William P. Stiritz discloses 10.29% stake in Post Holdings (POST)

Rhea-AI Filing Summary

William P. Stiritz has updated his ownership disclosure for Post Holdings, Inc. He reports beneficial ownership of 4,885,468 shares of Post common stock, representing approximately 10.29% of the company’s outstanding shares as of March 4, 2026.

Stiritz holds 4,331,967 shares directly, 169,369 shares through The Wildwood Trust where he is trustee, and 384,132 shares through his spouse, Susan Stiritz, with whom he shares voting and disposition power on those shares.

The filing also notes a prior award of 2,700 restricted stock units granted on January 30, 2024, which vested on January 30, 2025 and will be settled in ten annual installments beginning six months after his December 16, 2025 retirement from the board, subject to acceleration upon a change in control or his death.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 4)

Post Holdings, Inc.

(Name of Issuer)

Common Stock, $0.01 par value

(Title of Class of Securities)

William P. Stiritz
790 Briar Hill Road,
Belleville, IL, 62223
6183987781

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

03/04/2026

(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).

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

William P. Stiritz

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)

PF, OO

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 4,501,336.00
8	Shared Voting Power 384,132.00
9	Sole Dispositive Power 4,501,336.00
10	Shared Dispositive Power 384,132.00

11

Aggregate amount beneficially owned by each reporting person

4,885,468.00

12

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

13

Percent of class represented by amount in Row (11)

10.3 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The percent ownership information included on line 13 above in this Amendment No. 4 to Schedule 13D is based on 47,475,676 shares of Common Stock, par value $0.01 per share, of Post Holdings, Inc., a Missouri corporation (the "Issuer"), issued and outstanding as of March 4, 2026, according to information provided by the Issuer.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, $0.01 par value
(b)	Name of Issuer: Post Holdings, Inc.
(c)	Address of Issuer's Principal Executive Offices: 2503 S. Hanley Rd, St. Louis, MISSOURI , 63144.
Item 1 Comment: EXPLANATORY NOTE - This Amendment No. 4 to Schedule 13D relates to the Schedule 13D filed by William P. Stiritz (the "Reporting Person") with the Securities and Exchange Commission (the "SEC") on December 1, 2016 (the "Initial Schedule 13D"), as amended by Amendment No. 1 to Schedule 13D filed with the SEC on February 22, 2021 ("Amendment No. 1"), Amendment No. 2 to Schedule 13D filed with the SEC on February 14, 2025 ("Amendment No. 2") and Amendment No. 3 to Schedule 13D filed with the SEC on October 15, 2025 ("Amendment No. 3," and the Initial Schedule 13D as amended by Amendment No. 1, Amendment No. 2 and Amendment No. 3, the "Schedule 13D"), and amends the Schedule 13D as specifically set forth herein.
Item 5.	Interest in Securities of the Issuer
(a)	Items 5(a)-(e) of the Schedule 13D are hereby amended and restated as follows: As of the date hereof, the Reporting Person beneficially owns, in the aggregate, 4,885,468 shares of Common Stock of the Issuer (the "Common Stock"), representing approximately 10.29% of the Issuer's outstanding shares of Common Stock. The Reporting Person beneficially owns shares of Common Stock of the Issuer directly (4,331,967 shares) and through The Wildwood Trust, of which the Reporting Person is Trustee (169,369 shares), and through his spouse, Susan Stiritz (384,132 shares).
(b)	The number of shares as to which there is sole power to vote or to direct the vote is 4,501,336. The number of shares as to which there is the shared power to vote or to direct the vote is 384,132. The number of shares as to which there is sole power to dispose or to direct the disposition is 4,501,336. The number of shares as to which there is shared power to dispose or to direct the disposition is 384,132. The Reporting Person shares voting and disposition rights with his spouse with respect to 384,132 shares. Susan Stiritz's address is 790 Briar Hill Road, Belleville, Illinois 62223. Mrs. Stiritz is retired and is a professor emeritus at Brown School at Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130. During the last five years, Mrs. Stiritz has not been convicted in a criminal proceeding. During the last five years, Mrs. Stiritz has not been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction which resulted in her being subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws. Mrs. Stiritz is a citizen of the United States.
(c)	The Reporting Person has effected no transactions in the Common Stock of the Issuer within the past sixty days.
(d)	Except for the Reporting Person's spouse, no person other than the Reporting Person has the right to receive dividends on, and any proceeds from the disposition of, any shares of Common Stock reported as owned by him in this Item 5 above.
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 of the Schedule 13D is hereby amended and restated as follows: On January 30, 2024, the Reporting Person was awarded 2,700 restricted stock units (the "2024 RSUs"). The 2024 RSUs vested on January 30, 2025. The Reporting Person elected to defer settlement of the 2024 RSUs such that settlement will occur in ten annual installments, beginning six months after Reporting Person's retirement from the Issuer's Board of Directors on December 16, 2025 (the "Retirement Date") and thereafter following each of the first nine anniversaries of the Retirement Date, subject to acceleration of all unpaid settlements upon the occurrence of a change in control or the death of the Reporting Person. Each 2024 RSU represents a right to receive one share of Common Stock, and the 2024 RSUs were awarded to the Reporting Person as a director of the Issuer, subject to a written agreement, the form of which was previously filed with the SEC by the Issuer and was previously referenced on the Schedule 13D in Item 7.

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.

William P. Stiritz

Signature:	/s/ William P. Stiritz
Name/Title:	William P. Stiritz
Date:	03/05/2026

FAQ

What percentage of Post Holdings (POST) does William P. Stiritz report owning?

William P. Stiritz reports beneficial ownership of approximately 10.29% of Post Holdings common stock. This equals 4,885,468 shares outstanding as of March 4, 2026, based on 47,475,676 shares issued and outstanding, according to information from the company.

How are William P. Stiritz’s Post Holdings (POST) shares held and structured?

William P. Stiritz directly owns 4,331,967 shares of Post Holdings. He also holds 169,369 shares through The Wildwood Trust, where he is trustee, and 384,132 shares are held by his spouse, over which they share voting and disposition power.

Did William P. Stiritz trade Post Holdings (POST) shares recently?

The amendment states that William P. Stiritz has effected no transactions in Post Holdings common stock within the past sixty days. This indicates his reported 10.29% stake reflects holdings that have not changed through recent market trades.

What voting and disposition powers does William P. Stiritz have over Post (POST) shares?

William P. Stiritz has sole voting and dispositive power over 4,501,336 shares of Post Holdings common stock. He shares voting and disposition power with his spouse, Susan Stiritz, over an additional 384,132 shares, bringing total beneficial ownership to 4,885,468 shares.

What restricted stock units related to Post Holdings (POST) has William P. Stiritz received?

On January 30, 2024, William P. Stiritz was awarded 2,700 restricted stock units. They vested on January 30, 2025. Each unit represents one Post share, with settlement deferred into ten annual installments starting six months after his December 16, 2025 board retirement.

Who is Susan Stiritz and what is her role in Post (POST) share ownership?

Susan Stiritz, William P. Stiritz’s spouse, holds 384,132 Post shares. William and Susan share voting and disposition rights over these shares. She is retired and a professor emeritus at Brown School at Washington University in St. Louis, and is a U.S. citizen.