SEC FORM 4

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).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Casdin Capital, LLC

(Last)

(First)

(Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
05/13/2025

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

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

	Form filed by One Reporting Person
X	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, par value $0.0001 per share	05/13/2025		U⁽¹⁾⁽²⁾		22,625	D	$5⁽¹⁾⁽²⁾	0	D⁽³⁾
Common Stock, par value $0.0001 per share	05/13/2025		U⁽¹⁾⁽²⁾		2,000,000	D	$5⁽¹⁾⁽²⁾	0	I	See footnote⁽⁴⁾

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)
Stock Options (Right to buy)	$3.93	05/13/2025		D			12,050⁽⁵⁾	⁽⁵⁾	⁽⁵⁾	Common Stock, par value $0.0001 per share	12,050	⁽⁵⁾	0	D⁽³⁾
Stock Options (Right to buy)	$4.54	05/13/2025		D			33,400⁽⁵⁾	⁽⁵⁾	⁽⁵⁾	Common Stock, par value $0.0001 per share	33,400	⁽⁵⁾	0	D⁽³⁾

1. Name and Address of Reporting Person^*

Casdin Capital, LLC

(Last)

(First)

(Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Eli

(Last)

(First)

(Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Partners Master Fund, L.P.

(Last)

(First)

(Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Partners GP, LLC

(Last)

(First)

(Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. Represents securities that were tendered in connection with the Agreement and Plan of Merger (the "Merger Agreement"), dated March 10, 2025, by and among 2seventy bio, Inc. (the "Company"), Daybreak Merger Sub Inc. ("Merger Sub") and Bristol-Myers Squibb Company ("Parent"). Following completion of a cash tender offer by Merger Sub to acquire all of the issued and outstanding shares of the Company's common stock, par value $0.0001 per share (the "Company Common Stock") for $5.00 per share (the "Merger Consideration"), Merger Sub merged with and into the Company, with the Company continuing as the surviving corporation and a whole owned subsidiary of Parent (the "Merger").

2. cont'd from footnote (1): Each restricted stock unit in respect of Company Common Stock ("Company RSU Award"), whether vested or unvested, that was outstanding immediately prior to the effective time of the Merger (the "Effective Time") was fully vested, was cancelled and automatically converted into the right to receive, for each share of Company Common Stock underlying such Company RSU Award immediately prior to the Effective Time, 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. Additionally, effective as of the Effective Time and as a result of the Merger, Eli Casdin ceased to be a member of the Company's board of directors.

3. The securities were owned directly by Eli Casdin.

4. The securities were owned directly by Casdin Partners Master Fund, L.P. (the "Master Fund") and may be deemed to have been indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to the Master Fund ("Casdin"), (ii) Casdin Partners GP, LLC, the general partner of the Master Fund (the "GP"), and (iii) Eli Casdin, the managing member of Casdin and the GP.

5. Each option to purchase Company Common Stock ("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 was less than the Merger Consideration was fully vested, was cancelled and automatically converted into the right to receive, for each share of Company Common Stock underlying such Company Option immediately prior to the Effective Time, an amount (without interest and subject to deduction for any required withholding under applicable law relating to tax) in cash equal to the excess of the Merger Consideration over the per share exercise price of such Company Option.

Remarks:

Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

	Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member	05/15/2025
	/s/ Eli Casdin, Eli Casdin	05/15/2025
	Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member	05/15/2025
	Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member	05/15/2025
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

SEC Form 4 filed by Director Casdin Capital, Llc