Perimeter Solutions, Inc.

10b5-1 Trading Plans

During the three months ended September 30, 2025, none of our officers (as defined in Rule 16a-1(f) of the Exchange Act) or directors adopted orterminated a "Rule 10b5-1 trading arrangement" or "non-Rule 10b5-1 trading arrangement," as each term is defined in Item 408(a) of Regulation S-K.

Updated Disclosure Regarding Director Terms

In our Definitive Proxy Statement for the 2025 Annual Meeting of Stockholders, we referenced the election of Messrs. Khouri and Raj as directors in June 2021, which occurred under Luxembourg law before the Redomiciliation Transaction, with terms expiring at the 2027 Annual Meeting of Stockholders, or until their respective successors are elected and qualified. On that basis, Messrs. Khouri and Raj were not nominated for election at the 2025 Annual Meeting of Stockholders. However, following the Redomiciliation Transaction, under Delaware law and our current certificate of incorporation, Messrs. Khouri and Raj must be nominated for election annually and, therefore will be nominated for election at the 2026 Annual Meeting of Stockholders and annually thereafter. Although we understand that, in the absence of the election of successors, Messrs. Khouri and Raj would currently remain directors of the Company, the Board has eliminated any uncertainty by adopting resolutions confirming Messrs. Khouri and Raj and appointing them to vacancies if they did not remain on the Board, as applicable.

Notice of Ratification of Corporate Acts

On October 29, 2025, the Board of Directors of the Company approved the ratification (the “Ratification”) under Section 204 of the General Corporation Law of the State of Delaware (“DGCL”) of the election of the initial board of directors of the Company (the “Initial Board”), which was contemplated in connection with the organization of the Company after the domestication and incorporation of the Company as a Delaware corporation pursuant to Section 108 of the DGCL. A copy of the resolutions adopted by the Board setting forth the information with respect to the Ratification required under Section 204 of the DGCL (the “Ratification Resolutions”) is attached hereto and incorporated herein as Exhibit 99.1.

Any claim that the “defective corporate acts” or “putative stock” (as such terms are defined in subsection (h) of Section 204) ratified pursuant to the Ratification Resolutions are void or voidable due to the failures of authorization set forth in the Ratification Resolutions or that the Court of Chancery of the State of Delaware should declare in its discretion that such ratifications in accordance with Section 204 not be effective or be effective only on certain conditions must be brought within 120 days from the later of the “validation effective time” (as such term is defined in subsection (h) of Section 204) or the time at which this notice is given.