Sotera Health Co

Rule 10b5-1 Trading Plans

During the three months ended September 30, 2024, none of the Company’s directors or officers (as defined in Rule 16a-1(f) under the Exchange Act)adopted orterminated any contract, instruction or written plan for the purchase or sale of Company securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any “non-Rule 10b5-1 trading arrangement” (as that term is defined in Regulation S-K, Item 408).

Amended and Restated Bylaws

As part of a broader review of its governance practices and in response to amendments to the federal proxy rules adopted by the SEC, on November 4, 2024, the Board of Directors of the Company, acting upon the recommendation of the Nominating and Corporate Governance Committee of the Board, approved the amendment and restatement of the Company’s Amended and Restated Bylaws, effective as of such date (as amended and restated, the “Amended and Restated Bylaws”).

The Amended and Restated Bylaws, among other things:

•address matters relating to Rule 14a-19 under the Exchange Act, as amended (the “Universal Proxy Rule”), including requiring that any stockholder submitting a nomination notice make a representation as to whether such stockholder intends to solicit proxies in support of director nominees other than the Company’s nominees in accordance with the Universal Proxy Rule;

•require additional disclosures and acknowledgments from nominating or proposing stockholders, proposed nominees and associated persons, including regarding compliance with the Universal Proxy Rule with respect to nominating stockholders;

•enhance the existing procedural mechanics in connection with stockholder nominations of directors and submission of stockholder proposals made in connection with meetings of stockholders;

•require that any stockholder directly or indirectly soliciting proxies from other stockholders use a proxy card color other than white, with the white proxy card being reserved for exclusive use by the Board;

•require that any proposed director nominee submit to interviews with the Board or a committee;

•modify the provisions relating to the adjournment procedures for meetings of stockholders to reflect recent amendments to the General Corporation Law of the State of Delaware; and

•incorporate certain administrative, modernizing, clarifying, and conforming changes.

The foregoing general description of the Amended and Restated Bylaws is qualified in its entirety by reference to the full text of the Amended and Restated Bylaws, which are attached as Exhibit 3.1 to this Quarterly Report on Form 10-Q and are incorporated by reference herein.