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 * Glickman Sarah JS 2. Issuer Name and Ticker or Trading Symbol 2seventy bio, Inc. [TSVT] 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) 2SEVENTY BIO, INC., 60 BINNEY STREET 3. Date of Earliest Transaction (Month/Day/Year) 05/13/2025 (Street) CAMBRIDGE, MA 02142 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 05/13/2025 D(1) 12,050 D (2) 15,602 D Common Stock 05/13/2025 U(1) 15,602 D (3) 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

Stock Options (Right to buy)

$3.93

05/13/2025

D(4)

24,100

(4)

(4)

Common Stock

24,100

(4)

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Glickman Sarah JS 2SEVENTY BIO, INC. 60 BINNEY STREET CAMBRIDGE, MA 02142	X

Signatures

/s/ William Baird, Attorney-in-Fact		05/15/2025
**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)	This Form 4 reports securities disposed pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of March 10, 2025, by and among the Issuer, Bristol-Myers Squibb Company ("Parent"), and Daybreak Merger Sub Inc., a wholly owned subsidiary of Parent ("Merger Sub"). Pursuant to the Merger Agreement, Merger Sub completed a cash tender offer to acquire all of the issued and outstanding shares of common stock of the Issuer, par value $0.0001 per share (the "Company Common Stock"), for a price per share of $5.00 (the "Merger Consideration"), without interest and subject to any withholding of taxes required by applicable law. Effective as of May 13, 2025, Merger Sub merged with and into the Issuer, with the Issuer continuing as the surviving corporation and as a wholly owned subsidiary of Parent (the "Merger").
(2)	Pursuant to the terms of the Merger Agreement, each share of Company Common Stock subject to issuance pursuant to outstanding restricted stock units (each, a "Company RSU Award"), whether vested or unvested that was outstanding immediately prior to the effective time of the Merger (the "Effective Time"), became fully vested, and was cancelled and automatically converted into the right to receive, for each share of Company Common Stock underlying such Company RSU Award, an amount (without interest and subject to deduction for any required withholding under applicable law relating to tax) in cash equal to the Merger Consideration.
(3)	Pursuant to the terms of the Merger Agreement, at the Effective Time, each share of Company Common Stock held by the Reporting Person was tendered in exchange for the Merger Consideration, without interest and subject to any withholding of taxes required by applicable law.
(4)	Pursuant to the terms of the Merger Agreement, each outstanding option to purchase shares of Company Common Stock ("Company Option"), whether vested or unvested, that was outstanding immediately prior to the Effective Time and had a per share exercise price that was less than the Merger Consideration became fully vested, was cancelled and automatically converted into the right to receive for each share of Company Common Stock underlying such Company Option, an amount (without interest and subject to deduction for any required withholding under applicable law) in cash equal to the excess of the Merger Consideration over the per share exercise price of such Company Option. Each Company Option, whether vested or unvested, that was outstanding and unexercised immediately prior to the Effective Time and had a per share exercise price that is equal to or greater than the Merger Consideration was automatically cancelled for no consideration.

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