Sec Form 4 Filing - EQT Avatar Parent L.P. @ Certara, Inc. - 2021-03-29

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 EQT Avatar Parent L.P. 2. Issuer Name and Ticker or Trading Symbol Certara, Inc. [ CERT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O EQT PARTNERS, 1114 AVENUE OF THE AMERICAS, 45TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 03/29/2021 (Street) NEW YORK,, NY10036 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 03/29/2021 S 8,674,151 D $ 24.125 ( 1 ) 66,223,861 I Held by EQT Avatar Parent L.P. ( 2 )

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 EQT Avatar Parent L.P. C/O EQT PARTNERS 1114 AVENUE OF THE AMERICAS, 45TH FLOOR NEW YORK,, NY10036 X EQT Avatar Parent GP LLC C/O EQT PARTNERS 1114 AVENUE OF THE AMERICAS, 45TH FLOOR NEW YORK, NY10036 X EQT Fund Management S.a r.l. 26A, BOULEVARD ROYAL, LUXEMBOURG GRAND DUCHY OF LUXEMBOURG, N4L-2449 X Signatures EQT Avatar Parent L.P., By: EQT Avatar Parent GP LLC, as its general partner, By: /s/ Ethan Waxman, Name: Ethan Waxman Title: Vice President 03/30/2021 Signature of Reporting Person Date EQT Avatar Parent GP LLC, By: /s/ Ethan Waxman, Name: Ethan Waxman Title: Vice President 03/30/2021 Signature of Reporting Person Date EQT Fund Management S.a r.l., By: /s/ Nicholas Curwen, Name: Nicholas Curwen Title: Manager and /s/ Joshua Stone, Name: Joshua Stone Title: Manager 03/30/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This amount represents the $25.00 secondary public offering price per share of common stock of Certara, Inc., less the underwriting discount of $0.875 per share. ( 2 )Consists of shares of common stock held directly by EQT Avatar Parent L.P. ("EQT Investor"). EQT Avatar Parent GP LLC ("Avatar Parent GP") is the general partner of the EQT Investor. Several investment vehicles collectedly make up the fund known as "EQT VII." EQT VII owns 100% of the membership interests in Avatar Parent GP. EQT Fund Management S.a r.l. ("EFMS") has exclusive responsibility for the management and control of the business and affairs of investment vehicles which constitute the majority of the total commitments to EQT VII. As such, EFMS has the power to control Avatar Parent GP's voting and investment decisions and may be deemed to have beneficial ownership of the securities held by the EQT Investor.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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