FMR LLC - 13 Nov 2025 Form 4 Insider Report for Metsera, Inc. (MTSR)

Reporting relationship: Other*, 10%+ Owner
Issuer ticker: MTSR
Reported as of: 13 Nov 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 17 Nov 2025, 13:51:07 UTC
Prior SEC filing: 12 Nov 2025
Next SEC filing: 10 Dec 2025
Source filing: View source filing
Reporting owner signature: /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

Key filing fact

FMR LLC filed Form 4 for Metsera, Inc. (MTSR) on 17 Nov 2025.

Key facts

This page summarizes FMR LLC's Form 4 filing for Metsera, Inc. (MTSR).
2 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 17 Nov 2025, 13:51.

Change

Previous filing in this sequence was filed on 12 Nov 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0000315066 Primary reporting owner

FMR LLC

Relationship: Other*, 10%+ Owner
Address: 245 SUMMER STREET, BOSTON
Signature: /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
Signature date: 17 Nov 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MTSR transaction

Common Stock

Other

Transaction value
Shares: -3,010
Change %: -100%
Price
Shares after: 0
Date: 13 Nov 2025
Ownership: F-Prime Inc.
Footnotes: F1, F2

MTSR transaction

Common Stock

Other

Transaction value
Shares: -2,230,450
Change %: -100%
Price
Shares after: 0
Date: 13 Nov 2025
Ownership: Shares held by persons and entities whose shares are subject to reporting by the undersigned.
Footnotes: F1, F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

FMR LLC is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 2 footnotes

Footnote F1

Pursuant to the Agreement and Plan of Merger dated September 21, 2025, as amended on November 7, 2025 (the "Merger Agreement"), by and among Metsera, Inc. (the "Company"), Pfizer Inc., a Delaware corporation ("Parent"), and Mayfair Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of the Parent (the "Merger Sub"), the Merger Sub merged with and into the Company, with the Company continuing as the surviving corporation and a wholly owned subsidiary of the Parent (the "Merger"). At the Effective Time of the Merger (as defined in the Merger Agreement), each issued and outstanding share of common stock, par value $0.00001 per share of the Company (the "Common Stock") was converted automatically into the right to receive (i) cash in an amount equal to $65.60 per share without interest (the "Closing Amount"),

Footnote F2

(Continued from footnote 1) net of all applicable withholding taxes, plus (ii) one contractual contingent value right representing the right to receive contingent payments (a "CVR") in cash, without interest, upon the achievement of certain specified milestones, in accordance with the terms and conditions of the contingent value rights agreement entered into by the Parent and Equiniti Trust Company, LLC, dated November 13, 2025 (collectively, the "Merger Consideration").

SEC 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 Inc. is a wholly-owned subsidiary of FMR LLC.