[SCHEDULE 13D/A] MFS High Yield Municipal Trust SEC Filing

Rhea-AI Filing Summary

The filing amends a Schedule 13D for MFS High Yield Municipal Trust (CMU) to report current beneficial ownership by Bulldog Investors, LLP and its partners. As of August 27, 2025, Bulldog Investors is deemed beneficial owner of 3,006,546 shares (11.79%) of CMU. Phillip Goldstein is deemed beneficial owner of 3,342,968 shares (13.11%) and Andrew Dakos of 2,896,773 shares (11.36%), based on 25,492,782 shares outstanding as of 11/30/24. The amendment lists purchased shares and prices between July 17, 2025 and August 27, 2025, including multiple purchases at prices around $3.22–$3.33 per share. Bulldog reports sole power over 109,810 shares and shared power over 2,896,773 shares.

Positive

• Material disclosed stake: Phillip Goldstein reported ownership of 3,342,968 shares (13.11%), a clearly material position.
• Transparent purchase history: Detailed list of purchases from 7/17/2025 to 8/27/2025 with share counts and execution prices (~$3.22–$3.33), enabling precise tracking of accumulation.
• Registered filing amendment: This is Amendment No. 7, indicating ongoing, updated compliance with reporting obligations.

Negative

• None.

Insights

Financial Analyst

TL;DR: A significant activist-sized stake reported; recent purchases modestly increased holdings around $3.22–$3.33 per share.

The filing documents that Phillip Goldstein and Bulldog Investors control a >11% stake and that Mr. Goldstein individually is reported at 13.11% of CMU. The transaction list shows steady incremental purchases over July–August 2025 at narrow price ranges, implying a buy program rather than a single block trade. The holding size exceeds typical passive thresholds, making this disclosure material to investors evaluating ownership concentration.

Corporate Governance Expert

TL;DR: Owners report shared voting/dispositive power; filings indicate partnership control rather than sole control of a large position.

The disclosure clarifies voting and dispositive powers: Bulldog Investors has sole power for a small parcel (109,810 shares) but shares control over the bulk position. Messrs. Goldstein and Dakos are partners in Bulldog Investors, which explains overlapping beneficial ownership figures. This structure is important for governance assessment because influence may be exercised collectively rather than by a single controlling actor.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 7)

MFS High Yield Municipal Trust

(Name of Issuer)

Common Stock

(Title of Class of Securities)

59318E102

(CUSIP Number)

Phillip Goldstein
250 Pehle Ave., Suite 708
Saddle Brook, NJ, 07663
914 747-5262

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/26/2025

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. 59318E102

1

Name of reporting person

Bulldog Investors, LLP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 109,810.00
8	Shared Voting Power 2,896,773.00
9	Sole Dispositive Power 109,810.00
10	Shared Dispositive Power 2,896,773.00

11

Aggregate amount beneficially owned by each reporting person

3,006,546.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

11.79 %

14

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13D

CUSIP No. 59318E102

1

Name of reporting person

Phillip Goldstein

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 109,810.00
8	Shared Voting Power 3,223,158.00
9	Sole Dispositive Power 109,810.00
10	Shared Dispositive Power 3,223,158.00

11

Aggregate amount beneficially owned by each reporting person

3,342,968.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

13.11 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP No. 59318E102

1

Name of reporting person

Andrew Dakos

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,896,773.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,896,773.00

11

Aggregate amount beneficially owned by each reporting person

2,896,773.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

11.36 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock
(b)	Name of Issuer: MFS High Yield Municipal Trust
(c)	Address of Issuer's Principal Executive Offices: 111 Huntington Avenue, 24th Floor, Boston, MASSACHUSETTS , 02199.
Item 1 Comment: This Constitutes Amendment #7 to the schedule 13D filed July 17, 2023. Except as specifically set forth herein, the schedule 13D rmains unmodified.
Item 5.	Interest in Securities of the Issuer
(a)	As per the N-CSR filed on 1/27/25 there were 25,492,782 shares of common stock outstanding as of 11/30/24. 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 August 27, 2025, Bulldog Investors, LLP is deemed to be the beneficial owner of 3,006,546 shares of CMU (representing 11.79% of CMU's outstanding shares) soley by virtue of Bulldog Investors, LLP's power to direct the vote of, and dispose of, these shares. As of August 27, 2025, Mr. Goldstein is deemed to be the beneficial owner of 3,342,968 shares of CMU (representing 13.11% of CMU's outstanding shares) and Mr. Dakos is deemed to be the beneficial owner of 2,896,773 shares of CMU (representing 11.36% of CMU's outstanding shares) by virtue of their power to direct the vote of, and dispose of, these shares.
(b)	Bulldog Investors, LLP has sole power to dispose of and vote 109,810 shares. Bulldog Investors, LLP has shared power to dispose and vote 2,896,773 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.
(c)	Since the last filing on 7/16/25 the following shares of CMU were purchased. Date Shares Price 8/27/2025 10,000 3.2800 8/26/2025 20,000 3.2783 8/22/2025 30,000 3.2800 8/21/2025 10,000 3.2667 8/20/2025 18,710 3.2860 8/19/2025 4,976 3.2798 8/18/2025 11,810 3.3279 8/08/2025 10,000 3.3200 8/05/2025 100 3.3100 8/04/2025 7,210 3.3098 8/01/2025 20,119 3.3093 7/31/2025 12,182 3.2700 7/29/2025 316 3.2500 7/28/2025 900 3.2400 7/25/2025 6,152 3.2400 7/24/2025 40,000 3.2400 7/23/2025 40,862 3.2200 7/22/2025 151 3.2300 7/21/2025 800 3.2200 7/18/2025 7,310 3.2188 7/17/2025 16,625 3.2361
(d)	Clients of Bulldog Investors, LLP and the owners of accounts reflected herein are entitled to receive any dividends or sales proceeds.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Bulldog Investors, LLP

Signature:	/s/ Andrew Dakos
Name/Title:	Andrew Dakos, Partner
Date:	08/28/2025

Phillip Goldstein

Signature:	/s/ Phillip Goldstein
Name/Title:	Phillip Goldstein, Partner
Date:	08/28/2025

Andrew Dakos

Signature:	/s/ Andrew Dakos
Name/Title:	Andrew Dakos, Partner
Date:	08/28/2025

FAQ

What percentage of CMU does Phillip Goldstein report owning?

The filing states Phillip Goldstein is deemed beneficial owner of 3,342,968 shares (13.11%) of CMU.

How many shares does Bulldog Investors, LLP report beneficially owning in CMU?

Bulldog Investors, LLP is deemed beneficial owner of 3,006,546 shares (11.79%) of CMU as of August 27, 2025.

What purchases were reported in the amendment and at what prices?

The amendment lists multiple purchases between 7/17/2025 and 8/27/2025, including blocks such as 40,000 shares at $3.24 (7/24/2025) and 20,119 shares at $3.3093 (8/1/2025), with prices in the range ~$3.22–$3.33.

Does Bulldog Investors hold sole voting power over all reported shares?

No. Bulldog Investors has sole voting power over 109,810 shares and shared voting power over 2,896,773 shares.

What is the reference share count used to calculate percentages?

Percentages are derived from 25,492,782 shares outstanding as reported in the N-CSR filed on 1/27/2025 reflecting 11/30/24 outstanding shares.