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Pay vs Performance Disclosure | 12 Months Ended
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Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Sep. 30, 2022 USD ($) | Sep. 30, 2021 USD ($)
Pay vs Performance Disclosure |  |  |  |  |
Pay vs Performance Disclosure, Table |
| Summary Compensation Table Total |  | Compensation Actually Paid |  |  | Value of Initial Fixed $100 Investment Based On:(4) |  |
Year | for Current PEO ($)(1) | for Interim PEO ($)(1) |  | to Current PEO ($)(1)(2)(3) | to Interim PEO ($)(1)(2)(3) | Average Summary Compensation Table Total for Non-PEO NEOs ($)(1) | Average Compensation Actually Paid to Non-PEO NEOs ($)(1)(2)(3) | TSR ($) | Peer Group TSR ($) | Net Income ($ in millions) | Adjusted EBITDA ($ in billions)(5)
2025 | 16,621,445 | — |  | 14,967,589 | — | 7,134,702 | 6,462,945 | 183.25 | 107.00 | 335.7 | 1.519
2024 | 21,963,675 | 6,978,110 |  | 44,585,899 | 14,455,262 | 5,814,851 | 12,307,458 | 197.35 | 126.32 | 366.7 | 1.404
2023 | 17,359,796 | — |  | 20,678,622 | — | 5,457,918 | 6,165,965 | 146.18 | 113.94 | 301.3 | 1.233
2022 | 15,475,418 | — |  | 19,312,412 | — | 4,470,515 | 5,922,265 | 139.65 | 111.28 | 756.6 | 0.964
2021 | 14,288,491 | — |  | 23,608,658 | — | 6,128,233 | 8,539,535 | 128.09 | 105.62 | 166.7 | 1.123
Company Selected Measure Name | Adjusted EBITDA |  |  |  |
Named Executive Officers, Footnote | Robert V. Vitale is our current principal executive officer (“PEO”) and was our PEO for the entirety of each fiscal year presented except for fiscal year 2024, during which he took a medical leave of absence from November 2, 2023 through January 30, 2024. During Mr. Vitale’s medical leave of absence in fiscal year 2024, Jeff A. Zadoks served as our interim PEO. The individuals comprising the Non-PEO NEOs for each fiscal year presented are listed below.
2021 | 2022 | 2023 | 2024 | 2025
Jeff A. Zadoks | Jeff A. Zadoks | Matthew J. Mainer | Matthew J. Mainer | Matthew J. Mainer
Howard A. Friedman | Nicolas Catoggio | Jeff A. Zadoks | Nicolas Catoggio | Nicolas Catoggio
Diedre J. Gray | Diedre J. Gray | Nicolas Catoggio | Diedre J. Gray | Diedre J. Gray
Mark W. Westphal | Mark W. Westphal | Diedre J. Gray | Mark W. Westphal | Jeff A. Zadoks
|  | Mark W. Westphal |  |
Peer Group Issuers, Footnote | The Peer Group TSR set forth in this table utilizes the S&P 1500 Packaged Foods & Meats Index, which we also utilize in the stock performance graph required by Item 201(e) of Regulation S-K included in our Annual Report on Form 10-K for the year ended September 30, 2025, filed with the SEC on November 21, 2025. The comparison assumes $100 was invested for the period starting September 30, 2020 through the end of the listed year in Post common stock (with reinvestment of shares of BellRing common stock distributed to Post shareholders on March 10, 2022) and in the S&P 1500 Packaged Foods & Meats Index, respectively. Historical stock performance is not necessarily indicative of future stock performance. |  |  |  |
Adjustment To PEO Compensation, Footnote |
Year | Summary Compensation Table Total for Current PEO ($) | Exclusion of Change in Pension Value for Current PEO ($) | Exclusion of Stock Awards for Current PEO ($) | Inclusion of Pension Service Cost for Current PEO ($) | Inclusion of Equity Values for Current PEO ($) | Compensation Actually Paid to Current PEO ($)
2025 | 16,621,445 | (261,532) | (14,811,295) | 129,984 | 13,288,987 | 14,967,589
Non-PEO NEO Average Total Compensation Amount | $ 7,134,702 |  |  |  |
Non-PEO NEO Average Compensation Actually Paid Amount | $ 6,462,945 |  |  |  |
Adjustment to Non-PEO NEO Compensation Footnote |
Year | Average Summary Compensation Table Total for Non-PEO NEOs ($) | Average Exclusion of Change in Pension Value for Non-PEO NEOs ($) | Average Exclusion of Stock Awards for Non-PEO NEOs ($) | Average Inclusion of Pension Service Cost for Non-PEO NEOs ($) | Average Inclusion of Equity Values for Non-PEO NEOs ($) | Average Compensation Actually Paid to Non-PEO NEOs ($)
2025 | 7,134,702 | (83,049) | (6,175,888) | 39,157 | 5,548,023 | 6,462,945
Equity Valuation Assumption Difference, Footnote | The amounts in the Inclusion of Equity Values columns in the tables above are derived from the amounts set forth in the following tables:
Year | Year-End Fair Value of Equity Awards Granted During Year that Remained Unvested as of Last Day of Year for Current PEO ($) | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Current PEO ($) | Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year for Current PEO ($) | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Current PEO ($) | Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year for Current PEO ($) | Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included for Current PEO ($) | Total - Inclusion of Equity Values for Current PEO ($)
2025 | 15,498,423 | (675,890) | — | (1,533,546) | — | — | 13,288,987
Year | Average Year-End Fair Value of Equity Awards Granted During Year that Remained Unvested as of Last Day of Year for Non-PEO NEOs ($) | Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs ($) | Average Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year for Non-PEO NEOs ($) | Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs ($) | Average Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year for Non-PEO NEOs ($) | Average Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included for Non-PEO NEOs ($) | Total - Average Inclusion of Equity Values for Non-PEO NEOs ($)
2025 | 6,180,686 | (219,275) | — | (413,388) | — | — | 5,548,023
Compensation Actually Paid vs. Total Shareholder Return | The following graph compares the Compensation Actually Paid to our current PEO, the Compensation Actually Paid to our former interim PEO, the average of the Compensation Actually Paid to our remaining NEOs, our cumulative TSR and the cumulative TSR of the S&P 1500 Packaged Foods & Meats Index over the five most recently completed fiscal years. The graph assumes a hypothetical investment of $100 on September 30, 2020 in each of Post common stock (with reinvestment of shares of BellRing common stock distributed to Post shareholders on March 10, 2022) and the S&P 1500 Packaged Foods & Meats Index. Post Holdings TSR & S&P 1500 Packaged Foods & Meats Index TSR vs. Compensation Actually Paid |  |  |  |
Compensation Actually Paid vs. Net Income | The following graph compares the Compensation Actually Paid to our current PEO, the Compensation Actually Paid to our former interim PEO and the average of the Compensation Actually Paid to our remaining NEOs with our net income during the five most recently completed fiscal years. Although required to be disclosed by SEC rules, net income is not a metric in our executive compensation program. Post Holdings Net Income vs. Compensation Actually Paid |  |  |  |
Compensation Actually Paid vs. Company Selected Measure | The following graph compares the Compensation Actually Paid to our current PEO, the Compensation Actually Paid to our former interim PEO and the average of the Compensation Actually Paid to our remaining NEOs with our Company-selected financial performance measure, Adjusted EBITDA, during the five most recently completed fiscal years. Post Holdings Adjusted EBITDA (our Company-Selected Financial Performance Measure) vs. Compensation Actually Paid |  |  |  |
Total Shareholder Return Amount | $ 183.25 | $ 197.35 | $ 146.18 | $ 139.65 | $ 128.09
Peer Group Total Shareholder Return Amount | 107.00 | 126.32 | 113.94 | 111.28 | 105.62
Net Income (Loss) | $ 335.7 | $ 366.7 | $ 301.3 | $ 756.6 | $ 166.7
Company Selected Measure Amount | 1.519 | 1.404 | 1.233 | 0.964 | 1.123
Additional 402(v) Disclosure | The amounts shown for Compensation Actually Paid have been calculated in accordance with Item 402(v) of Regulation S-K and do not reflect compensation actually earned, realized or received by the Company’s NEOs. These amounts reflect the Summary Compensation Table Total with certain adjustments as described in footnote 3 below. |  |  |  |
Measure:: 1 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Adjusted EBITDA |  |  |  |
Measure:: 2 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Segment Adjusted EBITDA - Post Consumer Brands |  |  |  |
Measure:: 3 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Relative Total Shareholder Return Percentile Rank (as compared to the Russell 3000 Packaged Foods & Meats companies) |  |  |  |
PEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
PEO Total Compensation Amount | $ 16,621,445 | $ 21,963,675 | $ 17,359,796 | $ 15,475,418 | $ 14,288,491
PEO Actually Paid Compensation Amount | $ 14,967,589 | 44,585,899 | 20,678,622 | 19,312,412 | 23,608,658
PEO Name | Robert V. Vitale |  |  |  |
PEO [Member] | Exclusion of Changes in Pension Value for PEO member [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | $ (261,532) |  |  |  |
PEO [Member] | Exclusion of Stock Awards for PEO member [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (14,811,295) |  |  |  |
PEO [Member] | Inclusion of Pension Service Cost for PEO member [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 129,984 |  |  |  |
PEO [Member] | Inclusion of Stock Award for PEO member [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 13,288,987 |  |  |  |
PEO [Member] | Year-End Fair Value of Equity Awards Granted During Year that Remained Unvested as of Last Day of Year for PEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 15,498,423 |  |  |  |
PEO [Member] | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (675,890) |  |  |  |
PEO [Member] | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (1,533,546) |  |  |  |
PEO [Member] | Total Inclusion of Equity Values for PEO member [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 13,288,987 |  |  |  |
Interim PEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
PEO Total Compensation Amount | 0 | 6,978,110 | 0 | 0 | 0
PEO Actually Paid Compensation Amount | 0 | $ 14,455,262 | 0 | 0 | 0
PEO Name |  | Jeff A. Zadoks |  |  |
Non-PEO NEO [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Non-PEO NEO Average Total Compensation Amount | 7,134,702 | $ 5,814,851 | 5,457,918 | 4,470,515 | 6,128,233
Non-PEO NEO Average Compensation Actually Paid Amount | 6,462,945 | $ 12,307,458 | $ 6,165,965 | $ 5,922,265 | $ 8,539,535
Non-PEO NEO [Member] | Average Exclusion of Changes in Pension Value for Non PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (83,049) |  |  |  |
Non-PEO NEO [Member] | Average Exclusion of Stock Awards for Non PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (6,175,888) |  |  |  |
Non-PEO NEO [Member] | Average Inclusion of Pension Service Cost for Non PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 39,157 |  |  |  |
Non-PEO NEO [Member] | Average Inclusion of Equity Values for Non PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 5,548,023 |  |  |  |
Non-PEO NEO [Member] | Average Year-End Fair Value of Equity Awards Granted During Year that Remained Unvested as of Last Day of Year for Non-PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 6,180,686 |  |  |  |
Non-PEO NEO [Member] | Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (219,275) |  |  |  |
Non-PEO NEO [Member] | Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | (413,388) |  |  |  |
Non-PEO NEO [Member] | Total Average Inclusion of Equity Values for Non-PEO NEOs [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | $ 5,548,023 |  |  |  |

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