SEC Form 4

FORM 4		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 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Rayner Craig R. (Last) (First) (Middle) C/O CERTARA, INC. 100 OVERLOOK CENTER, SUITE 101 (Street) PRINCETON NJ 08540 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Certara, Inc. [ CERT ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) PRESIDENT, INTEGRATED DRUG DEV
	3. Date of Earliest Transaction (Month/Day/Year) 04/01/2021
	4. If Amendment, Date of Original Filed (Month/Day/Year) 04/09/2021	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	04/01/2021		A		38,462(1)	A	$0	479,396	D

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. The original Form 4, filed on April 9, 2021, is being amended by this Form 4 amendment solely to correct an administrative error, which misreported the number of restricted stock units granted on April 1, 2021 as a total of 23,810 restricted stock units being issued when in fact, 38,462 restricted stock units were issued. As a result of this administrative error, the number of shares beneficially owned by the reporting person following the corrected transaction reflects an increase in the number of shares as beneficially owned by the reporting person by 14,652 shares. All 38,462 restricted stock units received by the reporting person will vest, and the underlying shares of the issuer's common stock will be concurrently issued in a series of three equal installments upon the reporting person's completion of each 12 month period of service over the period measured from April 1, 2021 to April 1, 2024, subject to the continued service of the reporting person through such vesting dates.

	/s/ Richard M. Traynor, Attorney-in Fact for Craig R. Rayner	06/15/2021
	** Signature of Reporting Person	Date
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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