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 orderliterature@mfs.com. The fund’s prospectus and statement of additional information, both dated December 27, 2019, as may be amended or supplemented from time to time, are incorporated by reference into this summary prospectus.

CLASS	TICKER SYMBOL
Class A	MSRXX
Class B	MCRXX
Class C	MCCXX
Class I	CRHXX
Class 529A	MACXX
Class 529B	MRBXX
Class 529C	MRCXX
Class R1	CRVXX
Class R2	CRMXX
Class R3	CRJXX
Class R4	CRKXX
Class R6	CRRXX

Beginning on January 1, 2021, as permitted by regulations adopted by the U.S. Securities and Exchange Commission, paper copies of the fund's annual and semiannual shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports. Instead, the complete reports will be made available on the fund's Web site (funds.mfs.com), and you will be notified by mail each time a report is posted and provided with a Web site link to access the report.

If you are already signed up to receive shareholder reports by email, you will not be affected by this change and you need not take any action. You may sign up to receive shareholder reports and other communications from the fund by email by contacting your financial intermediary (such as a broker-dealer or bank) or, if you hold your shares directly with the fund, by calling 1-800-225-2606 or by logging on to MFS Access at mfs.com.

Beginning on January 1, 2019, you may elect to receive all future reports in paper free of charge. Contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. If you invest directly with the fund, you can call 1-800-225-2606 or send an email request to orderliterature@mfs.com to let the fund know that you wish to continue receiving paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held in your account if you invest through your financial intermediary or all funds held with the MFS fund complex if you invest directly.

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek current income consistent with preservation of capital and liquidity.

Fees and Expenses

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

Shareholder Fees (fees paid directly from your investment):

Share Class

A AND 529A

B AND 529B

C AND 529C

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

None

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

None

4.00%

1.00%

None

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MFS U.S. Government Cash Reserve Fund

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	0.40%	0.40%	0.40%	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	0.25%	1.00%	1.00%	1.00%	0.50%	0.25%	None	None
	Other Expenses	0.33%	0.33%	0.33%	0.33%	0.38%	0.38%	0.38%	0.33%	0.33%	0.33%	0.33%	0.26%
	Total Annual Fund Operating Expenses	0.98%	1.73%	1.73%	0.73%	1.03%	1.78%	1.78%	1.73%	1.23%	0.98%	0.73%	0.66%
	Fee Reductions and/or Expense Reimbursements¹	(0.25)%	(1.00)%	(1.00)%	0.00%	(0.25)%	(1.00)%	(1.00)%	(1.00)%	(0.50)%	(0.25)%	0.00%	0.00%
	Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	0.73%	0.73%	0.73%	0.73%	0.78%	0.78%	0.78%	0.73%	0.73%	0.73%	0.73%	0.66%

MFS Fund Distributors, Inc., has agreed in writing to waive the Class A, Class B, Class C, Class 529A, Class 529B, Class 529C, Class R1, Class R2 and Class R3 service fee to 0.00% of the class' average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2020. MFS Fund Distributors, Inc., has agreed in writing to waive the Class B, Class C, Class 529B, Class 529C, Class R1 and Class R2 distribution fee to 0.00% of the class' average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2020.

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	$75	$287	$517	$1,179
Class B Shares assuming
redemption at end of period	$475	$747	$1,045	$1,757
no redemption at end of period	$75	$447	$845	$1,757
Class C Shares assuming
redemption at end of period	$175	$447	$845	$1,958
no redemption at end of period	$75	$447	$845	$1,958
Class I Shares	$75	$233	$406	$906
Class 529A Shares	$80	$303	$544	$1,237
Class 529B Shares assuming
redemption at end of period	$480	$763	$1,071	$1,812
no redemption at end of period	$80	$463	$871	$1,812
Class 529C Shares assuming
redemption at end of period	$180	$463	$871	$2,012
no redemption at end of period	$80	$463	$871	$2,012
Class R1 Shares	$75	$447	$845	$1,958
Class R2 Shares	$75	$341	$628	$1,444
Class R3 Shares	$75	$287	$517	$1,179
Class R4 Shares	$75	$233	$406	$906
Class R6 Shares	$67	$211	$368	$822

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 99.5% of the fund’s total assets in cash, U.S. Government money market instruments, and/or repurchase agreements collateralized by cash or U.S. Government securities. MFS normally invests at least 80% of the fund’s net assets in U.S. Government money market instruments and repurchase agreements collateralized by U.S. Government securities.

In buying and selling investments for the fund, MFS follows U.S. Securities and Exchange Commission rules for money market funds regarding credit quality, diversification, liquidity, and maturity. MFS stresses maintaining a stable $1.00 per share price, liquidity, and income.

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

Principal Risks

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund's sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

The principal risks of investing in the fund are:

Interest Rate Risk: In general, the price of a money market instrument falls when interest rates rise and rises when interest rates

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MFS U.S. Government Cash Reserve Fund

fall. A major or unexpected increase in interest rates could cause the fund's share price to decrease to below $1.00 per share.

Credit and Market Risk: The value of a money market instrument depends on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment. The value of a money market instrument can also decline in response to changes in, or perceptions of, the financial condition of the issuer or borrower, changes in, or perceptions of, specific market, economic, industry, political, regulatory, geopolitical, environmental, and other conditions that affect a particular type of instrument, issuer, or borrower, and changes in, or perceptions of, general market, economic, industry, political, regulatory, geopolitical, environmental, and other conditions.

Redemption Risk: Large or frequent redemptions could cause the fund's share price to decrease to below $1.00 per share.

Issuer Focus Risk: If MFS invests a significant percentage of the fund's assets in a single issuer or small number of issuers, the fund’s performance could be more volatile than the performance of more diversified funds.

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 costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities.

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.

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 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.

Performance information prior to July 1, 2014, reflects time periods when the fund was not considered a U.S. Government money market fund and had different investment policies and strategies. The fund's investment policies and strategies changed effective July 1, 2014. The fund’s past performance 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 total return for the nine-month period ended September 30, 2019, was 1.20%. During the period(s) shown in the bar chart, the highest quarterly return was 0.38% (for the calendar quarter ended December 31, 2018) and the lowest quarterly return was 0.00% (for the calendar quarter ended March 31, 2017).

Performance Table.

Average Annual Total Returns
(For the Periods Ended December 31, 2018)

Share Class	1 YEAR	5 YEARS	10 YEARS
A Shares	1.12%	0.27%	0.13%
B Shares	(2.88)%	(0.13)%	0.13%
C Shares	0.12%	0.26%	0.13%
I Shares	1.12%	0.26%	0.13%
529A Shares	1.07%	0.25%	0.12%
529B Shares	(2.93)%	(0.15)%	0.12%
529C Shares	0.07%	0.25%	0.12%
R1 Shares	1.12%	0.26%	0.13%
R2 Shares	1.12%	0.26%	0.13%
R3 Shares	1.12%	0.26%	0.13%
R4 Shares	1.12%	0.26%	0.13%
R6 Shares	1.14%	0.27%	0.14%

Investment Adviser

MFS serves as the investment adviser for the fund.

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, 430 W 7^th Street, Kansas City, MO 64105-1407), 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:

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MFS U.S. Government Cash Reserve Fund

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

Effective at the close of business on May 29, 2020 (the "Closing Date"), the fund is closed to new and existing investor purchases, subject to the following exceptions. Shareholders of the fund as of the Closing Date may continue to 1) reinvest distributions in the fund; 2) exchange shares from another MFS fund; 3) exercise their one-time Reinstatement Privilege to reinvest in shares of the fund within 90 days of a redemption of fund shares; and 4) transfer some or all of the shares in their account to another account.

In addition, as of the Closing Date, shares of the fund may be purchased by the following investors:

1) Retirement plans other than traditional IRAs, SIMPLE IRAs, Roth IRAs, SEP plans, and SARSEP plans if the fund was offered or officially selected as an investment option by such plan (or any predecessor plan or other plan sponsored by the same employer) as of the Closing Date;

2) Qualified tuition programs established under Section 529 of the Internal Revenue Code of 1986, as amended, if the fund was offered as an investment option by such program on the Closing Date, including the qualified tuition program for which MFD serves as program manager; and

3) Investors approved by the fund, the fund's investment adviser, and the fund's distributor.

The fund reserves the right to modify or limit the above exceptions, or re-open the fund at any time without prior notice.

Financial intermediaries are responsible for enforcing these restrictions with respect to their investors. MFS' ability to monitor financial intermediaries' enforcement of these restrictions is limited by operational systems and the cooperation of financial intermediaries. In addition, with respect to omnibus accounts, MFS' ability to monitor is also limited by a lack of information with respect to the underlying shareholder accounts.

Purchases of Class B and Class 529B 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 or Class 529B shares for the same share class of another MFS fund.

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. The fund expects that substantially all its distributions will consist of investment income taxable as ordinary income. 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.

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