Bulldog Investors adjusts MFS High Yield Municipal (CMU) stake

Rhea-AI Filing Summary

Bulldog Investors, LLP and its principals Phillip Goldstein and Andrew Dakos filed Amendment No. 11 to their Schedule 13D for MFS High Yield Municipal Trust (CMU), updating their ownership and recent trading.

Using 25,492,782 shares outstanding as of 11/30/25, Bulldog Investors is deemed the beneficial owner of 2,814,161 CMU shares, or 11.04% of the fund. As of April 23, 2026, Mr. Goldstein is deemed to beneficially own 3,197,146 shares (12.54%), and Mr. Dakos 2,699,273 shares (10.59%), primarily through their interests in Bulldog Investors.

The amendment also reports recent CMU share sales between April 14 and April 23, 2026 at prices around $3.66–$3.68 per share, with dividends and sale proceeds for these shares payable to Bulldog Investors’ clients and account owners.

Key Figures

Shares outstanding: 25,492,782 shares Bulldog Investors ownership: 2,814,161 shares (11.04%) Phillip Goldstein ownership: 3,197,146 shares (12.54%) +3 more

6 metrics

Shares outstanding 25,492,782 shares CMU common stock outstanding as of 11/30/25

Bulldog Investors ownership 2,814,161 shares (11.04%) Beneficial ownership of CMU as of 04/23/26

Phillip Goldstein ownership 3,197,146 shares (12.54%) Beneficial ownership of CMU as of 04/23/26

Andrew Dakos ownership 2,699,273 shares (10.59%) Beneficial ownership of CMU as of 04/23/26

Largest single-day sale 110,000 shares at $3.6700 CMU shares sold on 04/15/2026

Recent sale price range $3.6600–$3.6800 CMU trades from 04/14/2026 to 04/23/2026

Key Terms

Schedule 13D, beneficial owner, sole voting power, shared dispositive power, +1 more

5 terms

Schedule 13D regulatory

"This Constitutes Amendment #11 to the filed July 17, 2023."

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

beneficial owner financial

"Bulldog Investors, LLP is deemed to be the beneficial owner of 2,814,161 shares"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

sole voting power financial

"Sole Voting Power 120,488.00"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

shared dispositive power financial

"Shared Dispositive Power 2,693,673.00"

registered investment advisor financial

"Phillip Goldstein and Andrew Dakos own Bulldog Investors, LLP, a registered investment advisor."

A registered investment advisor is a professional or firm that provides financial advice and manages investments for clients, operating under regulations that require them to act in their clients' best interests. This designation helps investors identify trustworthy advisors who are legally committed to providing transparent and fair guidance, much like a licensed doctor is bound to prioritize patient well-being.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 11)

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)

04/23/2026

(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).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 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 120,488.00
8	Shared Voting Power 2,693,673.00
9	Sole Dispositive Power 120,488.00
10	Shared Dispositive Power 2,693,673.00

11

Aggregate amount beneficially owned by each reporting person

2,814,161.00

12

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

13

Percent of class represented by amount in Row (11)

11.04 %

14

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13D

CUSIP Number(s): 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 120,488.00
8	Shared Voting Power 3,076,658.00
9	Sole Dispositive Power 120,488.00
10	Shared Dispositive Power 3,076,658.00

11

Aggregate amount beneficially owned by each reporting person

3,197,146.00

12

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

13

Percent of class represented by amount in Row (11)

12.54 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP Number(s): 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 2,699,273.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,699,273.00

11

Aggregate amount beneficially owned by each reporting person

2,699,273.00

12

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

13

Percent of class represented by amount in Row (11)

10.59 %

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, Boston, MASSACHUSETTS , 02199.
Item 1 Comment: This Constitutes Amendment #11 to the schedule 13D filed July 17, 2023. Except as specifically set forth herein, the schedule 13D remains unmodified.
Item 5.	Interest in Securities of the Issuer
(a)	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.
(b)	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.
(c)	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
(d)	Clients of Bulldog Investors, LLP and the owners of accounts reflected herein are entitled to receive any dividends or sales proceeds.
(e)	N/A
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	None
Item 7.	Material to be Filed as Exhibits.
	None

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:	04/24/2026

Phillip Goldstein

Signature:	/s/ Phillip Goldstein
Name/Title:	Phillip Goldstein
Date:	04/24/2026

Andrew Dakos

Signature:	/s/ Andrew Dakos
Name/Title:	Andrew Dakos
Date:	04/24/2026

FAQ

What ownership in CMU does Bulldog Investors report in this Schedule 13D/A?

Bulldog Investors, LLP reports beneficial ownership of 2,814,161 CMU shares, equal to 11.04% of outstanding shares. This percentage is based on 25,492,782 shares of CMU common stock outstanding as of November 30, 2025, per the issuer’s N-CSR.

How many CMU shares does Phillip Goldstein report owning in this filing?

Phillip Goldstein is deemed to beneficially own 3,197,146 CMU shares, representing 12.54% of the fund’s outstanding common stock. His beneficial ownership stems from his power to direct the vote and disposition of these shares through interests including Bulldog Investors, LLP.

What CMU stake does Andrew Dakos report in the amended Schedule 13D?

Andrew Dakos is deemed to beneficially own 2,699,273 CMU shares, or 10.59% of shares outstanding. He has shared voting and dispositive power over these shares through his role as a partner of Bulldog Investors, LLP and related accounts.

What recent CMU share sales are disclosed by Bulldog Investors and its principals?

The filing lists CMU sales from April 14–23, 2026, including trades such as 110,000 shares at $3.6700 on April 15 and 35,000 shares at $3.6752 on April 21. These transactions reduce their position while keeping ownership above 10%.

What share count was used to calculate CMU ownership percentages in this 13D/A?

Ownership percentages are based on 25,492,782 CMU shares outstanding as of November 30, 2025. That figure comes from the issuer’s N-CSR filed January 23, 2026, and is used to derive the reported 11.04%, 12.54%, and 10.59% stakes.

Who receives dividends and sale proceeds from the CMU shares held by Bulldog Investors?

According to the filing, clients of Bulldog Investors, LLP and the owners of the accounts reflected in the report are entitled to receive any dividends or sale proceeds from the CMU shares over which Bulldog has voting and dispositive power.