Summary Prospectus by Investment Company (Form 497K)

SUMMARY PROSPECTUS

January 28, 2026

MFS^® Total Return Fund

Before you invest, you may want to review the fund's prospectus, which contains more information about the fund and its risks. You can find the fund's prospectus and other information about the fund, including the fund's reports to shareholders and statement of additional information, online at funds.mfs.com. You can also get this information at no cost by calling 1-800-225-2606 or by sending an e-mail request to [email protected]. The fund's prospectus and statement of additional information, both dated January 28, 2026, as may be amended or supplemented from time to time, are incorporated by reference into this summary prospectus.

CLASS	TICKER SYMBOL
Class A	MSFRX
Class B	MTRBX
Class C	MTRCX
Class I	MTRIX
Class R1	MSFFX
Class R2	MTRRX
Class R3	MSFHX
Class R4	MSFJX
Class R6	MSFKX

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, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below.

You may qualify for sales charge reductions if, with respect to Class A shares, 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 and Reductions" on page 12 and "Appendix A - Waivers and Reductions of Sales Charges" on page A-1 of the fund's prospectus.

Shareholder Fees (fees paid directly from your investment):

Share Class

A

B

C

I

R1

R2

R3

R4

R6

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

5.75%

None

None

None

None

None

None

None

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

None

None

None

None

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		0.35%			0.35%		0.35%		0.35%		0.35%		0.35%		0.35%		0.35%		0.35%
	Distribution and/or Service (12b-1) Fees		0.25%			1.00%		1.00%		None		1.00%		0.50%		0.25%		None		None
	Other Expenses		0.12%			0.12%		0.12%		0.12%		0.12%		0.12%		0.12%		0.12%		0.05%
	Total Annual Fund Operating Expenses		0.72%			1.47%		1.47%		0.47%		1.47%		0.97%		0.72%		0.47%		0.40%

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

MTR-SUM-012826

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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		$644		$792		$953		$1,418
	Class B Shares assuming1
	redemption at end of period		$550		$765		$1,003		$1,554
	no redemption at end of period		$150		$465		$803		$1,554
	Class C Shares assuming1
	redemption at end of period		$250		$465		$803		$1,554
	no redemption at end of period		$150		$465		$803		$1,554
	Class I Shares		$48		$151		$263		$591
	Class R1 Shares		$150		$465		$803		$1,757
	Class R2 Shares		$99		$309		$536		$1,190
	Class R3 Shares		$74		$230		$401		$894
	Class R4 Shares		$48		$151		$263		$591
	Class R6 Shares		$41		$128		$224		$505

1 Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years.

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 41% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund's investment adviser) invests the fund's assets in equity securities and debt instruments. Equity securities include common stocks, depositary receipts, and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer. Debt instruments include corporate debt instruments, U.S. Government securities, securitized instruments (including mortgage-backed securities and other asset-backed securities), and other obligations to repay money borrowed. MFS generally invests approximately 60% of the fund's assets in equity securities and approximately 40% of the fund's assets in debt instruments. These weightings do not reflect the fund's cash balance and can vary over time due to market movements and cash flows.

Of the fund's investments in equity securities, 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 normally invests a portion of the fund's assets in income-producing equity securities.

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

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

MFS may purchase or sell securities for the fund on a when-issued, delayed delivery, or forward commitment basis where payment and delivery take place at a future settlement date, including mortgage-backed securities purchased or sold in the to be announced (TBA) market.

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

MFS normally invests the fund's assets across different industries and sectors, but MFS may invest a significant percentage of the fund's assets in issuers in a single industry or sector.

While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, 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 exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, and swaps.

MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers and instruments. Quantitative screening tools that systematically evaluate issuers and instruments may also be considered.

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:

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. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

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.

Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.

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These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.

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 durations, 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, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

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.

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk: The purchaser in a when-issued, delayed delivery or forward commitment transaction assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued or delivered as anticipated. When-issued, delayed delivery, and forward commitment transactions can involve leverage. TBA transactions may significantly increase the fund's portfolio turnover rate.

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.

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.

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 prices or times that are not advantageous in order to meet redemptions or other cash needs.

Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would.

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 (i) a broad measure of market performance and (ii) the performance of additional indices that the adviser believes more closely reflects the market segments in which the fund invests.

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.

During the period(s) shown in the bar chart, the highest quarterly return was 11.90% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (14.15)% (for the calendar quarter ended March 31, 2020).

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Performance Table.

Average Annual Total Returns
(For the Periods Ended December 31, 2025)

	Share Class		1 YEAR		5 YEARS		10 YEARS
	Returns Before Taxes
	B Shares		6.16%		5.18%		6.84%
	C Shares		9.22%		5.50%		6.84%
	I Shares		11.26%		6.55%		7.75%
	R1 Shares		10.17%		5.50%		6.68%
	R2 Shares		10.75%		6.02%		7.21%
	R3 Shares		11.02%		6.29%		7.48%
	R4 Shares		11.29%		6.56%		7.75%
	R6 Shares		11.40%		6.63%		7.83%
	A Shares		4.60%		5.03%		6.85%
	Returns After Taxes on Distributions
	A Shares		2.26%		3.09%		5.19%
	Returns After Taxes on Distributions and Sale of Fund Shares
	A Shares		3.94%		3.58%		5.11%
	Index Comparisons (Reflects no deduction for fees, expenses, or taxes)
	Standard & Poor's 500 Stock Index		17.88%		14.42%		14.82%
	MFS Total Return Blended Index		13.70%		8.47%		9.78%
	Bloomberg U.S. Aggregate Bond Index		7.30%		(0.36)%		2.01%

As of December 31, 2025, the MFS Total Return Blended Index (the Blended Index) consisted of the following indices and weightings: 60% Standard & Poor's 500 Stock Index and 40% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future.

After-tax returns are calculated using the historical highest individual U.S. 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 (IRAs). 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
Steven Gorham	2002	Investment Officer of MFS
Alexander Mackey	2019	Co-Chief Investment Officer-Global Fixed Income of MFS
Joshua Marston	2008	Investment Officer of MFS
Johnathan Munko	2019	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 (the NYSE) 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, Suite 219341, 801 Pennsylvania Avenue, Kansas City, MO 64105-1307), by mail ([Fund Name], P.O. Box 219341, Kansas City, MO 64121-9341), by telephone (1-800-225-2606), or via the Internet at mfs.com (MFS Access).

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

Purchases of Class B shares are closed to new and existing investors except through reinvestment of dividends and capital gain distributions. Existing investors may continue to exchange their Class B shares for the same share class of another MFS fund.

Purchases of Class R1 and Class R2 shares are closed to new eligible investors. Existing eligible investors can make additional purchases and reinvest distributions in Class R1 and Class R2 shares in any account open. Existing eligible investors may also exchange their Class R1 and Class R2 shares for the same share class of another MFS fund, open new Class R1 and Class R2 share accounts in other MFS funds, or transfer some or all of the shares in their account to another account and such account will be treated as an open account. Subject to the approval of the fund's Board of Trustees, the fund may in the future (i) close purchases of Class R1 and/or Class R2 shares to existing eligible investors; (ii) terminate and liquidate Class R1 and/or Class R2 shares; or (iii) convert Class R1 and/or Class R2 shares to another share class of the fund. Such actions may be undertaken without shareholder approval, but the fund expects to provide shareholders with at least 60 days' notice before taking any such action.

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. However, if your shares are held in a tax-advantaged account, you will generally be taxed only upon withdrawals from the account unless such an account allows for tax-free withdrawals.

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 the fund and/or the servicing of shareholder accounts.

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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 website for more information.

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