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: Borisy Alexis (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2016-02-08	Common Stock	C	0	—	Acquired	0	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2016-02-08	Series A-1 Preferred Stock	$	C	0	Disposed		Common Stock (0)	Indirect
2016-02-08	Series A-2 Preferred Stock	$	C	0	Disposed		Common Stock (0)	Indirect
2016-02-08	Series B Preferred Stock	$	C	0	Disposed		Common Stock (0)	Indirect

Footnotes

F1: Represents 4,656,176 shares held by Third Rock Ventures III, L.P. (the "Fund") received by the Fund upon conversion of Series A-1, Series A-2 and Series B Preferred Stock upon closing of the Issuer's initial public offering.

F2: 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 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 Preferred Stock had no expiration date.

F3: 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 the shares held by the Fund, 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.

F4: Prior to the conversion, the Fund held 6,628,542 shares of Series A-1 Preferred Stock, 5,255,300 shares of Series A-2 Preferred Stock and 222,222 shares of Series B Preferred Stock.

F5: Prior to the conversion, the shares of Common Stock underlying Series A-1, Series A-2 and Series B Preferred Stock held by the Fund were 2,549,437, 2,021,269 and 85,470, respectively.