Bulldog Investors (CMU) reports 5.42% beneficial stake in CMU

Rhea-AI Filing Summary

Bulldog Investors, LLP and its principals updated their ownership in MFS High Yield Municipal Trust (CMU) in this Amendment No. 13 to their Schedule 13D. As per an N-CSR, CMU had 25,492,782 common shares outstanding as of 11/30/25.

As of May 1, 2026, Bulldog Investors is deemed the beneficial owner of 1,382,344 shares of CMU, representing 5.42% of outstanding shares. Phillip Goldstein is deemed to beneficially own 1,765,329 shares (6.92%), and Andrew Dakos 1,267,456 shares (4.97%), based on their power to vote and dispose of these shares.

Bulldog Investors has sole voting and dispositive power over 120,488 shares and shared power over 1,261,856 shares, with certain clients sharing this power. Since the prior filing, CMU shares were sold on 4/30/26 and 5/1/26 in multiple trades, including blocks of 234,000 and 800,000 shares at prices around $3.64 per share.

Key Figures

Shares outstanding: 25,492,782 shares Bulldog beneficial ownership: 1,382,344 shares (5.42%) Goldstein beneficial ownership: 1,765,329 shares (6.92%) +4 more

7 metrics

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

Bulldog beneficial ownership 1,382,344 shares (5.42%) CMU shares deemed owned by Bulldog Investors as of 05/01/26

Goldstein beneficial ownership 1,765,329 shares (6.92%) CMU shares deemed owned by Phillip Goldstein as of 05/01/26

Dakos beneficial ownership 1,267,456 shares (4.97%) CMU shares deemed owned by Andrew Dakos as of 05/01/26

Sole voting/dispositive power 120,488 shares Shares over which Bulldog Investors has sole power

Shared voting/dispositive power 1,261,856 shares Shares over which Bulldog Investors has shared power

Largest disclosed sale 800,000 shares at $3.6448 CMU shares sold on 05/01/26

Key Terms

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

5 terms

beneficial owner financial

"Bulldog Investors, LLP is deemed to be the beneficial owner of 1,382,344 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.

Schedule 13D regulatory

"This Constitutes Amendment #13 to the Schedule 13D 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.

shared voting power financial

"Bulldog Investors, LLP has shared power to dispose and vote 1,261,856 shares"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

sole dispositive power financial

"Bulldog Investors, LLP has sole power to dispose of and vote 120,488 shares"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

investment advisor financial

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

An investment advisor is a person or firm that provides personalized guidance on buying, selling and managing investments and often oversees client portfolios for a fee. For investors this matters because the advisor shapes risk, costs and long-term returns, and is typically required by law to act in the client’s best interests — think of them as a financial coach or GPS that helps navigate choices and avoid costly detours.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 13)

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)

05/01/2026

(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 1,261,856.00
9	Sole Dispositive Power 120,488.00
10	Shared Dispositive Power 1,261,856.00

11

Aggregate amount beneficially owned by each reporting person

1,382,344.00

12

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

13

Percent of class represented by amount in Row (11)

5.42 %

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 1,644,841.00
9	Sole Dispositive Power 120,488.00
10	Shared Dispositive Power 1,644,841.00

11

Aggregate amount beneficially owned by each reporting person

1,765,329.00

12

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

13

Percent of class represented by amount in Row (11)

6.92 %

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 1,267,456.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,267,456.00

11

Aggregate amount beneficially owned by each reporting person

1,267,456.00

12

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

13

Percent of class represented by amount in Row (11)

4.97 %

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 #13 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 May 1, 2026, Bulldog Investors, LLP is deemed to be the beneficial owner of 1,382,344 shares of CMU (representing 5.42% 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 May 1, 2026, Mr. Goldstein is deemed to be the beneficial owner of 1,765,329 shares of CMU (representing 6.92% of CMU's outstanding shares) and Mr. Dakos is deemed to be the beneficial owner of 1,267,456 Shares of CMU (representing 4.97% 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 1,261,856 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 5/1/26 the following shares of CMU were sold. Date Shares Price 4/30/26 (234,000) 3.6512 4/30/26 (16,049) 3.6509 5/1/26 (25,000) 3.6431 5/1/26 (800,000) 3.6448
(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 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:	05/05/2026

Phillip Goldstein

Signature:	/s/ Phillip Goldstein
Name/Title:	Phillip Goldstein
Date:	05/05/2026

Andrew Dakos

Signature:	/s/ Andrew Dakos
Name/Title:	Andrew Dakos
Date:	05/05/2026

FAQ

What ownership stake does Bulldog Investors hold in CMU after this Schedule 13D/A?

Bulldog Investors, LLP is deemed to beneficially own 1,382,344 CMU shares, representing 5.42% of outstanding common stock as of May 1, 2026. This percentage is based on 25,492,782 shares outstanding as of 11/30/25 from the N-CSR filing.

How many CMU shares is Phillip Goldstein reported to beneficially own?

Phillip Goldstein is deemed to beneficially own 1,765,329 CMU shares, or 6.92% of the trust’s outstanding common stock. This ownership reflects his power to direct the vote and disposition of these shares as of May 1, 2026, including interests through Bulldog Investors.

What is Andrew Dakos’s reported beneficial ownership in CMU?

Andrew Dakos is deemed to beneficially own 1,267,456 CMU shares, equal to 4.97% of CMU’s outstanding common stock as of May 1, 2026. His ownership is attributed through his power to vote and dispose of shares associated with Bulldog Investors, LLP.

What CMU share sales are disclosed in this Schedule 13D amendment?

The filing lists CMU share sales on 4/30/26 and 5/1/26, including 234,000 shares at $3.6512, 16,049 at $3.6509, 25,000 at $3.6431, and 800,000 at $3.6448. These transactions update Bulldog Investors’ and its principals’ reported positions.

How many CMU shares did Bulldog Investors have sole and shared power over?

Bulldog Investors, LLP has sole voting and dispositive power over 120,488 CMU shares and shared power over 1,261,856 shares. Certain clients share this voting and dispositive power, but none individually beneficially own more than 5% of CMU’s outstanding shares.

What share count was used to calculate ownership percentages in this CMU filing?

Ownership percentages are based on 25,492,782 CMU common shares outstanding as of 11/30/25, taken from an N-CSR filed on 1/23/26. Bulldog Investors and its principals then applied this share count to derive their reported beneficial ownership percentages.