Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

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 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Cloonan Michael 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 BLUEBIRD BIO, INC., 455 GRAND UNION BOULEVARD 3. Date of Earliest Transaction (Month/Day/Year) 06/02/2025 (Street) SOMERVILLE, MA 02145 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 06/02/2025 D 1,867 D (1)(2)(3)(4) 0 D

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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

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Cloonan Michael C/O BLUEBIRD BIO, INC. 455 GRAND UNION BOULEVARD SOMERVILLE, MA 02145	X

Signatures

/s/ Michael Cloonan		06/03/2025
**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)	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.

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