MHI: Sit Investment tops 10% ownership with 2.6M shares filed

Rhea-AI Filing Summary

Sit Investment Associates, Inc. (SIA) and its subsidiary Sit Fixed Income Advisors II, LLC (SFI) have jointly filed Amendment No. 1 to Schedule 13G for Pioneer Municipal High Income Fund, Inc. (MHI). As of 31 Jul 2025, the advisers report beneficial ownership of 2,614,270 common shares, equal to 11.5 % of the 22,771,349 shares outstanding.

The stake is held entirely through client accounts; SIA and SFI assert shared voting and dispositive power over the shares and disclaim any direct economic ownership under Rule 13d-4. Both entities are registered investment advisers (Item 3 class “IA”) and certify the holdings were acquired in the ordinary course of business without intent to influence control of the issuer. Paul E. Rasmussen, Vice President, signed on 05 Aug 2025.

No other persons or subsidiaries are identified as part of a group, and there are no disclosures of transactions, sales, or ownership below 5 %.

Positive

• Institutional ownership exceeds 10 %, with SIA/SFI reporting 2.61 million shares (11.5 %), highlighting professional confidence in MHI.

Negative

• None.

Insights

Financial Analyst

TL;DR: Passive advisers now hold 11.5 % of MHI, signaling institutional interest but no control intent.

The combined SIA/SFI position crosses the 10 % threshold, requiring this 13G update. Because the advisers act on behalf of client accounts and expressly disclaim ownership intent, the filing is informational rather than strategic. The disclosure may be modestly supportive for valuation by highlighting demand from a reputable fixed-income manager, yet it does not indicate activism, takeover risk, or capital changes. Market impact should be limited unless future amendments show material position shifts.

Portfolio Manager

TL;DR: An 11.5 % passive stake by Sit enhances float stability and signals confidence in tax-exempt high-yield strategy.

SIA/SFI’s sizable, jointly controlled position can reduce near-term share overhang and improve liquidity as the advisers are long-term, income-focused investors. While not activist, their presence may marginally tighten the free float, potentially aiding NAV discount narrowing if other buyers follow. However, because the shares are held for multiple discretionary accounts, block exits remain possible over time.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Pioneer Municipal High Income Fund, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

723763108

(CUSIP Number)

07/31/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 723763108

1

Names of Reporting Persons

Sit Investment Associates, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MINNESOTA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,614,270.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,614,270.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,614,270.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.5 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP No. 723763108

1

Names of Reporting Persons

Sit Fixed Income Advisors II, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,614,270.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,614,270.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,614,270.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.5 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Pioneer Municipal High Income Fund, Inc.
(b)	Address of issuer's principal executive offices: 60 State Street, Boston, MA 02109
Item 2.
(a)	Name of person filing: Sit Investment Associates, Inc. Sit Fixed Income Advisors II, LLC
(b)	Address or principal business office or, if none, residence: 80 South Eighth Street, Suite 3300 Minneapolis, MN 55402
(c)	Citizenship: Sit Investment Associates, Inc. Minnesota Corporation Sit Fixed Income Advisors II, LLC Delaware LLC
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 723763108
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: See response to item 9 on each cover page.
(b)	Percent of class: See response to item 11 on each cover page.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See response to item 5 on each cover page.
	(ii) Shared power to vote or to direct the vote: See response to item 6 on each cover page.
	(iii) Sole power to dispose or to direct the disposition of: See response to item 7 on each cover page.
	(iv) Shared power to dispose or to direct the disposition of: See response to item 8 on each cover page. The ownership percentages reported are based on 22,771,349 shares of common stock outstanding as of April 30, 2025, as reported in the Issuer's Report on Form N-CSR filed with the Securities Exchange Commission. Sit Investment Associates, Inc. ("SIA") is an investment adviser registered under section 203 of the Investment Advisers Act of 1940. Sit Fixed Income Advisors II, LLC ("SFI") is an investment adviser registered under section 203 of the Investment Advisers Act of 1940 and a subsidiary of SIA. SIA and SFI provide investment management services to client accounts ("Accounts"). In their roles as investment advisers SIA and SFI possess shared voting and investment power over securities of the Issuer described in this schedule 13G owned by the Accounts and may be deemed to be the beneficial owner of such shares of the Issuer owned by the Accounts. All securities reported in this schedule 13G are owned by the Accounts. Pursuant to Rule 13d-4 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), SIA and SFI disclaim beneficial ownership of such securities.
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Accounts are known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities. Except as may be indicated if this is a joint filing with a registered investment company managed by SIA or SFI, not more than 5% of the class of such securities is owned by any one Account subject to the investment advice of SIA or SFI.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

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.

Sit Investment Associates, Inc.

Signature:	/s/ Paul E. Rasmussen
Name/Title:	Paul Rasmussen / Vice President
Date:	08/05/2025

Sit Fixed Income Advisors II, LLC

Signature:	/s/ Paul E. Rasmussen
Name/Title:	Paul Rasmussen / Vice President
Date:	08/05/2025

Exhibit Information

Exhibit A - Joint Filing Agreement

FAQ

How many MHI shares do Sit Investment Associates and Sit Fixed Income Advisors II jointly own?

They report beneficial ownership of 2,614,270 common shares.

What percentage of Pioneer Municipal High Income Fund’s outstanding stock does this represent?

The holding equals 11.5 % of the 22,771,349 shares outstanding.

Do Sit Investment Associates and its subsidiary have sole or shared voting power over the MHI shares?

They have shared voting and dispositive power; sole power is 0.

Is the filing activist in nature?

No. The advisers certify the stake was acquired in the ordinary course and not to influence control of the issuer.

When was the event date triggering this Schedule 13G amendment?

The event date is 31 July 2025.

What is the classification of the reporting persons under SEC rules?

Both entities are classified as Investment Advisers (IA) under Item 3.