X0306 4 2016-11-14 0 0001650664 Editas Medicine, Inc. EDIT 0001665594 Polaris Venture Management Co. VI, L.L.C. ONE MARINA PARK DRIVE, 10TH FLOOR BOSTON MA 02210 0 0 1 0 0001493463 Polaris Venture Partners VI, L.P. 1000 WINTER STREET, SUITE 3350 WALTHAM MA 02451 0 0 1 0 0001575691 Polaris Venture Partners Founders' Fund VI, L.P. 1000 WINTER STREET, SUITE 3350 WALTHAM MA 02451 0 0 1 0 Common Stock 2016-11-14 4 S 0 58035 17.16 D 4098138 I See Footnote Common Stock 2016-11-15 4 S 0 30367 16.55 D 4067771 I See Footnote Common Stock 2016-11-15 4 S 0 498 17.78 D 4067273 I See Footnote Represents 54,831 shares disposed of by Polaris Venture Partners VI, L.P. ("PVP VI") and 3,204 shares disposed of by Polaris Venture Partners Founders' Fund VI, L.P ("PVPFF VI"). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.00 to $17.51, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2),(5), and (8) to this Form 4. 3,871,879 of these shares are owned directly by PVP VI and 226,259 of the shares are owned by PVPFF VI (together with PVP VI, 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. Represents 28,689 shares disposed of by PVP VI and 1,678 shares disposed of by PVPFF VI. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.50 to $17.09, inclusive. 3,843,190 of these shares are owned directly by PVP VI and 224,581 of the shares are owned by PVPFF VI. 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. Represents 472 shares disposed of by PVP VI and 26 shares disposed of by PVPFF VI. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.50 to $17.86, inclusive. 3,842,718 of these shares are owned directly by PVP VI and 224,555 of the shares are owned by PVPFF VI. 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. Exhibit 24 - Power of Attorney /s/ Max Eisenberg, Attorney-in-Fact for Polaris Venture Management Co. VI, L.L.C. 2016-11-16 /s/ Max Eisenberg, Attorney-in-Fact for Polaris Venture Partners VI, L.P. 2016-11-16 /s/ Max Eisenberg, Attorney-in-Fact for Polaris Venture Partners Founders' Fund VI, L.P. 2016-11-16