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

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1. Name and Address of Reporting Person* VIKING GLOBAL PERFORMANCE LLC (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 02/08/2016	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)
Common Stock	1,020,407	I	See explanation of responses(1)(2)(3)(4)(5)(6)(7)
Common Stock	256,986	D(2)(5)(6)
Common Stock	15,072	D(2)(5)(7)
Common Stock	481,567	D(2)(5)(6)
Common Stock	266,782	D(2)(5)(6)(7)

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

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

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

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

1. Name and Address of Reporting Person* VGE III Portfolio Ltd. (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Viking Long Fund Master Ltd. (Last) (First) (Middle) 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

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

Explanation of Responses:

1. O. Andreas Halvorsen, David C. Ott and Daniel S. Sundheim are Executive Committee members of certain management entities, including Viking Global Investors LP ("VGI"), Viking Global Performance LLC ("VGP") and Viking Long Fund GP LLC ("VLFGP"). VGI provides managerial services to various investment funds, including Viking Global Equities LP ("VGE"), Viking Global Equities II LP ("VGE II") and VGE III Portfolio Ltd. ("VGE III"). VGP is the general partner of VGE and VGE II and the investment manager of VGE III. VLFGP serves as the investment manager of Viking Long Fund Master Ltd. ("VLFM" and, together with VGE, VGE II and VGE III, the "Viking Funds" and the Viking Funds together with VGP and VLFGP, the "Reporting Persons"). Each of the Reporting Persons may be deemed to beneficially own the shares reported on this form. VGI and Messrs. Halvorsen, Ott and Sundheim filed a Form 3 in respect of the Issuer on February 2, 2016.

2. VGI provides managerial services to (i) VGE, which directly holds 256,986 shares of common stock of the Issuer ("Common Stock"); (ii) VGE II, which directly holds 15,072 shares of Common Stock; (iii) VGE III, which directly holds 481,567 shares of Common Stock; and (iv) VLFM, which directly holds 266,782 shares of Common Stock. Because of the relationship between VGI and VGE, VGE II, VGE III and VLFM, VGI may be deemed to beneficially own the shares of Common Stock directly held by VGE, VGE II, VGE III and VLFM.

3. VGP is the general partner of VGE and VGE II and the investment manager of VGE III. Because of the relationships between VGP and VGE, VGE II and VGE III, respectively, VGP may be deemed to beneficially own the shares of Common Stock directly held by VGE, VGE II and VGE III.

4. VLFGP serves as the investment manager of VLFM. Because of the relationship between VLFGP and VLFM, VLFGP may be deemed to beneficially own the shares of Common Stock directly held by VLFM.

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.

6. On February 8, 2016, the Viking Funds acquired an aggregate of 1,000,000 shares of Common Stock at a price of $16.00 per share in connection with the Issuer's initial public offering ("IPO"). VGE acquired 256,986 shares in the IPO, VGE III acquired 481,567 shares in the IPO and VLFM acquired 261,447 shares in the IPO.

7. On February 8, 2016, the Viking Funds acquired an aggregate of 20,407 shares of Common Stock at a purchase price of $18.00 per share in open-market transactions following the IPO. VGE II acquired 15,072 of such shares and VLFM acquired 5,335 of such shares.

Remarks:

(8) The Reporting Persons are jointly filing this Form 3 pursuant to Rule 16a-3(j) under the Exchange Act. (9) Each of O. Andreas Halvorsen, David C. Ott and Daniel S. Sundheim is signing as an Executive Committee Member of VIKING GLOBAL PERFORMANCE LLC, on behalf of itself and VIKING GLOBAL EQUITIES LP, VIKING GLOBAL EQUITIES II LP and VGE III PORTFOLIO LTD., and as an Executive Committee Member of VIKING LONG FUND GP LLC, on behalf of itself and VIKING LONG FUND MASTER LTD.

	/s/ O. Andreas Halvorsen (8)(9)	02/08/2016
	/s/ David C. Ott (8)(9)	02/08/2016
	/s/ Daniel S. Sundheim (8)(9)	02/08/2016
	** Signature of Reporting Person	Date
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