Edgar Filing: bluebird bio, Inc.

Ownership Submission

FORM 4

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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person ^*

TEPPER ROBERT I

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)

(Last)

(First)

(Middle)

C/O THIRD ROCK VENTURES, L.P., 29 NEWBURY STREET

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

(Street)

BOSTON, MA 02116

4. If Amendment, Date 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

(City)

(State)

(Zip)

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/24/2013		C		4,734,248 ⁽¹⁾	A	$ 0	4,734,248	I	See footnote ⁽²⁾

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities
(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 of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)

11. Nature of Indirect Beneficial Ownership
(Instr. 4)

Code

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Series B Convertible Preferred Stock

⁽³⁾

06/24/2013

64,377,682

⁽³⁾

Common Stock

3,394,194

⁽³⁾

See footnote ⁽²⁾

Series C Convertible Preferred Stock

⁽³⁾

06/24/2013

14,379,294

⁽³⁾

Common Stock

758,121

⁽³⁾

See footnote ⁽²⁾

Series D Convertible Preferred Stock

⁽³⁾

06/24/2013

11,037,527

⁽³⁾

Common Stock

581,933

⁽³⁾

See footnote ⁽²⁾

Reporting Owners

Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
TEPPER ROBERT I C/O THIRD ROCK VENTURES, L.P. 29 NEWBURY STREET BOSTON, MA 02116	X

Signatures

/s/ Linda C. Bain, Attorney-in-Fact		06/26/2013
^**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(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.

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