Sotera Health Co

Rule 10b5-1 Trading Plans

During the three months ended December 31, 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).

Offer Letter Revision and Retention Awards

The Company is currently a party to an offer letter, dated February 26, 2024, with Mr. Jonathan Lyons, the Company’s Chief Financial Officer, which offer letter generally provides for certain of his initial and ongoing compensation and benefits arrangements with the Company. On February 26, 2025, the Company entered into an amendment and restatement of the offer letter, primarily to revise the terms of Mr. Lyons’ entitlement to cash severance benefits under the offer letter. Under the amendment and restatement, the Company increased the amount of such cash severance benefits from one times his annual base salary rate to one times the sum of his annual base salary rate plus his target short-term annual incentive. Further, on March 3, 2025, the Company intends to provide to Mr. Lyons (1) a $500,000 cash-based retention award that will vest as to 10% of the award on the 6-month anniversary of the grant date, 20% of the award on the 12-month anniversary of the grant date, 30% of the award on the 18-month anniversary of the grant date and the remaining amount of the award on the 24-month anniversary of the grant date, in each case generally subject to Mr. Lyons’ continued service with the Company through the applicable vesting date, as well as (2) a retention grant of $500,000 in time-based restricted stock units, which award will, in general, vest as to 50% of the award on the first anniversary of the grant date and the remaining amount of the award on the second anniversary of the grant date, in each case subject to Mr. Lyons’ continued service with the Company through the applicable vesting date. The vesting of the time-based restricted stock units award will accelerate if Mr. Lyons’ service ceases due to his death or disability, or under certain conditions regarding a change in control of the Company (as described in the applicable award agreement).