MFS High Yield Municipal Trust Commences Tender Offer To Purchase Up To 10% Of The Fund's Outstanding Common Shares At A Price Per Share Equal To 98% Of The Fund's Net Asset Value

MFS® High Yield Municipal Trust (the "Fund") (NYSE:CMU) today commenced a cash tender offer for the Fund's common shares. The Fund is offering to purchase up to 10% of the Fund's outstanding common shares (the "Shares") at a price per Share equal to 98% of the Fund's net asset value ("NAV") per Share calculated as of the close of regular trading on the New York Stock Exchange on the date the offer expires. The tender offer will expire at 5:00 P.M., Eastern Standard Time on November 6, 2023, unless extended. The pricing date will also be November 6, 2023, unless the tender offer is extended. If the number of shares tendered exceeds the maximum amount of the offer, the Fund will purchase shares from tendering shareholders on a pro rata basis.

The tender offer is being made on the terms and subject to the conditions set forth in the Fund's tender offer statement on Schedule TO (including an offer to purchase, a related letter of transmittal and other offer documents) that have been filed with the U.S. Securities and Exchange Commission (the "SEC"). All of these documents contain important information about the tender offer. Shareholders of the Fund are urged to read them carefully before any decision is made with respect to the offer. Shareholders of the Fund can obtain a free copy of each of these documents at the SEC's website at www.sec.gov or from the Fund by calling Georgeson LLC, the Fund's information agent for the tender offer, at 1-866-541-3547. This press release is not a recommendation, an offer to purchase, or a solicitation of an offer to sell shares of the Fund and is not a prospectus, circular or representation intended for use in the purchase or sale of Fund shares.