UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549

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FORM 8-K

CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 1, 2018

Post Holdings, Inc.

(Exact name of registrant as specified in its charter)

Missouri 1-35305 45-3355106 (State or other jurisdiction of (Commission File (IRS Employer Identification incorporation) Number) No.)

2503 S. Hanley Road St. Louis, Missouri 63144 (Address, including Zip Code, of principal executive offices)

Registrant’s telephone number, including area code: (314) 644-7600

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.05. Amendments to the Registrant’s Code of Ethics, or Waiver of a Provision of the Code of Ethics.

Post Holdings, Inc. (“Post”) has adopted a new Code of Conduct, effective as of October 1, 2018 (the “Code of Conduct”). The Code of Conduct is applicable to all directors, officers, and employees of Post, its subsidiaries and affiliates. The changes to the Code of Conduct include, among other things: (i) expanded provisions relating to compliance with anti-corruption and anti-bribery laws and other laws related to the transaction of business internationally; (ii) an expanded scope to include members of Post’s board of directors and (iii) other administrative and non-substantive amendments.

The amendment and restatement of the Code of Conduct did not relate to or result in any waiver, explicit or implicit, of any provision of the previous Code of Conduct. Any waivers under the Code of Conduct will be disclosed on a Current Report on Form 8-K or as otherwise permitted by the rules of the Securities and Exchange Commission and the New York Stock Exchange (or other stock exchange on which the Company’s securities are then listed). The new Code of Conduct is available on Post’s website at www.postholdings.com.

Item 7.01. Regulation FD Disclosure

On October 1, 2018, Post issued a press release announcing the completion of the previously announced transactions pursuant to the Transaction Agreement, dated as of August 2, 2018, among Post, its subsidiary 8th Avenue Food & Provisions, Inc. and THL Equity Fund VIII Investors (PB), LLC, an affiliate of Thomas H. Lee Partners, L.P.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

See Exhibit Index.

2 SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Date: October 1, 2018 Post Holdings, Inc. (Registrant)

By: /s/ Diedre J. Gray Name: Diedre J. Gray Title: EVP, General Counsel & Chief Administrative Officer, Secretary

3 EXHIBIT INDEX

Exhibit No. Description

99.1 Press Release, dated October 1, 2018.

4 Exhibit 99.1

Post Holdings, with Thomas H. Lee Partners, Announces Completion of Separate Capitalization of 8th Avenue Food & Provisions

St. Louis - October 1, 2018 - Post Holdings, Inc. (NYSE:POST) (“Post”), a consumer packaged goods holding company, announced today the completion of the previously announced agreement with Thomas H. Lee Partners, L.P. to separately capitalize 8th Avenue Food & Provisions, the holding company for Post’s private brands business, effective October 1, 2018.

About Post Holdings, Inc.

Post Holdings, Inc., headquartered in St. Louis, Missouri, is a consumer packaged goods holding company operating in the center-of-the-store, refrigerated, foodservice, food ingredient, and active nutrition food categories. Through its business, Post is a leader in the North American ready- to-eat cereal category offering a broad portfolio including recognized brands such as ®, Pebbles™, Great Grains® and Malt-O-Meal® bag cereal. Post also is a leader in the United Kingdom ready-to-eat cereal category with the iconic ® brand. As a leader in refrigerated foods, Post delivers innovative, value-added egg and refrigerated potato products to the foodservice channel and the retail refrigerated side dish category, offering side dishes and egg, sausage and cheese products through the Bob Evans®, Simply Potatoes®, All Whites®, Better’n Eggs® and Crystal Farms® brands. Post’s Active Nutrition platform brings good energy to a wide range of consumers looking to live healthy lives through brands such as Premier Protein®, PowerBar® and Dymatize®. Post participates in the private brand food category through its partnership with Thomas H. Lee Partners in 8th Avenue Food & Provisions, a leading, private brand centric, consumer products holding company. For more information, visit www.postholdings.com.

About Thomas H. Lee Partners, L.P.

Thomas H. Lee Partners, L.P. is a premier private equity firm investing in middle market growth companies, headquartered in North America, exclusively in four industry sectors: Business & Financial Services, Consumer & Retail, Healthcare, and Media, Information Services & Technology. Using the firm’s deep domain expertise and the internal operating capabilities of its Strategic Resource Group, THL seeks to create deal sourcing advantages, and to accelerate growth and improve operations in its portfolio companies in partnership with management teams. Since its founding in 1974, THL has raised over $25 billion of equity capital, acquired over 140 portfolio companies and completed over 360 add-on acquisitions which collectively represent a combined enterprise value at the time of acquisition of over $200 billion.

Contact: Post Media Relations Lisa Hanly [email protected] (314) 665-3180

Post Investor Relations Jennifer Meyer [email protected] (314) 644-7665