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: Borisy Alexis (Director)

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Series A-1 Preferred Stock	$		Common Stock (0)		Indirect
Series A-2 Preferred Stock	$		Common Stock (0)		Indirect
Series B Preferred Stock	$		Common Stock (0)		Indirect

Footnotes

F1: The Series A-1 Preferred Stock is convertible into Common Stock on a 2.6-for-one basis 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 Series A-1 Preferred Stock has no expiration date.

F2: Third Rock Ventures III, L.P. (the "Fund") holds 2,549,437, 2,021,269, and 85,470 shares of Series A-1, A-2 and Series B Preferred Stock of the Issuer on an as converted to Common Stock basis. The reporting person is a partner of Third Rock Ventures GP III, L.P., which is the general partner of the Fund. The reporting person disclaims beneficial ownership over such shares, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares.

F3: The Series A-2 Preferred Stock is convertible into Common Stock on a 2.6-for-one basis 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 Series A-2 Preferred Stock has no expiration date.

F4: The Series B Preferred Stock is convertible into Common Stock on a 2.6-for-one basis 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 Series B Preferred Stock has no expiration date.