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 ^*

Vittiglio Joseph

(Last)

(First)

(Middle)

C/O BLUEBIRD BIO, INC.

455 GRAND UNION BOULEVARD

(Street)

SOMERVILLE

02145

(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)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
Chief Business & Legal Officer

3. Date of Earliest Transaction (Month/Day/Year)
05/30/2025

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	05/30/2025		U		1,143	D	⁽¹⁾ ⁽²⁾	3,125	D
Common Stock	06/02/2025		D		3,125	D	⁽³⁾ ⁽⁴⁾	0	D
Common Stock	06/02/2025		A		2,500	A	⁽⁵⁾ ⁽⁶⁾	2,500	D
Common Stock	06/02/2025		D		2,500	D	⁽⁵⁾ ⁽⁶⁾	0	D

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)

Explanation of Responses:

1. In connection with the terms of an Agreement and Plan of Merger, dated as of February 21, 2025 (as amended, the "Merger Agreement"), by and among the Issuer, Beacon Parent Holdings, L.P. ("Parent") and Beacon Merger Sub, Inc., an indirect wholly owned subsidiary of Parent ("Purchaser"), Purchaser completed a tender offer for shares of the Issuer's Common Stock. Tendering stockholders were given the option to receive per share consideration of either (x) $3.00 in cash per share, subject to any applicable withholding taxes and without interest thereon, plus one contingent value right ("CVR") per share, representing the right to receive one contingent payment of $6.84, in cash, subject to any applicable withholding taxes and without interest thereon, upon achievement of the specified milestone or (y) $5.00 in cash per share, subject to any applicable withholding taxes and without interest thereon (collectively, the "Offer Price").

2. (Continued from footnote 1) After completion of the tender offer, Purchaser merged with and into the Issuer (the "Merger"), effective as of June 2, 2025 (the "Effective Time"), with the Issuer continuing as the surviving entity and a wholly owned subsidiary of Parent.

3. Pursuant to the terms of the Merger Agreement, immediately prior to the Effective Time, each time-based restricted stock unit award with respect to shares that is, at the time of determination, subject to vesting or forfeiture conditions and that is not a PSU Award (as defined below) (but including, for clarity, any PSU Award that is subject solely to service-based vesting conditions as of the Effective Time) ("RSU Award") that is outstanding as of immediately prior thereto, shall (a) accelerate and become fully vested, and (b) by virtue of the Merger automatically (except as otherwise provided in the Merger Agreement) and without any action on the part of the Issuer, Parent or the holder thereof, be canceled and terminated and converted into the right to receive

4. (Continued from footnote 3) (i) an amount in cash equal to the product of the number of shares underlying such RSU Award immediately prior to the Effective Time and $3.00 in cash, subject to any applicable withholding taxes and without interest thereon plus (ii) one CVR with respect to each share subject to such RSU Award immediately prior to the Effective Time.

5. Pursuant to the terms of the Merger Agreement, immediately prior to the Effective Time, each performance-based restricted stock unit award with respect to shares that is, at the time of determination, subject to performance-based vesting or forfeiture conditions ("PSU Award") that is outstanding and vested as of immediately prior thereto, or which shall become vested as required under the terms governing the PSU Award, shall by virtue of the Merger automatically and (except as otherwise provided in the Merger Agreement) without any action on the part of the Issuer, Parent or the holder thereof, be canceled and terminated and converted into the right to receive

6. (Continued from footnote 5) (i) an amount in cash equal to the product of the number of shares underlying such PSU Award immediately prior to the Effective Time (assuming that the applicable performance goals have been deemed to be achieved at the greater of target and actual level of performance as determined by the Compensation Committee of the Issuer's board of directors in its discretion) and $3.00 in cash, subject to any applicable withholding taxes and without interest thereon plus (ii) one CVR with respect to each such share subject to such PSU Award immediately prior to the Effective Time.

	/s/ Joseph Vittiglio	06/03/2025
	** Signature of Reporting Person	Date
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