charged by MFS for accounts managed in this strategy. The table also includes the performance of the Composite as adjusted for the expenses (on a percentage basis) that are expected to be borne by shareholders of each class of the fund, net of any fee reduction and/or reimbursement, as reflected in the “Annual Fund Operating Expenses” table. Fees and expenses of the fund differ from those used to calculate the net performance of the Composite.

The historical performance of the Composite is not, and is not a substitute for, the performance of the fund and is not necessarily indicative of the fund’s future results. You should not assume that the fund will have the same future performance as the Composite. Future performance of the fund may be greater or less than the performance of the Composite due to, among other things, differences in fees, expenses, asset size, and cash flows. The fund’s actual performance may vary significantly from the past performance of the Composite. Also, the accounts composing the Composite are not subject to the investment limitations, diversification requirements, and other restrictions imposed by the Investment Company Act of 1940 and the Internal Revenue Code or the fund’s fundamental investment restrictions. If these limitations, requirements, and restrictions were applicable to the accounts in the Composite, they may have had an adverse effect on the performance results of the Composite.

Average Annual Total Returns

(for the Periods Ended December 31, 2015)

	1 YEAR		3 YEARS		5 YEARS		Since 1- 1-2008 1
Composite (net)	4.78	%	17.44	%	14.37	%	8.66	%
Adjusted for Class A Expenses with initial Sales charge of 5.75% 2	(1.68	)%	14.69	%	12.58	%	7.43	%
Adjusted for Class B Expenses 2	3.54	%	16.11	%	13.08	%	7.43	%
Adjusted for Class B Expenses with CDSC (Declining over seven years from 4% to 0%) 2	(0.46	)%	15.36	%	12.83	%	7.43	%
Adjusted for Class C Expenses 2	3.54	%	16.11	%	13.08	%	7.43	%
Adjusted for Class C Expenses with CDSC (1% for 12 months) 2	2.54	%	16.11	%	13.08	%	7.43	%
Adjusted for Class I Expenses 2	4.58	%	17.26	%	14.20	%	8.50	%
Adjusted for Class R1 Expenses 2	3.54	%	16.11	%	13.08	%	7.43	%
Adjusted for Class R2 Expenses 2	4.06	%	16.69	%	13.64	%	7.96	%
Adjusted for Class R3 Expenses 2	4.32	%	16.97	%	13.92	%	8.23	%
Adjusted for Class R4 Expenses 2	4.58	%	17.26	%	14.20	%	8.50	%
Adjusted for Class R6 Expenses 2	4.62	%	17.31	%	14.25	%	8.54	%
Composite (gross)	5.09	%	17.83	%	14.76	%	9.03	%
Russell 1000 ® Growth Index	5.67	%	16.83	%	13.53	%	8.06	%

1 Inception date of the Composite.

2 Gross returns of the Composite have been adjusted to reflect the expenses (on a percentage basis) that are expected to be borne by shareholders of each class of shares of the fund, net of any waiver and/or reimbursement, as reflected in the “Annual Fund Operating Expenses” table. The returns reflect the impact of maximum sales charges you may be required to pay upon the purchase or redemption of the fund’s shares.

The Russell 1000 ® Growth Index is a trademark/service mark of the Frank Russell Company. Russell ® is a trademark of the Frank Russell Company.

MFS Blended Research Growth Equity Fund

Financial Highlights

The financial highlights are intended to help you understand the fund’s financial performance for the past five years (or, if shorter, the period of operation). Certain information reflects financial results for a single fund share. The total returns in the financial highlights represent the rate by which an investor would have earned (or lost) on an investment in the fund (assuming reinvestment of all distributions) held for the entire period. This information (with the exception of the semi-annual period ended November 30, 2015) has been audited by the fund’s independent registered public accounting firm, whose report, together with the fund’s financial statements, is included in the fund’s Annual Report to shareholders. The fund’s Annual Report and Semiannual Report are available upon request by contacting MFSC (please see back cover for address and telephone number). The financial statements contained in the Annual Report and Semiannual Report are incorporated by reference into the SAI. The fund’s independent registered public accounting firm is Deloitte & Touche LLP.

	Period ended 5/31/2016(c)

Class A
Net asset value, beginning of period	$	10.00
I ncome (loss) from investment operations
Net investment income (d)	$	0.06
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.28
Less distributions declared to shareholders
From net investment income	$	(0.03	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.03	)
Net asset value, end of period (x)	$	10.25
Total return (%) (r)(s)(t)(x)	2.81		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	5.24		(a)
Expenses after expense reductions (f)	0.69		(a)
Net investment income	0.82		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	352

	Period ended 5/31/2016(c)

Class B
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	(0.00	)(w)
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.22
Less distributions declared to shareholders
From net investment income	$	(0.00	)(w)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.00	)(w)
Net asset value, end of period (x)	$	10.22
Total return (%) (r)(s)(t)(x)	2.27		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.82		(a)
Expenses after expense reductions (f)	1.46		(a)
Net investment income	0.01		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	113

MFS Blended Research Growth Equity Fund

	Period ended 5/31/2016(c)

Class C
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	(0.00	)(w)
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.22
Less distributions declared to shareholders
From net investment income	$	(0.00	)(w)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.00	)(w)
Net asset value, end of period (x)	$	10.22
Total return (%) (r)(s)(t)(x)	2.26		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.92		(a)
Expenses after expense reductions (f)	1.46		(a)
Net investment income	0.02		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	62

	Period ended 5/31/2016(c)

Class I
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.08
Net realized and unrealized gain (loss) on investments and foreign currency	0.21
Total from investment operations	$	0.29
Less distributions declared to shareholders
From net investment income	$	(0.03	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.03	)
Net asset value, end of period (x)	$	10.26
Total return (%) (r)(s)(x)	2.97		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	4.67		(a)
Expenses after expense reductions (f)	0.46		(a)
Net investment income	1.06		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	286

MFS Blended Research Growth Equity Fund

	Period ended 5/31/2016(c)

Class R1
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	(0.00	)(w)
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.22
Less distributions declared to shareholders
From net investment income	$	(0.00	)(w)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.00	)(w)
Net asset value, end of period (x)	$	10.22
Total return (%) (r)(s)(x)	2.26		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	7.04		(a)
Expenses after expense reductions (f)	1.46		(a)
Net investment income	0.01		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	51

	Period ended 5/31/2016(c)

Class R2
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.26
Less distributions declared to shareholders
From net investment income	$	(0.02	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.02	)
Net asset value, end of period (x)	$	10.24
Total return (%) (r)(s)(x)	2.61		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.54		(a)
Expenses after expense reductions (f)	0.96		(a)
Net investment income	0.51		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	51

MFS Blended Research Growth Equity Fund

	Period ended 5/31/2016(c)

Class R3
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.05
Net realized and unrealized gain (loss) on investments and foreign currency	0.23
Total from investment operations	$	0.28
Less distributions declared to shareholders
From net investment income	$	(0.03	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.03	)
Net asset value, end of period (x)	$	10.25
Total return (%) (r)(s)(x)	2.79		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.29		(a)
Expenses after expense reductions (f)	0.71		(a)
Net investment income	0.76		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	51

	Period ended 5/31/2016(c)

Class R4
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.07
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.29
Less distributions declared to shareholders
From net investment income	$	(0.03	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.03	)
Net asset value, end of period (x)	$	10.26
Total return (%) (r)(s)(x)	2.97		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.04		(a)
Expenses after expense reductions (f)	0.46		(a)
Net investment income	1.01		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	51

MFS Blended Research Growth Equity Fund

	Period ended 5/31/2016(c)

Class R5
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.07
Net realized and unrealized gain (loss) on investments and foreign currency	0.22
Total from investment operations	$	0.29
Less distributions declared to shareholders
From net investment income	$	(0.03	)
From net realized gain on investments	(0.00		)(w)
Total distributions declared to shareholders	$	(0.03	)
Net asset value, end of period (x)	$	10.26
Total return (%) (r)(s)(x)	2.97		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	5.80		(a)
Expenses after expense reductions (f)	0.45		(a)
Net investment income	1.01		(a)
Portfolio turnover	28		(n)
Net assets at end of period (000 omitted)	$	2,853

(a) Annualized.

(c) For the period from the commencement of the fund’s investment operations, September 15, 2015, through the stated period end.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

MFS Blended Research Growth Equity Fund

MFS Blended Research Growth Equity Fund

If you want more information about MFS Blended Research Growth Equity Fund, the following documents are available free upon request:

You can get free copies of the annual/semiannual reports, the SAI and other information about the fund, including current net asset values per share, and make inquiries about the fund, by contacting:

Internet: mfs.com

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

Telephone: 1-800-225-2606

Information about the fund (including its prospectus, SAI and shareholder reports) can be reviewed and copied at the:

U.S. Securities and Exchange Commission

Public Reference Room

Washington, DC 20549-1502

The fund’s Investment Company Act file number is 811-4492.

HOW TO CONTACT US

Web site	Account service and literature	Mailing address
mfs.com	Shareholders	MFS Service Center, Inc.
	1-800-225-2606	P.O. Box 55824
MFS TALK	Investment professionals	Boston, MA 02205-5824
1-800-637-8255	1-800-343-2829
24 hours a day	Retirement plan services	Overnight mail
	1-800-637-1255	MFS Service Center, Inc.
		c/o Boston Financial Data Services
		30 Dan Road
		Canton, MA 02021-2809

September 28, 2016

PROSPECTUS

MFS ® Blended Research ® Small Cap Equity Fund

The investment objective of the fund is to seek capital appreciation.

CLASS		TICKER SYMBOL
Class A		BRSDX
Class B		BRSBX
Class C		BRSHX
Class I		BRSJX
Class 529A		BRSNX
Class 529B		BRSQX
Class 529C		BRSWX
Class R1		BRSPX
Class R2		BRSSX
Class R3		BRSTX
Class R4		BRSUX
Class R6 (Formerly Class R5)		BRSYX

Table of contents

SUMMARY OF KEY INFORMATION	2
INVESTMENT OBJECTIVE, STRATEGIES, AND RISKS	4
MANAGEMENT OF THE FUND	6
DESCRIPTION OF SHARE CLASSES	7
HOW TO PURCHASE, REDEEM, AND EXCHANGE SHARES	11
OTHER INFORMATION	15
FINANCIAL HIGHLIGHTS	19

BRS-PRO-092816

MFS Blended Research Small Cap Equity Fund

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 8 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Share Class

529A

B AND
529B

C AND
529C

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

5.75

None

Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)

1.00

% #

None

4.00

1.00

None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Share Class	A		B		C		I		529A		529B		529C		R1		R2		R3		R4		R6
Management Fee	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%	0.65	%
Distribution and/or Service (12b-1) Fees	0.25	%	1.00	%	1.00	%	None		0.25	%	1.00	%	1.00	%	1.00	%	0.50	%	0.25	%	None		None
Other Expenses	5.49	%	5.49	%	5.49	%	5.49	%	5.59	%	5.59	%	5.59	%	5.49	%	5.49	%	5.49	%	5.49	%	5.48	%
Total Annual Fund Operating Expenses	6.39	%	7.14	%	7.14	%	6.14	%	6.49	%	7.24	%	7.24	%	7.14	%	6.64	%	6.39	%	6.14	%	6.13	%
Fee Reductions and/or Expense Reimbursements 1	(5.40	)%	(5.40	)%	(5.40	)%	(5.40	)%	(5.45	)%	(5.45	)%	(5.45	)%	(5.40	)%	(5.40	)%	(5.40	)%	(5.40	)%	(5.43	)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	0.99	%	1.74	%	1.74	%	0.74	%	1.04	%	1.79	%	1.79	%	1.74	%	1.24	%	0.99	%	0.74	%	0.70	%

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

1 MFS Fund Distributors, Inc., has agreed in writing to waive the program management fee for each of the fund’s Class 529A, Class 529B, and Class 529C shares to 0.05% of the class’ average daily net assets attributable to each share class annually. This written agreement will expire on September 30, 2017, unless MFS Fund Distributors, Inc., elects to extend the waiver. Massachusetts Financial Services Company has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.99% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.74% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.74% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 1.24% of the class’ average daily net assets annually for Class R2 shares, 0.70% of the class’ average daily net assets annually for Class R6 shares, 1.04% of the class’ average daily net assets annually for Class 529A shares, and 1.79% of the class’ average daily net asset annually for each of Class 529B and Class 529C shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

MFS Blended Research Small Cap Equity Fund

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.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR		3 YEARS		5 YEARS		10 YEARS
Class A Shares	$	670	$	1,906	$	3,107	$	5,967
Class B Shares assuming
redemption at end of period	$	577	$	1,917	$	3,191	$	6,085
no redemption at end of period	$	177	$	1,620	$	3,002	$	6,085
Class C Shares assuming
redemption at end of period	$	277	$	1,620	$	3,002	$	6,207
no redemption at end of period	$	177	$	1,620	$	3,002	$	6,207
Class I Shares	$	76	$	1,341	$	2,578	$	5,550
Class 529A Shares	$	675	$	1,928	$	3,144	$	6,028
Class 529B Shares assuming
redemption at end of period	$	582	$	1,939	$	3,228	$	6,145
no redemption at end of period	$	182	$	1,643	$	3,040	$	6,145
Class 529C Shares assuming
redemption at end of period	$	282	$	1,643	$	3,040	$	6,266
no redemption at end of period	$	182	$	1,643	$	3,040	$	6,266
Class R1 Shares	$	177	$	1,620	$	3,002	$	6,207
Class R2 Shares	$	126	$	1,482	$	2,793	$	5,888
Class R3 Shares	$	101	$	1,412	$	2,686	$	5,721
Class R4 Shares	$	76	$	1,341	$	2,578	$	5,550
Class R6 Shares	$	72	$	1,336	$	2,572	$	5,541

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. For the period from the fund’s commencement of operations on September 15, 2015 to the fund’s fiscal year end of May 31, 2016, the fund’s portfolio turnover rate was 47% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in equity securities of issuers with small market capitalizations. MFS generally defines small market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Russell 2000 ® Index (the “Index”) over the last 13 months at the time of purchase. As of August 31, 2016, the range of the market capitalizations of the issuers in the Index was between $10.7 million and $4.7 billion.

Equity securities include common stocks, equity interests in real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers to determine a fundamental rating for an issuer. MFS uses quantitative analysis to determine a quantitative rating for an issuer. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 3% compared to the Index. Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

Principal Risks

The principal risks of investing in the fund are:

Investment Strategy Risk: There is no assurance that the fund will meet its target predicted tracking error over the long term or for any year or period of years, or that the fund’s predicted tracking error and actual tracking error will be similar. The fund’s strategy to target a predicted tracking error of approximately 3% compared to the Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS fundamental research is not available for all issuers.

Small Cap Risk: The stocks of small cap companies can be more volatile and their shares can be less liquid than those of larger companies.

MFS Blended Research Small Cap Equity Fund

These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Real Estate Investment Trust Risk: The risks of investing in REITs include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

Performance Information

The bar chart and performance table are not included because the fund has not had a full calendar year of operations.

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager	Since	Title
Matthew W. Krummell	2015	Investment Officer of MFS
James C. Fallon	2015	Investment Officer of MFS
Jonathan W. Sage	2015	Investment Officer of MFS
John E. Stocks	2015	Investment Officer of MFS

Purchase and Sale of Fund Shares

The fund’s initial and subsequent investment minimums generally are as follows:

Class	Initial Minimum	Subsequent Minimum
Class A, Class B, Class C	None – automatic investment plans and certain asset-based fee programs $25 – employer-sponsored retirement plans $250 – Traditional and Roth IRAs $1,000 – other accounts	$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives None – other purchases
Class I, Class R1, Class R2, Class R3, Class R4, Class R6	None	None
Class 529A, Class 529B, Class 529C	None – automatic investment plans $250 – other accounts	None

Taxes

Payments to Broker/Dealers and Other Financial Intermediaries

Investment Objective, Strategies, and Risks

Investment Objective

The fund’s investment objective is to seek capital appreciation. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

MFS normally invests at least 80% of the fund’s net assets in equity securities of issuers with small market capitalizations. MFS generally defines small market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Index over the last 13 months at the time of purchase. As of August 31, 2016, the range of the market capitalizations of the issuers in the Index was between $10.7 million and $4.7 billion. Issuers whose market capitalizations fall outside this definition after purchase continue to be considered to have a small market capitalization for purposes of the 80% policy.

MFS Blended Research Small Cap Equity Fund

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers and their potential in light of their financial condition and market, economic, political, and regulatory conditions to determine a fundamental rating for an issuer. Factors considered may include analysis of an issuer’s earnings, cash flows, competitive position, and management ability. MFS uses quantitative analysis, including quantitative models that systematically evaluate an issuer’s valuation, price and earnings momentum, earnings quality, and other factors, to determine a quantitative rating for an issuer. When MFS quantitative research is available but MFS fundamental research is not available, MFS considers the issuer to have a neutral fundamental rating. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 3% compared to the Index. Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period. A higher tracking error means that the differences between the fund’s returns and the Index’s returns have varied more over time while a lower tracking error means the differences between the fund’s returns and the Index’s returns have varied less over time.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

Principal Investment Types

The principal investment types in which the fund may invest are:

REITs: REITs are pooled investment vehicles that invest primarily in income-producing real estate and/or real estate-related loans or interests. REITs include real estate investment trusts formed under U.S. law as well as similar entities formed under the laws of non-U.S. countries.

Principal Risks

The principal risks of investing in the fund are:

Investment Strategy Risk: There is no assurance that the fund will meet its target predicted tracking error over the long term or for any year or period of years, or that the fund’s predicted tracking error and actual tracking error will be similar. The fund’s strategy to target a predicted tracking error of approximately 3% compared to the Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS fundamental research is not available for all issuers.

Small Cap Risk: The stocks of small cap companies can be more volatile than the stocks of larger companies due to limited product lines, financial and management resources, market and distribution channels. Small cap companies often have shorter operating histories than larger, well-established companies. Their shares can be less liquid than those of larger companies, especially during market declines.

Foreign Risk: Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. Political, social, and economic developments, U.S. and foreign government action such as the imposition of currency or capital controls, economic and trade sanctions or embargoes, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Economies and financial markets are becoming more connected, which increases the likelihood that conditions in one country or region can adversely impact issuers in different countries and regions. Less stringent regulatory, accounting, and disclosure requirements for issuers and markets are more common in certain foreign countries. Enforcing legal rights can be difficult, costly, and slow in certain foreign countries, and can be particularly difficult against foreign governments. Changes in currency exchange rates can affect the U.S. dollar value of foreign currency investments and investments denominated in foreign currencies. Additional risks of foreign investments include trading, settlement, custodial, and other operational risks, and withholding and other taxes. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition,

MFS Blended Research Small Cap Equity Fund

foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, and other conditions than the U.S. market.

Real Estate Investment Trust Risk: The risks of investing in REITs include certain risks associated with the direct ownership of real estate and the real estate industry in general. REITs are affected by general, regional, and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations, and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. Many real estate-related issuers, including REITs, utilize leverage (and some may be highly leveraged), which increases investment risk and could adversely affect the issuer’s operations and market value in periods of rising interest rates. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

REITs could be adversely affected by failure to qualify for the tax-advantaged treatment available to REITs under the Internal Revenue Code of 1986, as amended, or to maintain their exemption from registration under the Investment Company Act of 1940, as amended, and similar risks may also apply to securities of entities similar to REITs formed under the laws of non-U.S. countries.

Other Investment Strategies and Risks

Management of the Fund

Investment Adviser

The management fee set forth in the Investment Advisory Agreement is 0.65% of the fund’s average daily net assets annually up to $1 billion, 0.60% of the fund’s average daily net assets annually in excess of $1 billion and up to $2.5 billion, and 0.575% of the fund’s average daily net assets annually in excess of $2.5 billion.

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the period from September 15, 2015 to May 31, 2016, this management fee reduction amounted to less than 0.01% of the fund’s average daily net assets.

MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.99% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.74% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.74% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 1.24% of the class’ average daily net assets annually for Class R2 shares, 0.70% of the class’ average daily net assets annually for Class R6 shares, 1.04% of the class’ average daily net assets annually for Class 529A shares, and 1.79% of the class’ average daily net asset annually for each of Class 529B and Class 529C shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

A discussion regarding the basis for the Board of Trustees’ approval of the Investment Advisory Agreement is available in the fund’s semiannual report for the period ended November 30, 2015.

Disclosure of Portfolio Holdings . The fund has established a policy with respect to the disclosure of fund portfolio holdings. A description of this policy is provided in the SAI.

MFS Blended Research Small Cap Equity Fund

Information		Approximate Date of Posting To Web Site
Fund’s top 10 holdings as of each month’s end		14 days after month end
Fund’s full holdings as of each month’s end		24 days after month end

Holdings also include short positions, if any.

Portfolio Manager(s)

Portfolio Manager	Primary Role	Five Year History
Matthew W. Krummell	Lead Portfolio Manager	Employed in the investment area of MFS since 2001
James C. Fallon	Portfolio Manager	Employed in the investment area of MFS since 1999
Jonathan W. Sage	Portfolio Manager	Employed in the investment area of MFS since 2000
John E. Stocks	Portfolio Manager	Employed in the investment area of MFS since 2001

Administrator

Distributor

MFS Fund Distributors, Inc. (“MFD”), a wholly owned subsidiary of MFS, is the distributor of shares of the fund.

Shareholder Servicing Agent

Program Manager(s)

Description of Share Classes

The fund offers Class A, Class B, Class C, Class I, Class 529A, Class 529B, Class 529C, Class R1, Class R2, Class R3, Class R4, and Class R6 shares through this prospectus. All classes of the fund have the same investment objective and investments, but each class has its own sales charge and expense structure. Your financial intermediary may also charge you additional fees, commissions, or other charges. You should consult with your financial intermediary to help you determine which class is most appropriate for you.

Class I shares generally are available only to the following eligible investors:

· certain retirement plans established for the benefit of employees and former employees of MFS or its affiliates;

· defined benefit retirement plans, endowments or foundations;

· bank trust departments or law firms acting as trustee or manager for trust accounts;

· investors who purchase shares through asset-based fee programs available through financial intermediaries;

In addition, MFD may accept, in its sole discretion, investments in Class I shares from purchasers not listed above.

MFS Blended Research Small Cap Equity Fund

Class C shareholders may be able to convert their Class C shares not subject to a CDSC to Class I shares of the fund if they satisfy eligibility requirements of Class I shares.

Sales Charges and Waivers or Reductions

Class A and Class 529A Shares. You may purchase Class A and Class 529A shares at the offering price (which includes the applicable initial sales charge).

The amount of the initial sales charge you pay when you buy Class A or Class 529A shares differs depending upon the amount you invest, as follows:

	INITIAL SALES CHARGE AS PERCENTAGE OF:
Amount of Purchase	GROSS PURCHASE AMOUNT (OFFERING PRICE*)		NET AMOUNT INVESTED
Less than $50,000	5.75	%	6.10	%
$50,000 but less than $100,000	4.75	%	4.99	%
$100,000 but less than $250,000	3.75	%	3.90	%
$250,000 but less than $500,000	2.75	%	2.83	%
$500,000 but less than $1,000,000	2.00	%	2.04	%
$1,000,000 or more	None		None

The CDSC is imposed according to the following schedule:

Year of redemption after purchase		1st		2nd		3rd		4th		5th		6th		7th
Contingent deferred sales charge		4	%	4	%	3	%	3	%	2	%	1	%	0	%

Class I Shares. Eligible investors may purchase Class I shares at net asset value without an initial sales charge or a CDSC upon redemption.

MFS Blended Research Small Cap Equity Fund

	INVESTMENTS ELIGIBLE FOR:
Program	WAIVED INITIAL SALES CHARGE	REDUCED INITIAL SALES CHARGE	WAIVED CDSC
Letter of Intent		X
Right of Accumulation		X
Automatic Exchange Plan	X*
Exchange Privilege	X*
Systematic Withdrawal Plan			X**
Distribution Reinvestment	X
Distribution Investment Program	X
Reinstatement Privilege	X
Other Sales Charge Waivers	X		X

* Investments under the Automatic Exchange Plan or certain other exchanges may be subject to a sales charge in certain cases.

** Limited for Class A, Class B, Class C, Class 529B, and Class 529C shares.

Eligible accounts that you may link under an LOI and ROA are:

· Individual accounts;

· Joint accounts;

· Trust accounts of which you, your spouse (or legal equivalent under applicable state law), or child under the age of 21 is the grantor;

· MFS 529 College Savings Plan accounts;

· Certain single-participant retirement plan accounts;

· Certain Individual Retirement Accounts;

· Uniform Gifts/Transfers to Minor Acts accounts; and

· Accounts held in the name of your financial intermediary on your behalf.

Special Note for ROA eligible accounts linked prior to May 1, 2006. Any ROA eligible accounts linked

MFS Blended Research Small Cap Equity Fund

prior to May 1, 2006, will remain linked to the extent the broker/dealer information for such accounts is not modified. In the event you change the broker/dealer for any such account, your accounts will no longer be eligible to be linked under an ROA. In addition, with respect to ROA eligible accounts linked prior to May 1, 2006, you will not be able to link additional accounts to the extent they do not meet the criteria discussed above.

· Systematic Withdrawal Plan. If you have a balance of at least $5,000 in your account in the fund, you may elect to receive (or designate someone else to receive) regular periodic payments (of at least $50 if by check) through an automatic redemption of Class A, Class B, Class C, Class I, Class 529A, Class 529B, or Class 529C shares. For Class A, Class B, Class C, Class 529B, or Class 529C shares, you may incur a CDSC when Class A, Class B, Class C, Class 529B, or Class 529C shares are redeemed under the plan (or plans if more than one plan is established) if greater than 10% of the value of your account is withdrawn under the plan(s) in any one year (determined at the time of your first withdrawal under the plan(s), or January 4, 2016, with respect to Class A shares, January 3, 2007, with respect to Class B or Class 529B shares, or January 2, 2008, with respect to Class C or Class 529C shares, whichever is later). The applicable CDSC will be prorated across all of your payments taken in the one year period.

· Distribution Reinvestment. You may automatically reinvest dividend and capital gain distributions in the same fund without paying an initial sales charge.

Any CDSC paid upon the redemption of Class B shares will not be credited to your account.

Shares acquired through reinvestment of distributions are not subject to a CDSC.

Distribution and Service Fees

The fund has adopted a plan in accordance with Rule 12b-1 under the Investment Company Act of 1940, as amended (the “Distribution Plan”). Under the Distribution Plan, the fund pays distribution and/or service fees to MFD to support the sale and distribution of Class A, Class B, Class C, Class 529A, Class 529B, Class 529C, Class R1, Class R2, and Class R3 shares, and/or shareholder servicing and account maintenance activities. These distribution and/or service fees equal on an annual basis up to the following maximum percentages of average daily net assets of the class:

CLASS	MAXIMUM DISTRIBUTION FEE		MAXIMUM SERVICE FEE		MAXIMUM TOTAL DISTRIBUTION AND SERVICE FEE
Class A	0.00	%	0.25	%	0.25	%
Class B	0.75	%	0.25	%	1.00	%
Class C	0.75	%	0.25	%	1.00	%
Class 529A	0.00	%	0.25	%	0.25	%
Class 529B	0.75	%	0.25	%	1.00	%
Class 529C	0.75	%	0.25	%	1.00	%
Class R1	0.75	%	0.25	%	1.00	%
Class R2	0.25	%	0.25	%	0.50	%
Class R3	0.00	%	0.25	%	0.25	%

The fund has not adopted a Rule 12b-1 plan with respect to its Class I, Class R4, or Class R6 shares.

Financial Intermediary Compensation

MFS Blended Research Small Cap Equity Fund

administrator, insurance company, and any other institution having a selling, administration, or any similar agreement with MFD, MFS, or any of their affiliates.

Financial intermediaries receive various forms of compensation in connection with the sale of shares of a fund and/or the servicing of shareholder accounts. Financial intermediaries may receive such compensation (i) in the form of up-front commissions and ongoing asset-based compensation paid by MFD based on sales charges received and expected to be received by MFD from shareholders and Distribution Plan distribution and service payments received by MFD from the fund, (ii) in the form of 529 administrative services payments and shareholder servicing payments paid by MFD and/or one or more of its affiliates (for purposes of this section only, collectively, “MFD”) based on the receipt of such payments by MFD from the fund, and (iii) in the form of payments paid by MFD from MFD’s own additional resources.

Financial intermediaries may receive up-front commissions of up to the following percentage amounts for sales of the following share classes:

SHARE CLASS	UP FRONT COMMISSION AS A PERCENTAGE OF OFFERING PRICE
Class A or Class 529A	5.75	%
Class B or Class 529B	3.75	%
Class C or Class 529C	1.00	%

How To Purchase, Redeem, and Exchange Shares

How to Purchase Shares

Class A, Class B, and Class C Shares. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

MFS Blended Research Small Cap Equity Fund

Class B share purchases or $999,999 for Class C share purchases, you will not be able to purchase Class B or Class C shares, as applicable. For the purpose of determining your total account value, existing accounts for all share classes held with the MFS funds that are linked under a LOI or ROA will be included.

Class I Shares. You can establish an account through your MFD representative, by having your financial intermediary process your purchase, or by contacting MFSC directly.

529 Share Classes. You can establish an account by having your financial intermediary process your purchase or by contacting MFSC directly.

Additional Purchases

You may purchase additional shares through your financial intermediary or MFSC.

· Additional Purchases Directly Through MFSC.

· Mail. You may purchase additional shares by mailing a check with your investment instructions to MFSC.

· Wire. To purchase additional shares by wire, call MFSC for instructions.

How to Redeem Shares

You may redeem your shares either by having your financial intermediary process your redemption or by contacting MFSC directly.

MFS Blended Research Small Cap Equity Fund

Redeeming Directly Through MFSC.

How to Exchange Shares

An exchange involves the redemption of shares of one fund and the purchase of shares of another fund.

You can exchange your Class A shares and your Class I shares for shares of the MFS U.S. Government Money Market Fund, if available, according to the terms of such fund’s prospectus.

Other Considerations

Disruptive Trading

General Purchase and Exchange Limitation Policy . The MFS funds reserve the right to restrict, reject, or cancel, without any prior notice, any purchase or exchange order, including transactions

MFS Blended Research Small Cap Equity Fund

believed to represent frequent or other disruptive trading activity. In the event that MFSC rejects or cancels an exchange request, neither the redemption nor the purchase side of the exchange will be processed. Each MFS fund reserves the right to delay for one business day the processing of exchange requests in the event that, in MFSC’s judgment, in consultation with MFS, as appropriate, such delay would be in the fund’s best interest, in which case both the redemption and purchase side of the exchange will receive the funds’ net asset values at the conclusion of the delay period.

MFSC reviews trading activity to detect trading activity that may be indicative of frequent trading based on its internal parameters for

MFS Blended Research Small Cap Equity Fund

detecting frequent trading, including reviewing transactions (including exchanges) that exceed a certain dollar amount, transactions involving similar dollar amounts, or transactions that occur close in time to other transactions in the same account or in multiple accounts that are under common ownership or influence. Any or all of these parameters (including those not listed) may change at any time. MFSC does not review the trading activity by other MFS funds that invest in the fund. If MFSC detects suspicious trading activity at the omnibus account level, it will contact the financial intermediary to request underlying shareholder level activity to determine whether there is underlying shareholder level frequent trading. However, the underlying shareholder data received may not reflect information about the ultimate underlying shareholders because there may be multiple layers of omnibus accounts. If frequent trading is identified, MFSC will take appropriate action, such as requesting the financial intermediary to prohibit purchases into the account by the underlying shareholder, requiring purchases by the underlying shareholder to be submitted only by mail, or prohibiting purchases from the financial intermediary.

Other Information

Valuation

In addition, investments may be valued at fair value if MFS determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as a foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, foreign equity securities may often be valued at fair value. MFS generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can

MFS Blended Research Small Cap Equity Fund

be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Distributions

The fund intends to declare and pay any dividends to shareholders at least annually.

Any capital gains are distributed at least annually.

Distribution Options

The following distribution options are generally available:

· Dividend and capital gain distributions automatically reinvested in additional shares (this option will be assigned if no other option is specified) ;

· Dividend distributions in cash; capital gain distributions automatically reinvested in additional shares;

· Dividend and capital gain distributions in cash; or

· Dividend and capital gain distributions automatically reinvested into the same class of shares of another MFS Fund.

Not all options are available for every class or every account.

Dividends and capital gain distributions for Class 529A, Class 529B, Class 529C, Class R1, Class R2, Class R3, Class R4, and Class R6 shares automatically will be reinvested in additional shares of the fund.

Tax Considerations

Any gain resulting from the redemption, sale, or exchange of your shares will generally also be subject to tax.

MFS Blended Research Small Cap Equity Fund

You are urged to consult your own tax adviser for information about the federal, state, and local tax consequences of your investment in the fund’s 529 share classes.

Information about the Summary Prospectus, Prospectus, and SAI

Provision of Financial Reports and Summary Prospectuses

Additional Information on Fees and Expenses and Performance

Fees and Expenses

Performance Information of Similarly-Managed Accounts

The following table presents the past performance of the MFS Blended Research - US Small Cap Equity Composite (the “Composite”), which consists of accounts advised or sub-advised by MFS. Performance was calculated using a methodology which complies with the calculation requirements of the Global Investment Performance Standards ® (GIPS). The table also shows the average annual total return for Russell 2000 ® Index, a broad-based securities market index (“Index”). The Composite is composed of all fee paying accounts under discretionary management by MFS that have investment objectives, policies, and strategies substantially similar to those of the fund. Likewise, the accounts that make up the Composite have the same portfolio management team as the fund. The gross performance data shown for the Composite does not reflect the deduction of investment advisory fees paid by the accounts composing the Composite and certain other expenses which would be applicable to mutual funds. The net performance data may be more relevant to potential investors in the fund in their analysis of the historical experience of MFS in managing portfolios with investment objectives, policies, and strategies substantially similar to those of the fund. The Composite returns and the Index returns are calculated net of withholding taxes on dividends, interest, and capital gains. Net returns for the Composite are a net of the maximum applicable investment management fees charged by MFS for accounts managed in this strategy. The table also includes the performance of the Composite as adjusted for the expenses (on a percentage basis) that are expected to be borne by shareholders of each class of the fund, net of any fee reduction and/or reimbursement, as reflected in the “Annual Fund Operating Expenses” table. Fees and expenses of the fund differ from those used to calculate the net performance of the Composite.

MFS Blended Research Small Cap Equity Fund

Average Annual Total Returns

(for the Periods Ended December 31, 2015)

	1 YEAR		Since 1-1- 2013 1
Composite (net)	(4.18	)%	14.36	%
Adjusted for Class A Expenses with initial Sales charge of 5.75% 2	(10.08	)%	11.68	%
Adjusted for Class B Expenses 2	(5.31	)%	13.06	%
Adjusted for Class B Expenses with CDSC (Declining over seven years from 4% to 0%) 2	(9.31	)%	12.27	%
Adjusted for Class C Expenses 2	(5.31	)%	13.06	%
Adjusted for Class C Expenses with CDSC (1% for 12 months) 2	(6.31	)%	13.06	%
Adjusted for Class I Expenses 2	(4.36	)%	14.18	%
Adjusted for Class R1 Expenses 2	(5.31	)%	13.06	%
Adjusted for Class R2 Expenses 2	(4.84	)%	13.62	%
Adjusted for Class R3 Expenses 2	(4.60	)%	13.90	%
Adjusted for Class R4 Expenses 2	(4.36	)%	14.18	%
Adjusted for Class R6 Expenses 2	(4.32	)%	14.23	%
Adjusted for Class 529A Expenses with initial Sales charge of 5.75% 2	(10.13	)%	11.62	%
Adjusted for Class 529B Expenses 2	(5.36	)%	13.00	%
Adjusted for Class 529B Expenses with CDSC (Declining over seven years from 4% to 0%) 2	(9.36	)%	12.21	%
Adjusted for Class 529C Expenses 2	(5.36	)%	13.00	%
Adjusted for Class 529C Expenses with CDSC (1% for 12 months) 2	(6.36	)%	13.00	%
Composite (gross)	(3.64	)%	15.02	%
Russell 2000 ® Index	(4.41	)%	11.65	%

1 Inception date of the Composite.

The Russell 2000 ® Index is a trademark/service mark of the Frank Russell Company. Russell ® is a trademark of the Frank Russell Company.

MFS Blended Research Small Cap Equity Fund

Financial Highlights

A Financial Highlights table for Class 529A shares, Class 529B shares, and 529C shares are not included because Class 529A shares, Class 529B shares, and 529C shares had not commenced operations as of the fund’s most recent fiscal year end.

	Period ended 5/31 (c)
	2016

Class A
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.39
Less distributions declared to shareholders
From net investment income	$	(0.03	)
Net asset value, end of period (x)	$	10.36
Total return (%) (r)(s)(t)(x)	3.89		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	5.46		(a)
Expenses after expense reductions (f)	0.96		(a)
Net investment income	0.52		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	637

	Period ended 5/31 (c)
	2016

Class B
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment loss (d)	$	(0.02	)
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.33
From net investment income	$	(0.00	)(w)
Net asset value, end of period (x)	$	10.33
Total return (%) (r)(s)(t)(x)	3.34		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	7.17		(a)
Expenses after expense reductions (f)	1.71		(a)
Net investment loss	(0.25		)(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	98

MFS Blended Research Small Cap Equity Fund

	Period ended 5/31 (c)
	2016

Class C
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment loss (d)	$	(0.02	)
Net realized and unrealized gain (loss) on investments and foreign currency	0.36
Total from investment operations	$	0.34
Less distributions declared to shareholders
From net investment income	$	(0.01	)
Net asset value, end of period (x)	$	10.33
Total return (%) (r)(s)(t)(x)	3.38		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	7.03		(a)
Expenses after expense reductions (f)	1.71		(a)
Net investment loss	(0.24		)(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	89

	Period ended 5/31 (c)
	2016

Class I
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.05
Net realized and unrealized gain (loss) on investments and foreign currency	0.36
Total from investment operations	$	0.41
Less distributions declared to shareholders
From net investment income	$	(0.03	)
Net asset value, end of period (x)	$	10.38
Total return (%) (r)(s)(x)	4.14		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	5.39		(a)
Expenses after expense reductions (f)	0.71		(a)
Net investment income	0.73		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	351

MFS Blended Research Small Cap Equity Fund

	Period ended 5/31 (c)
	2016

Class R1
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment loss (d)	$	(0.02	)
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.33
From net investment income	$	(0.00	)(w)
Net asset value, end of period (x)	$	10.33
Total return (%) (r)(s)(x)	3.33		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	7.32		(a)
Expenses after expense reductions (f)	1.71		(a)
Net investment loss	(0.24		)(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	52

	Period ended 5/31 (c)
	2016

Class R2
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.02
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.37
Less distributions declared to shareholders
From net investment income	$	(0.02	)
Net asset value, end of period (x)	$	10.35
Total return (%) (r)(s)(x)	3.68		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.82		(a)
Expenses after expense reductions (f)	1.21		(a)
Net investment income	0.26		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	52

MFS Blended Research Small Cap Equity Fund

	Period ended 5/31 (c)
	2016

Class R3
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.04
Net realized and unrealized gain (loss) on investments and foreign currency	0.34
Total from investment operations	$	0.38
Less distributions declared to shareholders
From net investment income	$	(0.02	)
Net asset value, end of period (x)	$	10.36
Total return (%) (r)(s)(x)	3.86		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.57		(a)
Expenses after expense reductions (f)	0.96		(a)
Net investment income	0.51		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	52

	Period ended 5/31 (c)
	2016

Class R4
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.05
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.40
Less distributions declared to shareholders
From net investment income	$	(0.03	)
Net asset value, end of period (x)	$	10.37
Total return (%) (r)(s)(x)	4.04		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.32		(a)
Expenses after expense reductions (f)	0.71		(a)
Net investment income	0.76		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	52

MFS Blended Research Small Cap Equity Fund

	Period ended 5/31 (c)
	2016

Class R5
Net asset value, beginning of period	$	10.00
Income (loss) from investment operations
Net investment income (d)	$	0.05
Net realized and unrealized gain (loss) on investments and foreign currency	0.35
Total from investment operations	$	0.40
Less distributions declared to shareholders
From net investment income	$	(0.03	)
Net asset value, end of period (x)	$	10.37
Total return (%) (r)(s)(x)	4.04		(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)	6.31		(a)
Expenses after expense reductions (f)	0.70		(a)
Net investment income	0.77		(a)
Portfolio turnover	47		(n)
Net assets at end of period (000 omitted)	$	1,874

(a) Annualized.

(c) For the period from the commencement of the fund’s investment operations, September 15, 2015, through the stated period end.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

MFS Blended Research Small Cap Equity Fund

MFS Blended Research Small Cap Equity Fund

If you want more information about MFS Blended Research Small Cap Equity Fund, the following documents are available free upon request:

You can get free copies of the annual/semiannual reports, the SAI and other information about the fund, including current net asset values per share, and make inquiries about the fund, by contacting:

Internet: mfs.com

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

Telephone: 1-800-225-2606

Information about the fund (including its prospectus, SAI and shareholder reports) can be reviewed and copied at the:

U.S. Securities and Exchange Commission

Public Reference Room

Washington, DC 20549-1502

The fund’s Investment Company Act file number is 811-4492.

HOW TO CONTACT US

Web site	Account service and literature	Mailing address
mfs.com	Shareholders	MFS Service Center, Inc.
	1-800-225-2606	P.O. Box 55824
MFS TALK	Investment professionals	Boston, MA 02205-5824
1-800-637-8255	1-800-343-2829
24 hours a day	Retirement plan services	Overnight mail
	1-800-637-1255	MFS Service Center, Inc.
		c/o Boston Financial Data Services
		30 Dan Road
		Canton, MA 02021-2809

September 28, 2016

PROSPECTUS

MFS ® Blended Research ® Value Equity Fund

The investment objective of the fund is to seek capital appreciation.

CLASS		TICKER SYMBOL
Class A		BRUDX
Class B		BRUEX
Class C		BRUGX
Class I		BRUHX
Class R1		BRUJX
Class R2		BRUKX
Class R3		BRULX
Class R4		BRUMX
Class R6 (Formerly Class R5)		BRUNX

Table of contents

SUMMARY OF KEY INFORMATION	2
INVESTMENT OBJECTIVE, STRATEGIES, AND RISKS	4
MANAGEMENT OF THE FUND	6
DESCRIPTION OF SHARE CLASSES	6
HOW TO PURCHASE, REDEEM, AND EXCHANGE SHARES	10
OTHER INFORMATION	14
FINANCIAL HIGHLIGHTS	17

BRU-PRO-092816

MFS Blended Research Value Equity Fund

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 7 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Share Class

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

5.75

None

Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)

1.00

% #

4.00

1.00

None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Share Class	A		B		C		I		R1		R2		R3		R4		R6
Management Fee	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%	0.40	%
Distribution and/or Service (12b-1) Fees	0.25	%	1.00	%	1.00	%	None		1.00	%	0.50	%	0.25	%	None		None
Other Expenses	5.04	%	5.04	%	5.04	%	5.04	%	5.04	%	5.04	%	5.04	%	5.04	%	5.03	%
Total Annual Fund Operating Expenses	5.69	%	6.44	%	6.44	%	5.44	%	6.44	%	5.94	%	5.69	%	5.44	%	5.43	%
Fee Reductions and/or Expense Reimbursements 1	(4.95	)%	(4.95	)%	(4.95	)%	(4.95	)%	(4.95	)%	(4.95	)%	(4.95	)%	(4.95	)%	(4.98	)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	0.74	%	1.49	%	1.49	%	0.49	%	1.49	%	0.99	%	0.74	%	0.49	%	0.45	%

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

1 Massachusetts Financial Services Company has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.74% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.49% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.49% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 0.99% of the class’ average daily net assets annually for Class R2 shares, and 0.45% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

MFS Blended Research Value Equity Fund

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.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR		3 YEARS		5 YEARS		10 YEARS
Class A Shares	$	646	$	1,757	$	2,852	$	5,525
Class B Shares assuming
redemption at end of period	$	552	$	1,766	$	2,938	$	5,646
no redemption at end of period	$	152	$	1,466	$	2,742	$	5,646
Class C Shares assuming
redemption at end of period	$	252	$	1,466	$	2,742	$	5,776
no redemption at end of period	$	152	$	1,466	$	2,742	$	5,776
Class I Shares	$	50	$	1,182	$	2,304	$	5,067
Class R1 Shares	$	152	$	1,466	$	2,742	$	5,776
Class R2 Shares	$	101	$	1,325	$	2,526	$	5,432
Class R3 Shares	$	76	$	1,254	$	2,416	$	5,252
Class R4 Shares	$	50	$	1,182	$	2,304	$	5,067
Class R6 Shares	$	46	$	1,177	$	2,297	$	5,058

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. For the period from the fund’s commencement of operations on September 15, 2015 to the fund’s fiscal year end of May 31, 2016, the fund’s portfolio turnover rate was 33% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in equity securities.

Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers to determine a fundamental rating for an issuer. MFS uses quantitative analysis to determine a quantitative rating for an issuer. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 2% compared to the Russell 1000 ® Value Index (the “Index”). Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

Principal Risks

The principal risks of investing in the fund are:

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

MFS Blended Research Value Equity Fund

Performance Information

The bar chart and performance table are not included because the fund has not had a full calendar year of operations.

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager	Since	Title
Jonathan W. Sage	2015	Investment Officer of MFS
James C. Fallon	2015	Investment Officer of MFS
Matthew W. Krummell	2015	Investment Officer of MFS
John E. Stocks	2015	Investment Officer of MFS

Purchase and Sale of Fund Shares

The fund’s initial and subsequent investment minimums generally are as follows:

Class

Initial Minimum

Subsequent Minimum

Class A, Class B, Class C

None – automatic investment plans and certain asset-based fee programs

$25 – employer-sponsored retirement plans

$250 – Traditional and Roth IRAs

$1,000 – other accounts

$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives

None – other purchases

Class I, Class R1, Class R2, Class R3, Class R4, Class R6

None

Taxes

Payments to Broker/Dealers and Other Financial Intermediaries

Investment Objective, Strategies, and Risks

Investment Objective

The fund’s investment objective is to seek capital appreciation. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

MFS normally invests at least 80% of the fund’s net assets in equity securities.

MFS focuses on investing the fund’s assets in the stocks of companies that it believes are undervalued compared to their perceived worth (value companies). Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures.

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS uses a bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers and their potential in light of their financial condition and market, economic, political, and regulatory conditions to determine a fundamental rating for an issuer. Factors considered may include analysis of an issuer’s earnings, cash flows, competitive position, and management ability. MFS uses quantitative analysis, including quantitative models that systematically evaluate an issuer’s valuation, price and earnings momentum, earnings quality, and other factors, to determine a quantitative rating for an issuer. When MFS quantitative research is available but MFS fundamental research is not available, MFS considers the issuer to have a neutral fundamental rating. MFS then constructs the portfolio considering the blended rating from combining the fundamental rating and the quantitative rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors, with a goal of constructing a portfolio with a target predicted tracking error of approximately 2% compared to the Index. Tracking error generally measures how the differences between the fund’s monthly returns and the Index’s monthly returns have varied over a specified time period. A higher tracking error means that the differences between the fund’s returns and the Index’s returns have varied more over time while a lower tracking error means the differences between the fund’s returns and the Index’s returns have varied less over time.

For purposes of the fund’s 80% policy, net assets include the amount of any borrowings for investment purposes.

MFS Blended Research Value Equity Fund

Principal Investment Type

The principal investment type in which the fund may invest is:

Equity Securities: Equity securities represent an ownership interest, or the right to acquire an ownership interest, in a company or other issuer. Different types of equity securities provide different voting and dividend rights and priorities in the event of bankruptcy of the issuer. Equity securities include common stocks, preferred stocks, securities convertible into stocks, equity interests in real estate investment trusts (REITs), and depositary receipts for such securities.

Principal Risks

The principal risks of investing in the fund are:

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Foreign Risk: Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. Political, social, and economic developments, U.S. and foreign government action such as the imposition of currency or capital controls, economic and trade sanctions or embargoes, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Economies and financial markets are becoming more connected, which increases the likelihood that conditions in one country or region can adversely impact issuers in different countries and regions. Less stringent regulatory, accounting, and disclosure requirements for issuers and markets are more common in certain foreign countries. Enforcing legal rights can be difficult, costly, and slow in certain foreign countries, and can be particularly difficult against foreign governments. Changes in currency exchange rates can affect the U.S. dollar value of foreign currency investments and investments denominated in foreign currencies. Additional risks of foreign investments include trading, settlement, custodial, and other operational risks, and withholding and other taxes. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, and other conditions than the U.S. market.

Other Investment Strategies and Risks

MFS Blended Research Value Equity Fund

Management of the Fund

Investment Adviser

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the period from September 15, 2015 to May 31, 2016, this management fee reduction amounted to less than 0.01% of the fund’s average daily net assets.

MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund’s investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.74% of the class’ average daily net assets annually for each of Class A and Class R3 shares, 1.49% of the class’ average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.49% of the class’ average daily net assets annually for each of Class I and Class R4 shares, 0.99% of the class’ average daily net assets annually for Class R2 shares, and 0.45% of the class’ average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least September 30, 2017.

A discussion regarding the basis for the Board of Trustees’ approval of the Investment Advisory Agreement is available in the fund’s semiannual report for the period ended November 30, 2015.

Disclosure of Portfolio Holdings . The fund has established a policy with respect to the disclosure of fund portfolio holdings. A description of this policy is provided in the SAI.

Information		Approximate Date of Posting To Web Site
Fund’s top 10 holdings as of each month’s end		14 days after month end
Fund’s full holdings as of each month’s end		24 days after month end

Holdings also include short positions, if any.

Portfolio Manager(s)

Portfolio Manager	Primary Role	Five Year History
Jonathan W. Sage	Lead Portfolio Manager	Employed in the investment area of MFS since 2000
James C. Fallon	Portfolio Manager	Employed in the investment area of MFS since 1999
Matthew W. Krummell	Portfolio Manager	Employed in the investment area of MFS since 2001
John E. Stocks	Portfolio Manager	Employed in the investment area of MFS since 2001