SEC FORM 4

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

TEPPER ROBERT I

(Last)

(First)

(Middle)

C/O THIRD ROCK VENTURES, L.P.

29 NEWBURY STREET

(Street)

BOSTON

02116

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
bluebird bio, Inc. [ BLUE ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
06/24/2013

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	06/24/2013		C		4,734,248⁽¹⁾	A	$0.00	4,734,248	I	See footnote⁽²⁾

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Series B Convertible Preferred Stock	⁽³⁾	06/24/2013		C			64,377,682	⁽³⁾	⁽³⁾	Common Stock	3,394,194	⁽³⁾	0	I	See footnote⁽²⁾
Series C Convertible Preferred Stock	⁽³⁾	06/24/2013		C			14,379,294	⁽³⁾	⁽³⁾	Common Stock	758,121	⁽³⁾	0	I	See footnote⁽²⁾
Series D Convertible Preferred Stock	⁽³⁾	06/24/2013		C			11,037,527	⁽³⁾	⁽³⁾	Common Stock	581,933	⁽³⁾	0	I	See footnote⁽²⁾

Explanation of Responses:

1. Represents the total number of shares received upon conversion of shares of the Issuer's Series B Convertible Preferred Stock (the "Series B Shares"), Series C Convertible Preferred Stock (the "Series C Shares") and Series D Convertible Preferred Stock (the "Series D Shares" and together with the Series B Shares and the Series C Shares, collectively, the "Preferred Shares").

2. The securities are directly held by Third Rock Ventures, L.P. ("TRV LP"). The general partner of TRV LP is Third Rock Ventures GP, LP ("TRV GP"). The general partner of TRV GP is TRV GP, LLC. The Reporting Person is a manager of TRV GP, LLC and disclaims beneficial ownership of all shares except to the extent of his pecuniary interest, if any, therein.

3. Effective upon the closing of the Issuer's initial public offering of its Common Stock, each Preferred Share automatically converted at a ratio of 18.967-to-one into the number of shares of Commmon Stock shown in column 7. The Preferred Shares had no expiration date.

Remarks:

	/s/ Linda C. Bain, Attorney-in-Fact	06/26/2013
	** 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 4 (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).
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