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MFS U.S. Government Cash Reserve Fund

MFS U.S. Government Cash Reserve Fund 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, 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.

Shareholder Fees (fees paid directly from your investment):

Shareholder Fees - MFS U.S. Government Cash Reserve Fund	A	B	C	I	R1	R2	R3	R4	R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	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)	none	4.00%	1.00%	none	none	none	none	none	none

Annual Fund Operating Expenses - MFS U.S. Government Cash Reserve Fund		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		0.26%	0.26%	0.26%	0.26%	0.26%	0.26%	0.26%	0.26%	0.20%
Total Annual Fund Operating Expenses		0.91%	1.66%	1.66%	0.66%	1.66%	1.16%	0.91%	0.66%	0.60%
Fee Reductions and/or Expense Reimbursements	[1]	(0.46%)	(1.21%)	(1.21%)	(0.21%)	(1.21%)	(0.71%)	(0.46%)	(0.21%)	(0.23%)
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements		0.45%	0.45%	0.45%	0.45%	0.45%	0.45%	0.45%	0.45%	0.37%

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:

Expense Example - MFS U.S. Government Cash Reserve Fund - USD ($)		1 YEAR	3 YEARS	5 YEARS	10 YEARS
A		46	244	459	1,077
B	[1]	446	705	988	1,661
C	[1]	146	405	788	1,661
I		46	190	347	803
R1		46	405	788	1,864
R2		46	298	570	1,346
R3		46	244	459	1,077
R4		46	190	347	803
R6		38	169	312	728

Expense Example No Redemption - MFS U.S. Government Cash Reserve Fund - USD ($)		1 YEAR	3 YEARS	5 YEARS	10 YEARS
B	[1]	46	405	788	1,661
C	[1]	46	405	788	1,661

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 fall. A major or unexpected increase in interest rates could cause the fund’s share price to decrease to below $1.00 per share. In addition, a low or negative interest rate environment may prevent the fund from providing a positive yield and could impair the fund’s ability to maintain a stable $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, public health, 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, public health, and other conditions.

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.

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

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.

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.

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, 2022, was 0.43%. During the period(s) shown in the bar chart, the highest quarterly return was 0.42% (for the calendar quarter ended June 30, 2019) and the lowest quarterly return was 0.00% (for the calendar quarter ended September 30, 2021).

Performance Table.

Average Annual Total Returns (For the Periods Ended December 31, 2021)

Average Annual Returns - MFS U.S. Government Cash Reserve Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
A	0.01%	0.59%	0.30%
B	(3.99%)	0.20%	0.30%
C	(0.99%)	0.59%	0.30%
I	0.01%	0.59%	0.30%
R1	0.01%	0.59%	0.30%
R2	0.01%	0.59%	0.30%
R3	0.01%	0.59%	0.30%
R4	0.01%	0.59%	0.30%
R6	0.01%	0.61%	0.31%

[1] Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund’s management fee as part of an agreement pursuant to which MFS has agreed 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. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least December 31, 2023. MFS Fund Distributors, Inc. (MFD), has agreed in writing to waive the Class B, Class C, Class R1, and Class R2 distribution fee to 0.00% of each 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, 2023. MFD has agreed in writing to waive the Class A, Class B, Class C, Class R1, Class R2, and Class R3 service fee to 0.00% of each 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, 2023. 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 0.45% of the class’ average daily net assets annually for each of Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, and Class R4 shares, and 0.37% 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, 2023.

[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.

[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.