CMU MFS High Yield Municipal Trust

Portfolio Composition - continued

(b)

Cash & Cash Equivalents (Less Liabilities) includes any cash, investments in money market funds, short-term securities, and other assets less liabilities. Liabilities include the value of the aggregate liquidation preference of the remarketable variable rate munifund term preferred shares (RVMTP shares) issued by the fund. Cash & Cash Equivalents (Less Liabilities) is negative due to the aggregate liquidation value of RVMTP shares. Please see the Statement of Assets and Liabilities for additional information related to the fund’s cash position and other assets and liabilities. Please see Note 8 in the Notes to Financial Statements for more information on the RVMTP shares issued by the fund.

(d)

Duration is a measure of how much a bond’s price is likely to fluctuate with general changes in interest rates, e.g., if rates rise 1.00%, a bond with a 5-year duration is likely to lose about 5.00% of its value due to the interest rate move. This calculation is based on net assets applicable to common shares as of November 30, 2021.

(i)

For purposes of this presentation, the components include the value of securities, and reflect the impact of the equivalent exposure of derivative positions, if any. These amounts may be negative from time to time. Equivalent exposure is a calculated amount that translates the derivative position into a reasonable approximation of the amount of the underlying asset that the portfolio would have to hold at a given point in time to have the same price sensitivity that results from the portfolio’s ownership of the derivative contract. When dealing with derivatives, equivalent exposure is a more representative measure of the potential impact of a position on portfolio performance than value. The bond component will include any accrued interest amounts.

(m)

In determining each instrument’s effective maturity for purposes of calculating the fund’s dollar-weighted average effective maturity, MFS uses the instrument’s stated maturity or, if applicable, an earlier date on which MFS believes it is probable that a maturity-shortening device (such as a put, pre-refunding or prepayment) will cause the instrument to be repaid. Such an earlier date can be substantially shorter than the instrument’s stated maturity. This calculation is based on gross assets, which consists of net assets applicable to common shares plus the value of preferred shares, as of November 30, 2021.

Percentages are based on net assets applicable to common shares as of November 30, 2021.

The portfolio is actively managed and current holdings may be different.

3

Management Review

Summary of Results

For the twelve months ended November 30, 2021, common shares of the MFS High Yield Municipal Trust (fund) provided a total return of 7.93%, at net asset value, and a total return of 9.92%, at market value. This compares with a return of 1.97% for the fund’s benchmark, the Bloomberg Municipal Bond Index.

The performance commentary below is based on the net asset value performance of the fund, which reflects the performance of the underlying pool of assets held by the fund. The total return at market value represents the return earned by owners of the shares of the fund, which are traded publicly on the exchange.

Market Environment

Over the past year, the global economy was buffeted by an array of crosscurrents as it adjusted to the ebbs and flows of the pandemic. Among the supportive currents were ample fiscal stimulus, loose monetary policy and the rollout of several highly effective coronavirus vaccines. Negative currents included the rapid spread of several coronavirus variants, widespread global production bottlenecks and a surge in inflation. After experiencing a burst of exceptionally strong economic activity as the global economy began to reopen, growth slowed lately as shortages of raw materials, labor, intermediate goods and even energy in some countries, disrupted supply chains.

Amid rising inflation, markets anticipated a transition from an exceptionally accommodative environment to a more mixed monetary landscape ahead. Indeed, several central banks in emerging markets have already tightened policy and the US Federal Reserve reduced the pace of its asset purchases in November. However, the European Central Bank, the Bank of Japan and the People's Bank of China are expected to maintain accommodative policies. Sovereign bond yields moved modestly higher late in the period amid higher inflation and on expectations of a tighter Fed but slipped lower as the highly-transmissible Omicron variant began to spread at the end of the period.

A harsher Chinese regulatory environment toward industries such as online gaming, food delivery and education increased market volatility as has stress in China's highly leveraged property development sector. Trade relations between the United States and China remained quite strained despite a change in presidential administrations.

Signs of excess investor enthusiasm continued to be seen in pockets of the market such as “meme stocks” popular with users of online message boards, cryptocurrencies and heavy retail participation in the market for short-dated options.

Over the past 12 months, municipal assets continued a rally that had begun in the middle of 2020, supported by the rollout of vaccines, massive amounts of monetary and fiscal support, and a strong economic recovery. Tax receipts avoided worst-case scenarios and, across most states, have fully recovered to 2019 levels this year, bolstering municipal budgets. The economic rebound has benefited revenue-based municipal bonds as well, as demand for education, health care, and travel-related services, among others, returned. Federal funds from fiscal aid packages have gone a long way towards stabilizing liquidity, helping issuers bridge revenue gaps as demand recovers. Improving credit metrics and low distress rates are suggestive of, we believe, further improvement in municipal credit fundamentals. Supply/demand has also been

4

Management Review - continued

supportive for municipal asset prices. Total supply of municipal bond issuance has run at higher levels than the five-year average, however taxable municipal issuance makes up a relatively higher percentage of issuance. Supply of tax-exempt issuance has been lower than the historical average at the same time that investor inflows have been at record levels so far this year. Valuations reflect these positive tailwinds, as spreads have returned to pre-pandemic levels, reducing the attractiveness of taking on excess credit risk. While the recovering economy has benefited credit fundamentals, it has also fueled higher interest rates, a trend we expect to continue due to above-trend levels of growth and inflation. Given tight valuations and our expectations for rates to gradually increase, we believe investors should expect subdued returns for municipal assets in 2022.

Factors Affecting Performance

The fund's asset allocation decisions were a primary driver of relative outperformance versus the Bloomberg Municipal Bond Index. From a credit quality perspective, the fund's out-of-benchmark exposure to both non-rated(r) and “BB” rated bonds, and its greater exposure to “BBB” rated securities, strengthened relative performance. From a sector perspective, a greater exposure to bonds within the health care sector strengthened the fund's relative results.

Security selection further aided relative performance over the reporting period. From a sector perspective, bond selection within the health care sector benefited relative results. From a credit quality perspective, favorable bond selection in “A”, “BB” and “AA” rated issuers supported relative returns.

The fund's positioning along the yield curve(y) was another contributor to relative performance.

The fund employs leverage, which has been created through the issuance of variable rate municipal term preferred shares and remarketable variable rate munifund term preferred shares. To the extent that investments are purchased through the use of leverage, the fund’s net asset value may increase or decrease at a greater rate than a comparable unleveraged fund. During the reporting period, the fund’s use of leverage benefited relative performance.

Conversely, the fund's longer duration(d) stance detracted from relative performance as interest rates generally rose over the reporting period.

Respectfully,

Portfolio Manager(s)

Jason Kosty, Gary Lasman, and Geoffrey Schechter

Note to Shareholders: Effective March 31, 2021, Jason Kosty was added as a Portfolio Manager of the fund.

(d)	Duration is a measure of how much a bond’s price is likely to fluctuate with general changes in interest rates, e.g., if rates rise 1.00%, a bond with a 5-year duration is likely to lose about 5.00% of its value.

(r)

Securities rated “BBB”, “Baa”, or higher are considered investment grade; securities rated “BB”, “Ba”, or below are considered non-investment grade. Ratings are assigned to underlying securities utilizing ratings from Moody's, Fitch, and Standard & Poor's and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping

5

Management Review - continued

the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. If none of the 3 rating agencies above assign a rating, but the security is rated by DBRS Morningstar, then the DBRS Morningstar rating is assigned. If none of the 4 rating agencies listed above rate the security, but the security is rated by the Kroll Bond Rating Agency (KBRA), then the KBRA rating is assigned. Ratings are shown in the S&P and Fitch scale (e.g., AAA). For securities that are not rated by any of the rating agencies, the security is considered Not Rated.

(y)	A yield curve graphically depicts the yields of different maturity bonds of the same credit quality and type; a normal yield curve is upward sloping, with short-term rates lower than long-term rates.

The views expressed in this report are those of the portfolio manager(s) only through the end of the period of the report as stated on the cover and do not necessarily reflect the views of MFS or any other person in the MFS organization. These views are subject to change at any time based on market or other conditions, and MFS disclaims any responsibility to update such views. These views may not be relied upon as investment advice or an indication of trading intent on behalf of any MFS portfolio. References to specific securities are not recommendations of such securities, and may not be representative of any MFS portfolio’s current or future investments.

6

Performance Summary THROUGH 11/30/21

The following chart illustrates the fund’s historical performance in comparison to its benchmark(s). Performance results reflect the percentage change in net asset value and market value, including reinvestment of fund distributions. Benchmarks are unmanaged and may not be invested in directly. Benchmark returns do not reflect commissions or expenses. (See Notes to Performance Summary.)

Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value fluctuate so your shares, when sold, may be worth more or less than the original cost; current performance may be lower or higher than quoted. The performance shown does not reflect the deduction of taxes, if any, that a shareholder would pay on fund distributions or the sale of fund shares.

Growth of a Hypothetical $10,000 Investment

Average Annual Total Returns through 11/30/21

	Inception Date	1-yr	5-yr	10-yr
Market Value (r)	3/19/87	9.92%	6.11%	5.87%
Net Asset Value (r)	3/19/87	7.93%	6.11%	7.37%

Comparative benchmark(s)

Bloomberg Municipal Bond Index (f)	1.97%	4.38%	3.90%

    

(f)	Source: FactSet Research Systems Inc.
(r)	Includes reinvestment of all distributions. Market value references New York Stock Exchange Price.

Benchmark Definition(s)

Bloomberg Municipal Bond Index^(a) – a market capitalization-weighted index that measures the performance of the tax-exempt bond market.

It is not possible to invest directly in an index.

(a)	Source: Bloomberg Index Services Limited. BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg's

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Performance Summary  - continued

licensors own all proprietary rights in the Bloomberg Indices. Bloomberg neither approves or endorses this material, or guarantees the accuracy or completeness of any information herein, or makes any warranty, express or implied, as to the results to be obtained therefrom and, to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.

Notes to Performance Summary

The fund’s shares may trade at a discount or premium to net asset value. When fund shares trade at a premium, buyers pay more than the net asset value underlying fund shares, and shares purchased at a premium would receive less than the amount paid for them in the event of the fund’s concurrent liquidation.

The fund’s monthly distributions may include a return of capital to shareholders to the extent that distributions are in excess of the fund’s net investment income and net capital gains, determined in accordance with federal income tax regulations. Distributions that are treated for federal income tax purposes as a return of capital will reduce each shareholder’s basis in his or her shares and, to the extent the return of capital exceeds such basis, will be treated as gain to the shareholder from a sale of shares. Returns of shareholder capital may have the effect of reducing the fund’s assets and increasing the fund’s expense ratio.

Net asset values and performance results based on net asset value per share do not include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles and may differ from amounts reported in the Statement of Assets and Liabilities or the Financial Highlights.

A portion of the fund’s monthly distributions may be subject to state, federal, and/or alternative minimum tax. Capital gains, if any, are subject to a capital gains tax.

From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

In accordance with Section 23(c) of the Investment Company Act of 1940, the fund hereby gives notice that it may from time to time repurchase shares of the fund in the open market at the option of the Board of Trustees and on such terms as the Trustees shall determine.

8

Investment Objective, Principal Investment Strategies and Principal Risks

Investment Objective

The fund’s investment objective is to seek high current income exempt from federal income tax, but may also consider capital appreciation. The fund’s objective may be changed without shareholder approval.

Principal Investment Strategies

The fund invests, under normal market conditions, at least 80% of its net assets, including assets attributable to preferred shares and borrowings for investment purposes, in tax-exempt bonds and tax-exempt notes. This policy may not be changed without shareholder approval. Tax-exempt bonds and tax-exempt notes are municipal instruments, the interest of 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) 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. Although MFS seeks to invest the funds' assets in municipal instruments whose interest is exempt from federal personal income tax, MFS may also invest in taxable instruments, including derivatives.

MFS may invest up to 100% of the fund’s assets in below investment grade quality debt instruments.

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.

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 in light of the issuers’ financial condition and market, economic, political, and regulatory conditions. Factors considered may include the instrument’s credit quality and terms, any underlying assets and their credit quality, and the issuer’s management ability, capital structure, leverage, and ability to meet its current obligations. MFS may also consider environmental, social, and governance (ESG) factors in its fundamental investment analysis where MFS believes such factors could materially impact the economic value of an issuer or instrument. ESG factors considered may include, but are not limited to, an issuer's governance structure and practices, social issues such as health and safety considerations, and environmental issues such as climate change impact, energy sources, and water and waste management. Quantitative screening tools that systematically evaluate the structure of a debt instrument and its features may also be considered. In structuring the fund, MFS also considers top-down factors, including sector allocations, yield curve positioning, duration, macroeconomic factors, and risk management factors.

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

The fund uses leverage through the issuance of preferred shares and/or the creation of tender option bonds, and then investing the proceeds pursuant to its investment strategies. If approved by the fund’s Board of Trustees, the fund may use leverage by other methods.

MFS may engage in active and frequent trading in pursuing the fund's principal investment strategies.

In response to market, economic, political, or other conditions, MFS may depart from the fund’s principal investment strategies by temporarily investing for defensive purposes.

Principal Investment Types

The principal investment types in which the fund may invest are:

Debt Instruments: Debt instruments represent obligations of corporations, governments, and other entities to repay money borrowed, or other instruments believed to have debt-like characteristics. The issuer or borrower usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the instrument. Debt instruments generally trade in the over-the-counter market and can be less liquid than other types of investments, particularly during adverse market and economic conditions. During certain market conditions, debt instruments in some or many segments of the debt market can trade at a negative interest rate (i.e., the price to purchase the debt instrument is more than the present value of expected interest payments and principal due at the maturity of the instrument). Some debt instruments, such as zero coupon bonds or payment-in-kind bonds, do not pay current interest. Other debt instruments, such as certain mortgage-backed securities and other securitized instruments, make periodic payments of interest and/or principal. Some debt instruments are partially or fully secured by collateral supporting the payment of interest and principal.

Municipal Instruments: Municipal instruments are issued by or for states, territories, or possessions of the United States or by their political subdivisions, agencies, authorities, or other government entities, to raise money for a variety of public and private purposes, including general financing for state and local governments, or financing for a specific project or public facility. Municipal instruments include general obligation bonds of municipalities, state or local governments, project or revenue-specific bonds, municipal lease obligations, and prerefunded or escrowed bonds. Municipal instruments may be fully or partially supported by the state or local governments, by the credit of a private issuer, by the current or anticipated revenues from a specific project or assets, by the issuer’s pledge to make annual appropriations for lease payments, or by domestic or foreign entities providing credit support, such as insurance, letters of credit, or guarantees. Many municipal instruments are supported by insurance, which typically guarantees the timely payment of all principal and interest due on the underlying municipal instrument.

Tender Option Bonds: Tender option bonds are created when municipal instruments are transferred to a special purpose trust which issues two classes of certificates. The first class, commonly called floating rate certificates, pays an interest rate that is typically reset weekly based on a specified index. Each holder of a floating rate certificate has the option at specified times, and/or may be required under specified circumstances, to tender its certificate to the issuer or a specified third party acting as

10

Investment Objective, Principal Investment Strategies and Principal Risks - continued

agent for the issuer for purchase at the stated amount of the certificate plus accrued interest. The second class, commonly called inverse floaters, pays an interest rate based on the difference between the interest rate earned on the underlying municipal instruments and the interest rate paid on the floating rate certificates after expenses.

Derivatives: Derivatives are financial contracts whose value is based on the value of one or more underlying indicators or the difference between underlying indicators. Underlying indicators may include a security or other financial instrument, asset, interest rate, credit rating, commodity, volatility measure, or index. Derivatives often involve a counterparty to the transaction. Derivatives include futures, forward contracts, options, inverse floating rate instruments, swaps, and certain complex structured securities.

Principal Risks

The yield and share price of the fund will change daily based on changes in interest rates and market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. 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 significance of any specific risk to an investment in the fund will vary over time depending on the composition of the fund's portfolio, market conditions, and other factors. You should read all of the risk information below carefully, because any one or more of these risks may result in losses to the fund.

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, MFS or the fund's other service providers may experience disruptions or operating errors that could negatively impact the fund.

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 debt markets generally. Certain changes or events, such as political, social, or economic developments, including increasing and negative interest rates or the U.S. government's inability at times to agree on a long-term budget and deficit reduction plan (which has in the past resulted and may in the future result in a government shutdown); market closures and/or trading halts; government or regulatory actions, including the imposition of tariffs or other protectionist actions and changes in fiscal, monetary, or tax policies; natural disasters; outbreaks of pandemic and epidemic diseases; terrorist attacks; war; and other geopolitical changes or 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 a segment of a debt market.

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

Interest Rate Risk: The price of a debt instrument typically changes in response to interest rate changes. Interest rates can change in response to the supply and demand for credit, government and/or central bank monetary policy and action, inflation rates, general economic and market conditions, and other factors. In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. The current period of historically low interest rates may heighten the risks associated with rising interest rates because there may be a greater likelihood of interest rates increasing and interest rates may increase rapidly. Interest rate risk is generally greater for fixed-rate instruments than floating-rate instruments and for instruments with longer maturities, or that do not pay current interest. In addition, short-term and long-term interest rates do not necessarily move in the same direction or by the same amount. An instrument’s reaction to interest rate changes depends on the timing of its interest and principal payments and the current interest rate for each of those time periods. The price of an instrument trading at a negative interest rate responds to interest rate changes like other debt instruments; however, an instrument purchased at a negative interest rate is expected to produce a negative return if held to maturity. To the extent the fund invests in fixed-rate instruments, fluctuations in the market price of such investments may not affect interest income derived from those instruments, but may nonetheless affect the fund's share price, especially if the instrument has a longer maturity.

Credit Risk: The price of a debt instrument depends, in part, on the issuer's or borrower's credit quality or ability to pay principal and interest when due. The price of a debt instrument is likely to fall if an issuer or borrower defaults on its obligation to pay principal or interest, if the instrument's credit rating is downgraded by a credit rating agency, or based on other changes in, or perceptions of, the financial condition of the issuer or borrower. For certain types of instruments, including derivatives, the price of the instrument depends in part on the credit quality of the counterparty to the transaction. For other types of debt instruments, including securitized instruments and some municipal instruments, the price of the debt instrument also depends on the credit quality and adequacy of the underlying assets or collateral as well as whether there is a security interest in the underlying assets or collateral. Enforcing rights, if any, against the underlying assets or collateral may be difficult.

Below investment grade quality debt instruments can involve a substantially greater risk of default or can already be in default, and their values can decline significantly over short periods of time. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics with respect to capacity to pay interest and principal. 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. The market for below investment grade quality debt instruments can be less liquid, especially during periods of recession or general market decline.

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

12

Investment Objective, Principal Investment Strategies and Principal Risks - continued

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.

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, market and economic conditions and developments, issuer, industry-specific and other conditions, including as the result of events that cannot be reasonably anticipated or controlled such as social conflict or unrest, labor disruption and natural disasters. Municipal instruments can be less liquid than other types of investments and there may be less publicly available information about the issuers of municipal instruments compared to other issuers. If the Internal Revenue Service or a state taxing authority determines that an issuer of a municipal instrument has not complied with applicable tax requirements, interest from the instrument could become taxable (including retroactively) and the instrument could decline significantly in price. Because many municipal instruments are issued to finance similar projects, especially those relating to education, health care, housing, utilities, and water and sewer, conditions in these industries can significantly affect the fund and the overall municipal market. In addition, changes in the financial condition of an individual municipal insurer can affect 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 may adversely impact the value of its bonds, which could negatively impact the performance of the fund. Factors contributing to the economic stress on municipal issuers may include an increase in expenses associated with combatting the COVID-19 pandemic and a decrease in revenues supporting the issuer's bonds due to factors such as lower sales tax revenue as a result of decreased consumer spending, lower income tax revenue due to higher unemployment, and a decrease in the value of collateral backing revenue bonds due to closures and/or curtailment of services and/or changes in consumer behavior. In light of the uncertainty surrounding the magnitude, duration, reach, costs and effects of the COVID-19 pandemic, as well as actions that have been or could be taken by governmental authorities or other third parties, it is difficult to predict the level of financial stress and duration of such stress municipal issuers may experience.

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. These conditions include constitutional or statutory limits on an issuer's ability to raise revenues or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes in the credit quality of municipal issuers in such states, territories, and possessions. 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

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

than the performance of more geographically-diversified funds. A prolonged increase in unemployment or a significant decline in the local and/or national economies, such as the increase in unemployment and economic downturn caused by the COVID-19 pandemic and the costs associated with combatting this pandemic, could result in decreased tax revenues.

Prepayment/Extension Risk: Many types of debt instruments, including mortgage-backed securities, securitized instruments, certain corporate bonds, and municipal housing bonds, and certain derivatives, are subject to the risk of prepayment and/or extension. Prepayment occurs when unscheduled payments of principal are made or the instrument is called or redeemed prior to an instrument’s maturity. When interest rates decline, the instrument is called, or for other reasons, these debt instruments may be repaid more quickly than expected. As a result, the holder of the debt instrument may not be able to reinvest the proceeds at the same interest rate or on the same terms, reducing the potential for gain. When interest rates increase or for other reasons, these debt instruments may be repaid more slowly than expected, increasing the potential for loss. In addition, prepayment rates are difficult to predict and the potential impact of prepayment on the price of a debt instrument depends on the terms of the instrument.

Leveraging Risk: If the fund utilizes investment leverage, there can be no assurance that such a leveraging strategy will be successful during any period in which it is employed. The use of leverage is a speculative investment technique that results in greater volatility in the fund’s net asset value. To the extent that investments are purchased with the proceeds from the borrowings from a bank, the issuance of preferred shares, or the creation of tender option bonds, the fund’s net asset value will increase or decrease at a greater rate than a comparable unleveraged fund. If the investment income or gains earned from the investments purchased with the proceeds from the borrowings from a bank, the issuance of preferred shares, or the creation of tender option bonds, fails to cover the expenses of leveraging, the fund’s net asset value is likely to decrease more quickly than if the fund weren’t leveraged. In addition, the fund’s distributions could be reduced. The fund is currently required under the Investment Company Act of 1940 (the “1940 Act”) to maintain asset coverage of 200% on outstanding preferred shares and 300% on outstanding indebtedness. The fund may be required to sell a portion of its investments at a time when it may be disadvantageous to do so in order to redeem preferred shares or to reduce outstanding indebtedness to comply with asset coverage or other restrictions including those imposed by the 1940 Act and the rating agencies that rate the preferred shares. The expenses of leveraging are paid by the holders of common shares. Borrowings from a bank or preferred shares may have a stated maturity. If this leverage is not extended prior to maturity or replaced with the same or a different form of leverage, distributions to common shareholders may be decreased.

Certain transactions and investment strategies can result in leverage. Because movements in a fund’s share price generally correlate over time with the fund’s net asset value, the market price of a leveraged fund will also tend to be more volatile than that of a comparable unleveraged fund. The costs of an offering of preferred shares and/or borrowing program would be borne by shareholders.

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

Under the terms of any loan agreement or of a purchase agreement between the fund and the investor in the preferred shares, as the case may be, the fund may be required to, among other things, limit its ability to pay distributions in certain circumstances, incur additional debts, engage in certain transactions, and pledge some or all of its assets. Such agreements could limit the fund’s ability to pursue its investment strategies. The terms of any loan agreement or purchase agreement could be more or less restrictive than those described.

Under guidelines generally required by a rating agency providing a rating for any preferred shares, the fund may be required to, among other things, maintain certain asset coverage requirements, restrict certain investments and practices, and adopt certain redemption requirements relating to preferred shares. Such guidelines or the terms of a purchase agreement between a fund and the investor in the preferred shares could limit the fund’s ability to pursue its investment strategies. The guidelines imposed with respect to preferred shares by a rating agency or an investor in the preferred shares could be more or less restrictive than those described.

In addition, the management fee paid to the Adviser is calculated based on net assets, including assets applicable to preferred shares, so the fee will be higher when leverage through the issuance of preferred shares is utilized, which may create an incentive for the Adviser to use leverage through the issuance of preferred shares.

Tender Option Bond Risk: The underlying municipal instruments held by the special purpose trust are sold or distributed in-kind by the trustee if specified events occur, such as a downgrade in the rating of the underlying municipal instruments, a specified decline in the value of the underlying municipal instruments, a failed remarketing of the floating rate certificates, the bankruptcy of the issuer of the underlying municipal instruments and, if the municipal instruments are insured, of both the issuer and the insurer, and the failure of the liquidity provider to pay in accordance with the trust agreement. In the event the trustee sells or distributes in-kind the underlying municipal instruments to pay amounts owed to the floating rate certificate holders, with the remaining amount paid to the inverse floater holders, the fund’s leverage will be reduced.

Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to, and potentially greater than, the risks of the underlying indicator(s). Gains or losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. Derivatives can involve leverage. Derivatives can be complex instruments and can involve analysis and processing that differs from that required for other investment types used by the fund. If the value of a derivative does not change as expected relative to the value of the market or other indicator to which the derivative is intended to provide exposure, the derivative may not have the effect intended. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments.

Anti-Takeover Provisions Risk: The fund’s declaration of trust includes provisions that could limit the ability of other persons or entities to acquire control of the fund, to convert the fund to an open-end fund, or to change the composition of the fund’s Board of Trustees. These provisions could reduce the opportunities for shareholders to sell their Common shares at a premium over the then-current market price.

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

Market Discount/Premium Risk: The market price of Common shares of the fund will be based on factors such as the supply and demand for Common shares in the market and general market, economic, industry, political or regulatory conditions. Whether shareholders will realize gains or losses upon the sale of Common shares of the fund will depend on the market price of Common shares at the time of the sale, not on the fund’s net asset value. The market price may be lower or higher than the fund’s net asset value. Shares of closed-end funds frequently trade at a discount to their net asset value.

Counterparty and Third Party Risk: Transactions involving a counterparty other than the issuer of the instrument, including clearing organizations, or a third party responsible for servicing the instrument or effecting the transaction, 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. If a counterparty or third party fails to meet its contractual obligations, goes bankrupt, or otherwise experiences a business interruption, the fund could miss investment opportunities, lose value on its investments, or otherwise hold investments it would prefer to sell, resulting in losses for the fund.

Liquidity Risk: Certain investments and types of investments are subject to restrictions on resale, may trade in the over-the-counter market, or may not have an active trading market due to adverse market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, including investors trying to sell large quantities of a particular investment or type of investment, or lack of market makers or other buyers for a particular investment or type of investment. At times, all or a significant portion of a market may not have an active trading market. Without an active trading market, it may be difficult to value, and it may not be possible to sell, these investments and the fund could miss other investment opportunities and hold investments it would prefer to sell, resulting in losses for the fund. In addition, 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, which could result in dilution of remaining investors' interests in the fund. The prices of illiquid securities may be more volatile than more liquid investments.

Defensive Investing Risk: When MFS invests defensively, different factors could affect the fund’s performance and the fund may not achieve its investment objective. In addition, the defensive strategy may not work as intended.

Frequent Trading Risk: Frequent trading increases transaction costs, which may reduce the Fund's return. Frequent trading can also result in the realization of a higher percentage of short-term capital gains and a lower percentage of long-term capital gains as compared to a fund that trades less frequently. Because short-term capital gains are distributed as ordinary income, this would generally increase your tax liability unless you hold your shares through a tax-advantaged or tax-exempt vehicle.

Investment Restrictions

The Fund has adopted the following policies which cannot be changed without the approval of the holders of a majority of its shares as defined currently in the 1940 Act to be the lesser of (i) 67% or more of the voting securities present at a meeting at which holders of voting securities representing more than 50% of the outstanding voting securities are present or represented by proxy, or (ii) more than 50% of the

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Investment Objective, Principal Investment Strategies and Principal Risks - continued

outstanding voting securities (“Majority Shareholder Vote”). Except for fundamental investment restriction (1), these investment restrictions are adhered to at the time of purchase or utilization of assets; a subsequent change in circumstances will not be considered to result in a violation of policy.

The Fund may not:

(1)	borrow money except to the extent not prohibited by the 1940 Act and exemptive orders granted under such Act.

(2)

underwrite securities issued by other persons, except that all or any portion of the assets of the Fund may be invested in one or more investment companies, to the extent not prohibited by the 1940 Act and exemptive orders granted under such Act, and except insofar as the Fund may technically be deemed an underwriter under the Securities Act of 1933, as amended, in selling a portfolio security.

(3)

issue any senior securities except to the extent not prohibited by the 1940 Act and exemptive orders granted under such Act. For purposes of this restriction, collateral arrangements with respect to any type of swap, option, Forward Contracts and Futures Contracts and collateral arrangements with respect to initial and variation margin are not deemed to be the issuance of a senior security.

(4)	make loans except to the extent not prohibited by the 1940 Act and exemptive orders granted under such Act.

(5)

purchase or sell real estate (excluding securities secured by real estate or interests therein and securities of companies, such as real estate investment trusts, which deal in real estate or interests therein), interests in oil, gas or mineral leases, commodities or commodity contacts (excluding currencies and any type of option, Futures Contracts and Forward Contracts or other derivative instruments whose value is related to commodities or other commodity contracts) in the ordinary course of its business. The Fund reserves the freedom of action to hold and to sell real estate, mineral leases, commodities or commodity contracts (including currencies and any type of option, Futures Contracts and Forward Contracts) acquired as a result of the ownership of securities.

(6)	purchase any securities of an issuer in a particular industry if as a result 25% or more of its total assets (taken at market value at the time of purchase) would be invested in securities of issuers whose principal business activities are in the same industry.

For purposes of fundamental investment restriction (6), investments in securities issued or guaranteed by the U.S. Government or its agencies or instrumentalities and tax-exempt obligations issued or guaranteed by a U.S. territory or possession, a state or local government, or a political subdivision of any of the foregoing, are not considered an investment in any particular industry.

For purposes of fundamental investment restriction (6), investments in other investment companies are not considered an investment in any particular industry and portfolio securities held by an underlying fund in which the Fund may invest are not considered to be securities purchased by the Fund.

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