[SCHEDULE 13D/A] Post Holdings, Inc. SEC Filing

Rhea-AI Filing Summary

William P. Stiritz filed Amendment No. 3 to Schedule 13D reporting his beneficial ownership in Post Holdings, Inc. (POST). He reports aggregate beneficial ownership of 4,882,968 shares of common stock, representing approximately 9.28% of outstanding shares.

The filing details sole voting and dispositive power over 4,498,836 shares and shared voting and dispositive power over 384,132 shares with his spouse, Susan Stiritz. Holdings include 4,329,467 shares held directly, 169,369 shares through The Wildwood Trust, and 384,132 shares via his spouse.

The amendment notes an open‑market purchase of 36,000 shares at $109.53 per share on August 19, 2025. Post Holdings had 52,604,677 shares outstanding as of October 15, 2025.

Insights

Equity Ownership & Disclosure Analyst

Ownership update to 9.28% with recent open‑market buy.

William P. Stiritz updates his stake in Post Holdings to 9.28% of outstanding shares, totaling 4,882,968 shares. The structure shows concentrated control with sole voting and dispositive power over 4,498,836 shares and shared power over 384,132 shares with his spouse.

The filing cites an open‑market purchase of 36,000 shares at $109.53 on August 19, 2025, indicating recent incremental accumulation. Outstanding shares total 52,604,677 as of October 15, 2025, framing the ownership percentage within the current base.

While this is a standard 13D/A update, any future changes would depend on additional transactions or governance actions disclosed in subsequent amendments.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)

Post Holdings, Inc.

(Name of Issuer)

Common Stock, $0.01 par value

(Title of Class of Securities)

737446104

(CUSIP Number)

William P. Stiritz
790 Briar Hill Road,
Belleville, IL, 62223
618-398-7781

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

10/15/2025

(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. 737446104

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 4,498,836.00
8	Shared Voting Power 384,132.00
9	Sole Dispositive Power 4,498,836.00
10	Shared Dispositive Power 384,132.00

11

Aggregate amount beneficially owned by each reporting person

4,882,968.00

12

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

13

Percent of class represented by amount in Row (11)

9.3 %

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. 3 to Schedule 13D is based on 52,604,677 shares of Common Stock, par value $0.01 per share, of Post Holdings, Inc., a Missouri corporation (the "Issuer"), issued and outstanding as of October 15, 2025, 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. 3 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") and Amendment No. 2 to Schedule 13D filed with the SEC on February 14, 2025 ("Amendment No. 2" and the Initial Schedule 13D as amended by Amendment No. 1 and Amendment No. 2, 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, 4,882,968 shares of Common Stock of the Issuer (the "Common Stock"), representing approximately 9.28% of the Issuer's outstanding shares of Common Stock. The Reporting Person beneficially owns shares of Common Stock of the Issuer directly (4,329,467 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 4,498,836. 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 4,498,836. 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 of practice emeritus 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)	Other than the following, the Reporting Person has effected no transactions in the Common Stock of the Issuer within the past sixty days: On August 19, 2025, the Reporting Person purchased 36,000 shares of Common Stock of the Issuer in the open market for $109.53 per share.
(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.

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:	10/15/2025

FAQ

What stake in POST does William P. Stiritz report in this Schedule 13D/A?

He reports beneficial ownership of 4,882,968 shares, or approximately 9.28% of Post Holdings’ outstanding common stock.

Did William P. Stiritz buy additional POST shares recently?

Yes. On August 19, 2025, he purchased 36,000 shares in the open market at $109.53 per share.

How are voting and dispositive powers allocated in the POST stake?

He has sole power over 4,498,836 shares and shared power over 384,132 shares with his spouse.

How are Stiritz’s POST shares held?

They include 4,329,467 shares held directly, 169,369 shares via The Wildwood Trust, and 384,132 shares through his spouse.

What is POST’s total shares outstanding referenced in the filing?

The filing references 52,604,677 shares outstanding as of October 15, 2025.

What form and amendment is this disclosure for POST?

It is Amendment No. 3 to Schedule 13D for Post Holdings, Inc.