Editas Medicine, Inc. — Director's Dealing 2016

Feb 2, 2016

SEC Form 3 — Initial Statement of Beneficial Ownership

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

Reporting Person: Bitterman Kevin (Director, 10% Owner)

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Series A-1 Preferred Stock	$		Common Stock (2549435)		Indirect
Series A-2 Preferred Stock	$		Common Stock (2021269)		Indirect
Series B Preferred Stock	$		Common Stock (85469)		Indirect

Footnotes

F1: The Series A-1 Preferred Stock is convertible into Common Stock on a 2.6-for-one basis into the number of shares shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have 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.

F3: The Series A-2 Preferred Stock is convertible into Common Stock on a 2.6-for-one basis into the number of shares shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.

F4: The Series B Preferred Stock is convertible into Common Stock on a 2.6-for-one basis into the number of shares shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.