Sec Form 4 Filing - Polaris Venture Management Co. VI, L.L.C. @ Editas Medicine, Inc. - 2016-09-08

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 Polaris Venture Management Co. VI, L.L.C. 2. Issuer Name and Ticker or Trading Symbol Editas Medicine, Inc. [ EDIT] 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) ONE MARINA PARK DRIVE, 10TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/08/2016 (Street) BOSTON, MA02210 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 09/08/2016 S 500,000 D $ 16.8 4,156,173 I See Footnote ( 1 )

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 Polaris Ventur e Management Co. VI, L.L.C. ONE MARINA PARK DRIVE, 10TH FLOOR BOSTON, MA02210 X Polaris Venture Partners VI, L.P. 1000 WINTER STREET, SUITE 3350 WALTHAM, MA02451 X Polaris Venture Partners Founders' Fund VI, L.P. 1000 WINTER STREET, SUITE 3350 WALTHAM, MA02451 X Signatures /s/ Mary Blair, Attorney-in-Fact for Polaris Venture Management Co. VI, L.L.C. 09/12/2016 Signature of Reporting Person Date /s/ Mary Blair, Attorney-in-Fact for Polaris Venture Management Co. VI, L.L.C., the General Partner of Polaris Venture Partners VI, L.P. 09/12/2016 Signature of Reporting Person Date /s/ Mary Blair, Attorney-in-Fact for Polaris Venture Management Co. VI, L.L.C., the General Partner of Polaris Venture Partners Founders' Fund VI, L.P. 09/12/2016 Signature of Reporting Person Date

Explanation of Responses:

( 1 )3,926,710 of these shares are owned directly by Polaris Venture Partners VI, L.P. and 229,463 of the shares are owned by Polaris Venture Partners Founders' Fund VI, L.P. (together with Polaris Venture Partners VI, L.P., the "Polaris Funds"). Polaris Venture Management Co. VI, L.L.C. ("Polaris Management") is the general partner of each of the Polaris Funds. Kevin Bitterman, a member of the Board of Directors of the Issuer, has an assignee interest in Polaris Management. Each of Polaris Management and Mr. Bitterman disclaim beneficial ownership of all the shares owned by the Polaris Funds and this report shall not be deemed an admission that either is the beneficial owner of such shares for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interests therein.

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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