X0202 SCHEDULE 13D/A 0001504304-23-000019 0001504304 XXXXXXXX LIVE 11 Common Stock 04/23/2026 false 0000809844 59318E102 MFS High Yield Municipal Trust

111 Huntington Avenue Boston MA 02199

Phillip Goldstein 914 747-5262 250 Pehle Ave. Suite 708 Saddle Brook NJ 07663 0001504304 N Bulldog Investors, LLP WC N DE 120488.00 2693673.00 120488.00 2693673.00 2814161.00 N 11.04 IA Y Phillip Goldstein WC N X1 120488.00 3076658.00 120488.00 3076658.00 3197146.00 N 12.54 IN Y Andrew Dakos WC N X1 0.00 2699273.00 0.00 2699273.00 2699273.00 N 10.59 IN Common Stock MFS High Yield Municipal Trust 111 Huntington Avenue Boston MA 02199 This Constitutes Amendment #11 to the schedule 13D filed July 17, 2023. Except as specifically set forth herein, the schedule 13D remains unmodified. As per the N-CSR filed on 1/23/26 there were 25,492,782 shares of common stock outstanding as of 11/30/25. The percentages set forth herein were derived using such number. Phillip Goldstein and Andrew Dakos own Bulldog Investors, LLP, a registered investment advisor. As of April 23, 2026, Bulldog Investors, LLP is deemed to be the beneficial owner of 2,814,161 shares of CMU (representing 11.04% of CMU's outstanding shares) solely by virtue of Bulldog Investors, LLP's power to direct the vote of, and dispose of, these shares. As of April 23, 2026, Mr. Goldstein is deemed to be the beneficial owner of 3,197,146 shares of CMU (representing 12.54% of CMU's outstanding shares) and Mr. Dakos is deemed to be the beneficial owner of 2,699,273 shares of CMU (representing 10.59% of CMU's outstanding shares) by virtue of their power to direct the vote of, and dispose of, these shares. Bulldog Investors, LLP has sole power to dispose of and vote 120,488 shares. Bulldog Investors, LLP has shared power to dispose and vote 2,693,673 shares. Certain of Bulldog Investors, LLP's clients (none of whom beneficially own more than 5% of CMU's shares) share this power with Bulldog Investors. Messrs. Goldstein and Dakos are partners of Bulldog Investors, LLP. Since the last filing on 4/9/26 the following shares of CMU were sold. Date Shares Price 4/23/2026 (20,694) 3.6676 4/22/2026 (24,260) 3.6600 4/21/2026 (35,000) 3.6752 4/20/2026 (22,500) 3.6700 4/17/2026 (1,500) 3.6800 4/16/2026 (2,571) 3.6700 4/15/2026 (110,000) 3.6700 4/14/2026 (5,192) 3.6600 Clients of Bulldog Investors, LLP and the owners of accounts reflected herein are entitled to receive any dividends or sales proceeds. N/A None None Bulldog Investors, LLP /s/ Andrew Dakos 04/24/2026 Phillip Goldstein /s/ Phillip Goldstein 04/24/2026 Andrew Dakos /s/ Andrew Dakos 04/24/2026