Prospectus Supplement

John Hancock Municipal Securities Trust (the Trust)

John Hancock Municipal Opportunities Fund (formerly, John Hancock Tax-Free Bond Fund) (the fund)

Supplement dated March 24, 2022 to the current Summary Prospectus, as may be supplemented (the Summary Prospectus)

At its meeting held on March 22-24, 2022, the Board of Trustees of the Trust approved changes to the fund’s principal investment strategies, effective immediately.

In connection with the changes set forth above, the Summary Prospectus is hereby amended as follows:

The fund’s investment objective is to seek as high a level of interest income exempt from federal income tax as is consistent with preservation of capital. Under normal market conditions, the fund invests at least 80% of its net assets, plus amounts borrowed for investment purposes, in tax-exempt bonds of any maturity. The fund primarily invests in bonds that are investment grade when purchased, but the fund may also invest up to 35% of its net assets in non-investment grade bonds rated BB or lower by S&P Global Ratings (S&P), Fitch Ratings (Fitch), or Moody’s Investors Service, Inc. (Moody’s), or comparable rating by any nationally recognized statistical ratings organization (NRSRO) or unrated equivalents. The fund may invest in other fixed income securities which include bonds, debt securities and other similar instruments. The fund’s investment policies are based on credit ratings at the time of purchase.

The fund may invest in general obligation bonds, however, in general, the manager favors bonds backed by revenue from a specific public project or facility, such as a power plant (revenue bonds), as they tend to offer higher yields than general obligation bonds. The manager also favors bonds that have limitations on early payoff (call protection), which can help minimize the effect of falling interest rates on the fund’s yield. To the extent that the fund invests in bonds that are subject to the alternative minimum tax (AMT), the income paid by the fund may not be entirely tax-free to all investors. Investments in bonds subject to the AMT will not be counted toward the fund’s 80% investment policy.

The fund may buy bonds of any maturity or duration. The fund may invest heavily in bonds from any given state or region, and may have substantial investments in obligations of certain states and their agencies, instrumentalities, and/or political subdivisions. The fund may engage in derivative transactions that include futures contracts on debt securities and debt securities indexes; options on futures, debt securities, and debt indexes; and inverse floating-rate securities, in each case, for the purposes of reducing risk and/or enhancing investment returns. The fund may also use tender option bond transactions to seek to enhance potential gains. The fund will look through to the underlying municipal bonds held by a tender option bond trust for purposes of the fund's 80% policy. The fund may leverage its assets through the use of proceeds received as a result of tender option bond transactions. The fund may contribute up to 15% of its holdings in municipal securities to tender option bond transactions.

Tender option bonds risk. The fund’s participation in tender option bond transactions may increase volatility and/or reduce the fund’s returns. Tender option bond transactions create leverage. Leverage magnifies returns, both positive and negative, and risk by magnifying the volatility of returns. An investment in a tender option bond transaction typically involves greater risk than investing in the underlying municipal fixed rate bonds, including the risk of loss of principal.

You should read this supplement in conjunction with the Summary Prospectus and retain it for your future reference.

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