Sec Form 3 Filing - WARBURG PINCUS & CO. @ Sotera Health Co - 2020-11-20

FORM 3 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 WARBURG PINCUS & CO. 2. Issuer Name and Ticker or Trading Symbol Sotera Health Co [ SHC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 450 LEXINGTON AVENUE, NEW YORK 3. Date of Earliest Transaction (MM/DD/YY) 11/20/2020 (Street) NY, NY100173147 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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") 118,929,897 I See Footnote ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) ( 7 ) ( 8 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other WARBURG PINCUS & CO. 450 LEXINGTON AVENUE NEW YORK NY, NY100173147 X X Warburg Pincus Private Equity XI, L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE 450 LEXINGTON AVENUE, NY10017 X X Warburg Pincus XI Partners, L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE NEW YORK, NY10017 X X Warburg Pincus Private Equity XI-B, L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE 450 LEXINGTON AVENUE, NY10017 X X Warburg Pincus Private Equity XI-C, L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE NEW YORK, NY10017 X X Bull Co-Invest L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE NEW YORK, NY10017 X X Warburg Pincus XI, L.P. C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE 450 LEXINGTON AVENUE, NY10017 X X WP Global LLC C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE NEW YORK, NY10017 X X Warburg Pincus Partners II (Cayman), L.P. 450 LEXINGTON AVENUE C/O WARBURG PINCUS LLC NEW YORK, NY10017 X X Warburg Pincus Partners GP LLC C/O WARBURG PINCUS LLC 450 LEXINGTON AVENUE NEW YORK, NY10017 X X Signatures /s/ Robert B. Knauss, Attorney-in-fact* for WP, the managing member of WPP GP LLC, the GP of WPP II, the managing member of WP Global, the GP of WP XI LP, the GP of Warburg Pincus Private Equity XI, L.P. 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for WP., the managing member of WPP GP LLC, the GP of WPP II, the MM of WP Global, the GP of WP XI LP, the general partner of Warburg Pincus XI Partners, L.P. 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WPP GP LLC, the general partner of WPP II, the managing member of WP Global, the general partner of WP XI LP, the general partner of WP XI Partners, L.P. 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for WP, the managing member of WPP GP LLC, the GP of WPP II, the managing member of WP Global, the GP of WP XI LP, the general partner of Warburg Pincus Private Equity XI-B, L.P. 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus (Bermuda), the GP of WPP II Cayman, the sole member of Warburg Pincus XI-C, LLC, the GP of Warburg Pincus (Cayman) XI, L.P., the GP of Warburg Pincus Private Equity XI-C, L.P 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WP Bull Manager, LLC, the general partner of Bull Co-Invest, L.P 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WPP GP LLC, the general partner of WPP II, the managing member of WP Global, the general partner of Warburg Pincus XI, L.P 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WPP GP LLC, the general partner of WPP II, the managing member of WP Global LLC 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WPP GP LLC, the general partner of WPP II 11/20/2020 Signature of Reporting Person Date /s/ Robert B. Knauss, Attorney-in-fact* for Warburg Pincus & Co., the managing member of WPP GP LLC 11/20/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 3 is being filed in connection with the effectiveness of the Registration Statement on Form 8-A relating to the registration under Section 12 of the Securities Exchange Act of 1934, as amended (the "Exchange Act") of Sotera Health Company (the "Issuer"). ( 2 )Includes 118,929,897 shares of Common Stock received as a liquidating distribution from Sotera Health Topco Parent, L.P. ("Topco Parent"). ( 3 )Warburg Pincus Private Equity XI, L.P., Warburg Pincus XI Partners, L.P., WP XI Partners, L.P., Warburg Pincus Private Equity XI-B, L.P. (collectively, the "WP XI Funds") are the holders of 94,872,693 shares of Common Stock of the Issuer. ( 4 )Qarburg Pincus Private Equity XI-C, L.P. ("WP XI-C") is the holder of 304,567 shares of Common Stock of the Issuer. ( 5 )Bull Co-Invest L.P., a Delaware limited partnership ("Bull Co-Invest") is the holder of 23,752,637 shares of Common Stock of the Issuer. ( 6 )Warburg Pincus XI, L.P., a Delaware limited partnership ("WP XI LP"), is the general partner of the WP XI Funds. WP Global LLC ("WP Global"), is the general partner of WP XI LP. Warburg Pincus Partners II, L.P. ("WPP II") is the managing member of WP Global. Warburg Pincus Partners GP LLC ("WPP GP LLC") is the general partner of WPP II. Warburg Pincus & Co. ("WP") is the managing member of WPP GP LLC. Warburg Pincus (Cayman) XI, L.P. ("WP Cayman") is the general partner of WP XI-C. Warburg Pincus XI-C, LLC ("Warburg Pincus XI-C") is the general partner of WP Cayman. Warburg Pincus Partners II (Cayman), L.P. ("WPP II Cayman") is the sole member of Warburg Pincus XI-C. Warburg Pincus (Bermuda) Private Equity GP Ltd. ("Warburg Pincus (Bermuda)") is the general partner of WPP II Cayman. WP Bull Manager, LLC ("WP Bull Manager") is the general partner of Bull Co-Invest. WP is the managing member of WP Bull Manager, LLC. ( 7 )Warburg Pincus LLC ("WP LLC") is the manager of the WP XI Funds and WP XI-C. The WP XI Funds, Bull Co-Invest, WP XI-C, WP XI LP, WP Global, WPP II, WPP GP LLC, WP Cayman, Warburg Pincus XI-C, WPP II Cayman, Warburg Pincus (Bermuda), WP Bull Manager, WP LLC and WP are collectively referred to herein as the "Warburg Pincus Entities." ( 8 )Each Warburg Pincus Entity disclaims beneficial ownership with respect to any shares of Common Stock of the Issuer, except to the extent of its pecuniary interest in such shares of Common Stock, if any. The WP XI Funds, WP XI-C, Bull Co-Invest, WP XI LP, WP Global, WPP II, WPP GP LLC, WP, WP Cayman, WPP II Cayman, Warburg Pincus (Bermuda), Warburg Pincus XI-C and WP Bull Manager are directors-by-deputization solely for purposes of Section 16 of the Exchange Act. Information with respect to each of the Warburg Pincus Entities is given solely by such Warburg Pincus Entity, and no Warburg Pincus Entity has responsibility for the accuracy or completeness of information supplied by another Warburg Pincus Entity.

Remarks: Form 1 of 2. Two reports are filed that relate to the same transactions. See Form 2 of 2 for additional reporting entities.

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 Inst ruction 4(b)(v).

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