13D Filings
Metsera, Inc.
Amendment
Ownership

0.00%

Total Shares

0

Issuer CIK

2040807

CUSIP

59267L107

Event Date

Nov 12, 2025

Accepted

Nov 14, 2025, 06:22 PM

Reporting Persons (11)
Joint Filing

This is a joint filing. The reported shares may overlap between reporting persons and should not be summed.

NameType% of ClassAggregateSole VotingShared Voting
ARCH Venture Fund XII, L.P.
Partnership
0.00%000
ARCH Venture Fund XIII, L.P.
Partnership
0.00%000
ARCH Venture Partners XII, L.P.
Partnership
0.00%000
ARCH Venture Partners XIII, L.P.
Partnership
0.00%000
ARCH Venture Partners XII, LLC
Other
0.00%000
ARCH Venture Partners XIII, LLC
Other
0.00%000
Robert Nelsen
Individual
0.00%000
Keith Crandell
Individual
0.00%000
Kristina Burow
Individual
0.00%000
Steven Gillis
Individual
0.00%000
Paul Berns
Individual
0.00%000
Disclosure Items (2)

Security Title

Common Stock, $0.00001 par value

Issuer Name

Metsera, Inc.

Issuer Address

3 World Trade Center, New York, NY, 10007

Percentage of Class

Item 5 of this Schedule 13D is amended and supplemented as follows: Pursuant to the Agreement and Plan of Merger dated September 21, 2025, as amended on November 7, 2025 (the "Merger Agreement"), by and among the Issuer, Pfizer Inc., a Delaware corporation ("Parent"), and Mayfair Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), Merger Sub merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of 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 Isser was converted automatically into the right to receive (i) cash in an amount equal to $65.60 per share without interest, net of all applicable withholding taxes, plus (ii) one contractual contingent value right representing the right to receive contingent payments 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 Parent and Equiniti Trust Company, LLC, dated November 13, 2025.

Number of Shares

Regarding the number of shares as to which such person has: (i) sole power to vote or to direct the vote: See line 7 of cover sheets. (ii) shared power to vote or to direct the vote: See line 8 of cover sheets. (iii) sole power to dispose or to direct the disposition: See line 9 of cover sheets. (iv) shared power to dispose or to direct the disposition: See line 10 of cover sheets.

Transactions

Except as set forth above, none of the Reporting Persons has effected any transaction in the Common Stock during the last 60 days.

Shareholders

No other person is known to have the right to receive or the power to direct the receipt of dividends from, or any proceeds from the sale of, shares beneficially owned by any of the Reporting Persons.

Date of 5% Ownership

On November 13, 2025, as a result of the transactions described in Item 5(a) hereof, the Reporting Persons ceased to be the beficial owners of 5% or more of the Common Stock.