Sec Form 4 Filing - FORMELA JEAN FRANCOIS @ Translate Bio, Inc. - 2018-07-02

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 FORMELA JEAN FRANCOIS 2. Issuer Name and Ticker or Trading Symbol Translate Bio, Inc. [ TBIO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O TRANSLATE BIO, INC., 29 HARTWELL AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 07/02/2018 (Street) LEXINGTON, MA02421 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 07/02/2018 C 3,832,010 A 3,922,010 I By Atlas Venture Fund VIII, 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 Series A Preferred Stock ( 1 ) 07/02/2018 C 12,925,244 ( 1 ) ( 1 ) Common Stock 2,326,567 $ 0 0 I By Atlas Venture Fund VIII, L.P. ( 2 ) Series B Preferred Stock ( 1 ) 07/02/2018 C 5,838,230 ( 1 ) ( 1 ) Common Stock 1,050,891 $ 0 0 I By Atlas Venture Fund VIII, L.P. ( 2 ) Series C Preferred Stock ( 1 ) 07/02/2018 C 2,525,253 ( 1 ) ( 1 ) Common Stock 454,550 $ 0 0 I By Atlas Venture Fund VIII, L.P. ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other FORMELA JEAN FRANCOIS C/O TRANSLATE BIO, INC. 29 HARTWELL AVENUE LEXINGTON, MA02421 X Signatures /s/ Frank Castellucci, as attorney-in-fact for Jean-Francois Formela 07/03/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Series A, Series B and Series C Preferred Stock converted into Common Stock on a 5.5555-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A, Series B and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date. ( 2 )These shares are held directly by Atlas Venture Fund VIII, L.P. ("Atlas Venture Fund VIII"). The sole general partner of Atlas Venture Fund VIII is Atlas Venture Associates VIII, L.P. ("AVA VIII LP"). Atlas Venture Associates VIII, Inc. ("AVA VIII INC") is the sole general partner of AVA VIII LP. Dr. Formela is a director of AVA VIII INC and disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Fund VIII, except to the extent of his pecuniary interest therein, if any. This report shall not be deemed to be an admission that Dr. Formela is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

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