Summary Prospectus by Investment Company (Form 497K)

SUMMARY PROSPECTUS

December 29, 2025 (As Amended April 20, 2026)

MFS^® Blended Research^® Emerging Markets Equity 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 December 29, 2025, as may be amended or supplemented from time to time, are incorporated by reference into this summary prospectus.

CLASS	TICKER SYMBOL
Class A	BRKAX
Class B	BRKBX
Class C	BRKCX
Class I	BRKIX
Class R1	BRKRX
Class R2	BRKSX
Class R3	BRKTX
Class R4	BRKUX
Class R6	BRKVX

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, 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. Expenses for Class R1 shares have been adjusted to reflect the full impact of the distribution fee. Expenses have been adjusted to reflect current fee arrangements.

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		0.45%			0.45%		0.45%		0.45%		0.45%		0.45%		0.45%		0.45%		0.45%
	Distribution and/or Service (12b-1) Fees		0.25%			1.00%		1.00%		None		1.00%		0.50%		0.25%		None		None
	Other Expenses		0.57%			0.57%		0.57%		0.57%		0.57%		0.57%		0.57%		0.57%		0.48%
	Total Annual Fund Operating Expenses		1.27%			2.02%		2.02%		1.02%		2.02%		1.52%		1.27%		1.02%		0.93%
	Fee Reductions and/or Expense Reimbursements1		(0.42)%			(0.42)%		(0.42)%		(0.42)%		(0.42)%		(0.42)%		(0.42)%		(0.42)%		(0.39)%
	Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements		0.85%			1.60%		1.60%		0.60%		1.60%		1.10%		0.85%		0.60%		0.54%

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

1 Effective March 1, 2026, MFS has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, certain tax reclaim recovery expenses (including contingency fees and closing agreement expenses), 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 0.85% of the class' average daily net assets annually for each of Class A and Class R3 shares, 1.60% of the class' average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.60% of the class' average daily net assets annually for each of Class I and Class R4 shares, 1.10% of the class' average daily net assets annually for Class R2 shares, and 0.54% 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 December 31, 2027.

BRK-SUM-042026

Page 1 of 4

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		$657		$881		$1,160		$1,955
	Class B Shares assuming1
	redemption at end of period		$563		$857		$1,215		$2,090
	no redemption at end of period		$163		$557		$1,015		$2,090
	Class C Shares assuming1
	redemption at end of period		$263		$557		$1,015		$2,090
	no redemption at end of period		$163		$557		$1,015		$2,090
	Class I Shares		$61		$246		$486		$1,176
	Class R1 Shares		$163		$557		$1,015		$2,285
	Class R2 Shares		$112		$403		$754		$1,745
	Class R3 Shares		$87		$325		$621		$1,464
	Class R4 Shares		$61		$246		$486		$1,176
	Class R6 Shares		$55		$223		$443		$1,075

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 57% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund's investment adviser) seeks to achieve the fund's objective by actively identifying potential investments in issuers economically tied to emerging market countries based on fundamental and quantitative analysis and then constructing a portfolio from these potential investments while managing various risk factors (e.g., issuer, industry, and sector weightings, market capitalization, and volatility) compared to the MSCI Emerging Markets Index.

MFS 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 markets are countries determined to have emerging market economies based on factors that demonstrate the country's financial and capital markets are in the development phase, including whether a particular country has a low- to middle-income economy according to the International Bank for Reconstruction and Development (the World Bank), the country's designation by the International Monetary Fund as an emerging market, or the country's inclusion in an emerging market index. Emerging market countries include countries located in Latin America, Asia, Africa, the Middle East, and developing countries of Europe, primarily Eastern Europe. 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.

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

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

MFS uses an active 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 combines the fundamental rating with the quantitative rating to create a blended rating for an issuer. When the fundamental rating is not available, MFS treats the issuer as having a neutral fundamental rating.

MFS constructs the portfolio using a portfolio optimization process that considers the blended rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors. The portfolio managers have the discretion to adjust the inputs and parameters used in the optimization process and the fund's portfolio holdings based on factors such as the desired portfolio characteristics and the portfolio managers' qualitative assessment of the optimization results. MFS' goal is to construct an actively managed portfolio with a target predicted tracking error of approximately 2% compared to the MSCI Emerging Markets Index. Tracking error generally measures how the differences between the fund's returns and the MSCI Emerging Markets Index's returns have varied over a period of time.

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

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, 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. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures).

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

Page 2 of 4

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.

Investment Strategy Risk: There is no assurance that the fund's predicted tracking error will equal its target predicted tracking error at any point in time or consistently for any period of time, 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 MSCI Emerging Markets 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.

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 emerging markets 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.

Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, 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, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies.

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.

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 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 nine-month period ended September 30, 2025, was 26.96%. During the period(s) shown in the bar chart, the highest quarterly return was 17.30% (for the calendar quarter ended December 31, 2020) and the lowest quarterly return was (25.44)% (for the calendar quarter ended March 31, 2020).

Page 3 of 4

Performance Table.

Average Annual Total Returns
(For the Periods Ended December 31, 2024)

	Share Class		1 YEAR		5 YEARS		LIFE (INCEPTION 9-15-2015)
	Returns Before Taxes
	B Shares		9.01%		1.56%		5.64%
	C Shares		12.03%		1.93%		5.64%
	I Shares		14.08%		2.96%		6.58%
	R1 Shares		13.83%		2.53%		5.85%
	R2 Shares		13.55%		2.44%		6.05%
	R3 Shares		13.81%		2.69%		6.31%
	R4 Shares		14.08%		2.96%		6.58%
	R6 Shares		14.13%		3.04%		6.67%
	A Shares		7.35%		1.51%		5.65%
	Returns After Taxes on Distributions
	A Shares		6.93%		1.11%		5.08%
	Returns After Taxes on Distributions and Sale of Fund Shares
	A Shares		4.90%		1.30%		4.53%
	Index Comparison (Reflects no deduction for fees, expenses, or taxes)
	MSCI Emerging Markets Index (net div)		7.50%		1.70%		5.60%

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
Jed Stocks	2015	Investment Officer of MFS
Nathan Bryant	January 2026	Investment Officer of MFS
Matt Krummell	2015	Investment Officer of MFS
Jonathan Sage	2015	Investment Officer of MFS
Jenney Zhang	January 2026	Investment Officer of MFS

Matt Krummell has announced his intention to retire effective April 7, 2027, and he will no longer be a portfolio manager of the fund as of that date.

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. 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.

Page 4 of 4