Editas Medicine, Inc. — Director's Dealing 2016

Feb 10, 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: Flagship Ventures Fund IV, L.P. (10% Owner)
Reporting Person: Flagship Ventures Fund IV-Rx, L.P. (10% Owner)
Reporting Person: Flagship Ventures Fund IV General Partner LLC (10% Owner)
Reporting Person: KANIA EDWIN M JR (10% Owner)
Reporting Person: AFEYAN NOUBAR (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2016-02-08	Common Stock	C	2039549	—	Acquired	2039549	Direct
2016-02-08	Common Stock	C	1617015	—	Acquired	3656564	Direct
2016-02-08	Common Stock	C	307692	—	Acquired	3964256	Direct
2016-02-08	Common Stock	C	509885	—	Acquired	509885	Indirect
2016-02-08	Common Stock	C	404253	—	Acquired	914138	Indirect
2016-02-08	Common Stock	C	76922	—	Acquired	991060	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2016-02-08	Series A-1 Preferred Stock	$	C	5302834	Disposed		Common Stock (2039549)	Direct
2016-02-08	Series A-2 Preferred Stock	$	C	4204240	Disposed		Common Stock (1617015)	Direct
2016-02-08	Series B Preferred Stock	$	C	800001	Disposed		Common Stock (307692)	Direct
2016-02-08	Series A-1 Preferred Stock	$	C	1325708	Disposed		Common Stock (509885)	Indirect
2016-02-08	Series A-2 Preferred Stock	$	C	1051060	Disposed		Common Stock (404253)	Indirect
2016-02-08	Series B Preferred Stock	$	C	199999	Disposed		Common Stock (76922)	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 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: Held by Flagship Ventures Fund IV, L.P. ("Flagship IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship IV LLC") is the general partner of Flagship IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship IV LLC. Flagship IV LLC and each of these individuals may be deemed to share voting and investment power with respect to all shares held by Flagship IV. Each of the filing persons other than Flagship IV disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.

F3: Held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship IV-Rx"). Flagship IV LLC is the general partner of Flagship IV-Rx. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship IV LLC. Flagship IV LLC and each of these individuals may be deemed to share voting and investment power with respect to all shares held by Flagship IV-Rx. Each of the filing persons other than Flagship IV-Rx disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.