[Form 4] Metsera, Inc. Insider Trading Activity

Rhea-AI Filing Summary

FMR LLC filed a Form 4 reporting insider changes in Metsera, Inc. (MTSR). On 10/06/2025 a disposition of 633,715 common shares was reported with a price shown as $0.00. After the reported transaction, the filing shows 473,832 shares beneficially owned indirectly. The filing identifies relationships linking Abigail P. Johnson to FMR LLC and notes various indirect holdings through F-Prime entities and funds.

Positive

• Continued disclosure of insider activity by FMR LLC and related parties provides transparency
• Significant indirect holdings remain (e.g., 3,189,540 shares linked to FMR LLC) indicating ongoing ownership interest

Negative

• Large disposition reported of 633,715 shares on 10/06/2025, which could reduce the firm's effective stake if shares left affiliate control
• Transaction price listed as $0.00 lacks clarity, leaving uncertainty about whether the shares were sold, transferred, or reallocated

Insights

Corporate Governance Analyst

Large indirect disposal noted; ownership links to family-controlled entity.

The filing is by FMR LLC, which reports an indirect disposition of 633,715 common shares on 10/06/2025

Abigail P. Johnson is identified as a director and key family owner tied to voting control of FMR LLC; holdings remain indirect at 473,832 shares after the disposal. Watch for any subsequent filings clarifying the $0.00 price line or attributing the transfer to an internal reorganization or affiliate movement within the FMR/F-Prime structure.

Equity Transactions Specialist

Transaction appears non‑cash or affiliate reallocation; material share count moved.

The record shows a reported sale/disposition code with price $0.00, which can indicate a transfer among affiliates or a non‑cash distribution rather than an open‑market sale. The filer lists multiple indirect holdings across FMR and F-Prime entities, including 3,189,540 shares associated with FMR LLC and smaller positions through F-Prime funds.

Investors should note the exact nature of the $0.00 transaction is not specified here; any market impact depends on whether shares re‑entered public float or were moved within controlled entities—monitor further Section 16 filings for clarifying detail within the next reporting window.

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)
10/06/2025

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								3,189,540	I	F-Prime Capital Partners Life Sciences Fund VIII LP
Common Stock								895	I	F-Prime Inc.
Common Stock	10/06/2025		G		633,715	D	$0.00	473,832	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:

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 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	10/08/2025
	** 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 the Form 4 filed for Metsera (MTSR) report?

The Form 4 reports that FMR LLC reported a disposition of 633,715 common shares on 10/06/2025 and shows 473,832 shares beneficially owned following the transaction.

Who is the reporting person on the MTSR Form 4?

The reporting person is FMR LLC; the filing also describes Abigail P. Johnson's role as a director and family ownership links to FMR LLC's voting control.

Does the filing explain why the price is listed as $0.00?

No. The Form 4 shows a price of $0.00 for the disposed shares but does not provide further explanation; this can reflect an affiliate transfer or non‑cash movement.

How many shares remain beneficially owned after the transaction?

The filing reports 473,832 shares beneficially owned following the reported transaction.

Are there other related entities mentioned in the filing?

Yes. The filing references holdings through F-Prime Capital Partners Life Sciences Fund VIII LP and F-Prime Inc., and explains management and ownership links to FMR LLC and the Johnson family.