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MFS Municipal Intermediate Fund

MFS Municipal Intermediate Fund Summary of Key Information

Investment Objective

The fund’s investment objective is to seek total return with an emphasis on income exempt from federal income tax, but also considering 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 and hold shares of the fund, which are not reflected below.

The annual fund operating expenses are based on estimated “Other Expenses” for the current fiscal year expressed as a percentage of each class’ estimated average net assets during the period.

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 $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 and Reductions” on page 9 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)

Shareholder Fees - MFS Municipal Intermediate Fund	Class A		Class C	Class I	Class R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	4.25%		none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	1.00%	[1]	1.00%	none	none

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

Annual Fund Operating Expenses - MFS Municipal Intermediate Fund		Class A	Class C	Class I	Class R6
Management Fee		0.35%	0.35%	0.35%	0.35%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	none	none
Other Expenses		0.83%	0.83%	0.83%	0.76%
Total Annual Fund Operating Expenses		1.43%	2.18%	1.18%	1.11%
Fee Reductions and/or Expense Reimbursements	[1]	(0.73%)	(0.73%)	(0.73%)	(0.73%)
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements		0.70%	1.45%	0.45%	0.38%

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 Municipal Intermediate Fund - USD ($)	1 YEAR	3 YEARS
Class A	493	774
Class C	248	597
Class I	46	287
Class R6	39	265

Expense Example No Redemption	1 YEAR	3 YEARS
MFS Municipal Intermediate Fund | Class C | USD ($)	148	597

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. The portfolio turnover rate for the fund as of March 31, 2021, the fiscal year end of the fund, is not available because the fund had not commenced operations as of that date.

Principal Investment Strategies

The fund invests, under normal market conditions, at least 80% of its net assets in municipal instruments, the interest on which is exempt from federal income tax. Interest from the fund’s investments may be subject to the federal alternative minimum tax. 

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets primarily in municipal instruments.

MFS primarily invests the fund’s assets in investment grade quality debt instruments, but may also invest in below investment grade quality debt instruments.

The fund’s dollar-weighted average effective maturity will normally range between three and ten years.

MFS may invest 25% or more of the fund’s total assets in municipal instruments that finance similar projects, such as those relating to education, healthcare, housing, utilities, water, or sewers.

MFS may invest a significant percentage of the fund’s assets in issuers in a single state, territory, or possession, or a small number of states, territories, or possessions.

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, inverse floating rate instruments, 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 instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors.

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 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.

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

The credit quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal instrument, how essential any services supported by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations necessary to support the municipal instrument. In addition, the price of a municipal instrument also depends on its credit quality and ability to meet the credit support obligations of any insurer or other entity providing credit support to a municipal instrument.

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.

Municipal Risk: The price of a municipal instrument can be volatile and significantly affected by adverse tax changes or court

rulings, legislative or political changes, changes in specific or general market and economic conditions and developments, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain industries can significantly affect the fund and the overall municipal market.  Municipal instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could affect the market values and marketability of many or all municipal obligations of issuers in a state, U.S. territory, or possession. For example, the novel coronavirus (COVID-19) pandemic has significantly stressed the financial resources of many municipal issuers, which may impair a municipal issuer’s ability to meet its financial obligations when due and could adversely impact the value of its bonds, which could negatively impact the performance of the fund.

Focus Risk: The fund’s performance will be closely tied to the issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions in the states, territories, and possessions of the United States in which the fund’s assets are invested.  If MFS invests a significant percentage of the fund’s assets in a single state, territory, or possession, or a small number of states, territories, or possessions, these conditions will have a significant impact on the fund’s performance and the fund’s performance may be more volatile than the performance of more geographically-diversified funds.

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.

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 are not included because the fund has not had a full calendar year of operations.  Once the fund has commenced operations, updated performance information will be available online at mfs.com or by calling 1-800-225-2606.  The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future.

[1] 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 0.70% of the class’ average daily net assets annually for Class A shares, 1.45% of the class’ average daily net assets annually for Class C shares, 0.45% of the class’ average daily net assets annually for Class I shares, and 0.38% 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 July 31, 2022.