Sec Form 4 Filing - Petras Michael B. Jr. @ Sotera Health Co - 2024-03-02

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Petras Michael B. Jr. 2. Issuer Name and Ticker or Trading Symbol Sotera Health Co [ SHC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chairman & CEO (Last) (First) (Middle) C/O SOTERA HEALTH COMPANY, 9100 SOUTH HILLS BLVD, SUITE 300 3. Date of Earliest Transaction (MM/DD/YY) 03/02/2024 (Street) BROADVIEW HEIGHTS, OH44147 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, $0.01 par value per share ("Common Stock") 03/02/2024 F 27,990 ( 1 ) D $ 14.56 447,163 D Common Stock, $0.01 par value per share ("Common Stock") 03/02/2024 F 21,574 ( 2 ) D $ 14.56 425,589 D Common Stock, $0.01 par value per share ("Common Stock") 03/04/2024 A 274,160 ( 3 ) A $ 0 699,749 ( 4 ) D Common Stock, $0.01 par value per share ("Common Stock") 03/04/2024 S 1,003,870 ( 5 ) D $ 14.3075 ( 6 ) 5,453,580 I By Grantor Trust

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Options $ 14.59 03/04/2024 A 544,509 ( 7 ) 03/04/2034 Common Stock 544,509 $ 0 544,509 ( 7 ) D Stock Options ( 8 ) $ 17.59 ( 9 ) 03/06/2033 Common Stock 404,094 404,094 D Stock Options ( 8 ) $ 6.37 ( 10 ) 11/07/2032 Common Stock 2,108,356 2,108,356 D Stock Options ( 8 ) $ 20.03 ( 11 ) 03/02/2032 Common Stock 478,932 478,932 D Stock Options ( 8 ) $ 23 ( 12 ) 11/20/2030 Common Stock 1,118,012 1,118,012 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Petras Michael B. Jr. C/O SOTERA HEALTH COMPANY 9100 SOUTH HILLS BLVD, SUITE 300 BROADVIEW HEIGHTS, OH44147 Chairman & CEO Signatures Matthew J. Klaben, Attorney-in-Fact 03/05/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These securities represent the number of shares of Common Stock withheld by the Issuer to satisfy the Reporting Person's tax withholding obligations due upon the vesting of 62,406 Restricted Stock Units ("RSUs"), which represents 33% of the RSU award granted to the Reporting Person on March 2, 2022. This award was granted pursuant to the terms of an RSU agreement under the Sotera Health Company 2020 Omnibus Incentive Plan ("2020 Incentive Plan"). Each RSU represents the Reporting Person's right to receive one share of Common Stock, subject to vesting conditions. ( 2 )These securities represent the number of shares of Common Stock withheld by the Issuer to satisfy the Reporting Person's tax withholding obligations due upon the vesting of 71,063 RSUs, which represents 33% of the RSU award granted to the Reporting Person on March 6, 2023. This award was granted pursuant to the terms of an RSU agreement under the 2020 Incentive Plan. Each RSU represents the Reporting Person's right to receive one share of Common Stock, subject to vesting conditions. ( 3 )These securities consist of RSUs that were granted on March 4, 2024, pursuant to the terms of an RSU agreement under the 2020 Incentive Plan. Each RSU represents the Reporting Person's right to receive one share of Common Stock, subject to vesting conditions. The RSUs vest annually in three equal installments commencing March 2, 2025. ( 4 )These securities consist of 543,910 RSUs and 155,839 shares of Common Stock. ( 5 )On March 4, 2024, the Reporting Person sold a total of 1,003,870 shares of Common Stock of the Issuer in an underwritten public secondary offering (the "Offering"). ( 6 )Reflects a price equal to the Offering price per share less underwriting discounts and commissions payable thereon, as disclosed in the Issuer's Prospectus 424(b)(7), filed with the United States Securities and Exchange Commission on February 29, 2024. ( 7 )These options were granted on March 4, 2024, pursuant to the terms of a stock option agreement under the 2020 Incentive Plan. The options vest annually in three equal installments commencing March 2, 2025, subject to vesting conditions. ( 8 )No transaction is being reported on this line. Reported on a previously filed Form 4. ( 9 )These options were granted on March 6, 2023, pursuant to the terms of a stock option agreement under the 2020 Incentive Plan. The options vest annually in three equal installments commencing March 2, 2024, subject to vesting conditions. ( 10 )These options were granted on November 7, 2022, pursuant to the terms of a stock option agreement under the 2020 Incentive Plan. The options vest in three installments, as follows: 30%, 30%, and 40% of the options vest on each of the 12-month, 18-month, and 24-month anniversaries, respectively, of the date of grant, subject to the Reporting Person's continued service through each such date. ( 11 )These options were granted on March 2, 2022, pursuant to the terms of a stock option agreement under the 2020 Incentive Plan. The options vest in three equal installments on each of the first three anniversaries of the date of grant, subject to vesting conditions. ( 12 )These options were granted on November 20, 2020, pursuant to the terms of a stock option agreement under the 2020 Incentive Plan. The options vest in four equal installments on each of the first four anniversaries of the date of grant, subject to vesting conditions.

Remarks: The Power of Attorney for Mr. Petras is filed as an exhibit to the Form 3 filed on November 20, 2020, which is hereby incorporated by reference.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b )(v).

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