Sec Form 4 Filing - Sanofi @ Translate Bio, Inc. - 2021-09-14

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 Sanofi 2. Issuer Name and Ticker or Trading Symbol Translate Bio, Inc. [ TBIO] 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) 54, RUE LA BOETIE 3. Date of Earliest Transaction (MM/DD/YY) 09/14/2021 (Street) PARIS, I075008 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, par value $0.001 per share 09/14/2021 P 51,467,612 ( 1 ) A $ 38 55,152,046 D Common Stock, par value $0.001 per share 09/14/2021 P 20,515,985 ( 2 ) A $ 38 75,668,031 ( 3 ) 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 (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 Sanofi 54, RUE LA BOETIE PARIS, I075008 X Signatures /s/ Alexandra Roger, as Head of Securities Law and Capital Markets of Sanofi 09/14/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Shares of Common Stock, par value $0.001 per share (the "Shares"), of Translate Bio, Inc. ("Translate Bio") acquired by Sanofi and its wholly-owned subsidiaries pursuant to the tender offer effected pursuant to the Agreement and Plan of Merger, dated as of August 2, 2021 (the "Merger Agreement"), by and among Sanofi, Vector Merger Sub, Inc., an indirect, wholly owned subsidiary of Sanofi ("Merger Sub"), and Translate Bio (such tender offer, the "Offer"). Prior to the Offer, Sanofi beneficially owned 3,684,434 Shares (approximately 4.87%). ( 2 )Reflects all of the outstanding Shares not tendered in the Offer and not owned by Sanofi or its wholly-owned subsidiaries prior to the Offer, which may be deemed to have been acquired pursuant to the consummation of the Merger (as defined below). Pursuant to the Merger, Sanofi now beneficially owns all outstanding Shares. ( 3 )Following the consummation of the Offer, Merger Sub was merged with and into Translate Bio, and Translate Bio survived the Merger as an indirect, wholly-owned subsidiary of Sanofi pursuant to a "back-end merger" under Delaware law (the "Merger"). Prior to the Merger, Sanofi indirectly held 100 shares of Merger Sub, which represented all of the issued and outstanding capital stock of Merger Sub. At the effective time of the Merger, all of the shares of Merger Sub were converted into 71,983,597 shares of Translate Bio stock.

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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