[Form 4] Metsera, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Metsera, Inc. (MTSR): Insider ownership reallocation and small sale reported. A reporting person and affiliated entities recorded multiple “J” code transactions on 11/03/2025, which the filing explains were distributions without payment of consideration. These moved shares among related entities and did not reflect purchase or sale prices.

The filing also shows a small open-market sale: 193 shares at $61.2281 by Impresa Fund IV LLC. Following the transactions, indirect beneficial holdings include 3,091,172 shares “held by persons and entities whose shares are subject to reporting by the undersigned,” 47,843 shares held by F‑Prime Capital Partners Life Sciences Advisors Fund VIII LP, and 3,010 shares held by F‑Prime Inc.

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

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

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^*

FMR LLC

(Last) (First) (Middle)

245 SUMMER STREET

(Street)

BOSTON MA 02210

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Metsera, Inc. [ MTSR ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)	X	Other (specify below)
			See Remark 1

3. Date of Earliest Transaction (Month/Day/Year)
11/03/2025

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/03/2025		J		3,189,540	D	$0(1)	0	I	F-Prime Capital Partners Life Sciences Fund VIII LP
Common Stock	11/03/2025		J		47,843	A	$0(1)	47,843	I	F-Prime Capital Partners Life Sciences Advisors Fund VIII LP
Common Stock	11/03/2025		J		47,843	D	$0(1)	0	I	F-Prime Capital Partners Life Sciences Advisors Fund VIII LP
Common Stock	11/03/2025		J		2,115	A	$0(1)	3,010	I	F-Prime Inc.
Common Stock	11/03/2025		J		2,356,274	A	$0(1)	2,356,274	I	Impresa Fund IV LLC
Common Stock	11/03/2025		S		193	D	$61.2281	2,356,081	I	Impresa Fund IV LLC
Common Stock	11/03/2025		J		2,356,081	D	$0(1)	0	I	Impresa Fund IV LLC
Common Stock	11/03/2025		J		2,617,340	A	$0(1)	3,091,172	I	Shares held by persons and entities whose shares are subject to reporting by the undersigned.

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These holdings were acquired or disposed of (as applicable) in the form of a distribution without payment of consideration.

Remarks:

Remark 1: Abigail P. Johnson is a Director, the Chairman and the Chief Executive Officer of FMR LLC. Members of the Johnson family, including Abigail P. Johnson, are the predominant owners, directly or through trusts, of Series B voting common shares of FMR LLC, representing 49% of the voting power of FMR LLC. The Johnson family group and all other Series B shareholders have entered into a shareholders' voting agreement under which all Series B voting common shares will be voted in accordance with the majority vote of Series B voting common shares. Accordingly, through their ownership of voting common shares and the execution of the shareholders' voting agreement, members of the Johnson family may be deemed, under the Investment Company Act of 1940, to form a controlling group with respect to FMR LLC. The address of Abigail P. Johnson is c/o FMR LLC, 245 Summer Street, Boston, MA 02110. Remark 2: The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the undersigned are the beneficial owners of any securities reported herein. Remark 3: F-Prime Capital Partners Life Sciences Advisors Fund VIII LP (FPCPLSA) is the general partner of F-Prime Capital Partners Life Sciences Fund VIII LP. FPCPLSA is solely managed by Impresa Management LLC, the managing member of its general partner and its investment manager. Impresa Fund IV LLC is solely managed by Impresa Management LLC, its general partner and investment manager. Impresa Management LLC is owned, directly or indirectly, by various shareholders and employees of FMR LLC, including certain members of the Johnson family. F-Prime Inc. is a wholly-owned subsidiary of FMR LLC.

	/s/ Stephanie J. Brown, Duly authorized under Powers of Attorney, by and on behalf of FMR LLC and its direct and indirect subsidiaries, and Abigail P. Johnson	11/05/2025
	** 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.

FAQ

What did MTSR’s latest Form 4 report on 11/03/2025?

It reported multiple “J” code distributions without consideration among affiliated entities and a sale of 193 shares at $61.2281.

How many MTSR shares were sold and at what price?

Impresa Fund IV LLC sold 193 shares at $61.2281.

Were most MTSR transactions purchases or sales?

Most were “J” code distributions, which the filing states occurred without payment of consideration.

What are the indirect MTSR holdings after the transactions?

Indirect holdings include 3,091,172 shares held across reportable entities, 47,843 shares at F‑Prime Capital Partners Life Sciences Advisors Fund VIII LP, and 3,010 shares at F‑Prime Inc.

Did the Form 4 indicate a trading plan under Rule 10b5-1?

The form includes the standard 10b5-1 checkbox text; the excerpt does not state that it was checked.

What does transaction code “J” mean for MTSR in this filing?

The filing explains these holdings were acquired or disposed of as a distribution without payment of consideration.