Editas Medicine, Inc. — Director's Dealing 2016

Feb 9, 2016

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Editas Medicine, Inc. (EDIT)
CIK: 0001650664
Period of Report: 2016-02-08

Reporting Person: Polaris Venture Management Co. VI, L.L.C. (10% Owner)
Reporting Person: Polaris Venture Partners VI, L.P. (10% Owner)
Reporting Person: Polaris Venture Partners Founders' Fund VI, L.P. (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2016-02-08	Common Stock	C	2549435	—	Acquired	2549435	Indirect
2016-02-08	Common Stock	C	2021269	—	Acquired	4570704	Indirect
2016-02-08	Common Stock	C	85469	—	Acquired	4656173	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2016-02-08	Series A-1 Preferred Stock	$	C	6628542	Disposed		Common Stock (2549435)	Indirect
2016-02-08	Series A-2 Preferred Stock	$	C	5255300	Disposed		Common Stock (2021269)	Indirect
2016-02-08	Series B Preferred Stock	$	C	222222	Disposed		Common Stock (85469)	Indirect

Footnotes

F1: The Series A-1, Series A-2 and Series B Preferred Stock converted into Common Stock on a 2.6-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1, Series A-2 and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners VI, L.P. and 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 the Polaris Funds. Kevin Bitterman has an assignee interest in Polaris Management. Kevin Bitterman disclaims beneficial ownership of all the shares held by the Polaris Funds except to the extent of his pecuniary interest therein.