SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response: 0.5

1. Name and Address of Reporting Person* VIKING GLOBAL INVESTORS LP (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 02/02/2016	3. Issuer Name and Ticker or Trading Symbol Editas Medicine, Inc. [ EDIT ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B Preferred Stock	(1)	(1)	Common Stock	1,709,401	(1)	I	See explanation of responses(2)(3)(4)(5)
Series B Preferred Stock	(1)	(1)	Common Stock	1,709,401	(1)	D(3)(5)

1. Name and Address of Reporting Person* VIKING GLOBAL INVESTORS LP (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Viking Global Opportunities Illiquid Investments Sub-Master LP (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Viking Global Opportunities Portfolio GP LLC (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Viking Global Opportunities GP LLC (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* HALVORSEN OLE ANDREAS (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Ott David C. (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Sundheim Daniel S. (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

Explanation of Responses:

1. Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, upon the closing of a firm commitment underwritten public offering in which the aggregate proceeds raised in the offering equal or exceed $50 million (the "IPO"), the Issuer's Series B Preferred Stock will be automatically converted into shares of common stock of the Issuer ("Common Stock"). The conversion ratio has been adjusted as a result of a one-for-2.6 reverse stock split of the Common Stock. The 4,444,444 shares of Series B Preferred Stock reported on this form will convert into 1,709,401 shares of Common Stock upon the closing of the IPO.

2. O. Andreas Halvorsen, David C. Ott and Daniel S. Sundheim are Executive Committee members of certain management entities, including Viking Global Partners LLC, the general partner of Viking Global Investors LP ("VGI"), and Viking Global Opportunities GP LLC ("Opportunities GP"), the sole owner of Viking Global Opportunities Portfolio GP LLC ("Opportunities Portfolio GP"). VGI provides managerial services to various investment funds, including Viking Global Opportunities Illiquid Investments Sub-Master LP ("Opportunities Fund"). Opportunities Portfolio GP is the general partner of Opportunities Fund. VGI, Opportunities GP, Opportunities Portfolio GP, Opportunities Fund, Mr. Halvorsen, Mr. Ott and Mr. Sundheim are collectively the "Reporting Persons." Each of the Reporting Persons may be deemed to beneficially own the shares reported on this form.

3. VGI provides managerial services to Opportunities Fund, which directly holds 4,444,444 shares of Series B Preferred Stock that will convert into 1,709,401 shares of Common Stock upon the closing of the IPO. Because of the relationship between VGI and Opportunities Fund, VGI may be deemed to beneficially own the shares of Series B Preferred Stock held directly by Opportunities Fund.

4. Opportunities Portfolio GP is the general partner of Opportunities Fund. Because of the relationship between Opportunities Portfolio GP and Opportunities Fund, Opportunities Portfolio GP may be deemed to beneficially own the shares of Series B Preferred Stock held directly by Opportunities Fund. Opportunities GP is the sole owner of Opportunities Portfolio GP. Because of the relationship between Opportunities GP and Opportunities Portfolio GP, Opportunities GP may be deemed to beneficially own the shares of Series B Preferred Stock held directly by Opportunities Fund.

5. The Reporting Persons disclaim beneficial ownership of these securities except to the extent of their pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purpose.

Remarks:

(6) The Reporting Persons are jointly filing this Form 3 pursuant to Rule 16a-3(j) under the Exchange Act. (7) Each of O. Andreas Halvorsen, David C. Ott and Daniel S. Sundheim is signing individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC and VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP.

	/s/ O. Andreas Halvorsen (6)(7)	02/02/2016
	/s/ David C. Ott (6)(7)	02/02/2016
	/s/ Daniel S. Sundheim (6)(7)	02/02/2016
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.