[Form 4] Metsera, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Metsera (MTSR) filed a Form 4 reflecting transactions tied to its merger with Pfizer. At closing, each share of Metsera common stock converted into the right to receive $65.60 in cash per share plus one contingent value right (CVR), per the merger terms.

The reporting person recorded an acquisition of 2,688 RSUs on November 12, 2025, which were then canceled and converted into cash at the Closing Amount and an equal number of CVRs. Outstanding stock options were canceled in exchange for cash equal to intrinsic value and one CVR per underlying share; unvested awards follow prior schedules with vesting on the first merger anniversary subject to continued service. Following these transactions, the Form 4 shows 0 shares of common stock beneficially owned.

Insights

M&A and Equity Compensation Analyst

Form 4 documents merger consideration and equity award treatment.

The filing records how Metsera equity converted at closing: each common share became the right to receive $65.60 in cash plus one CVR. This is standard for an all-cash deal with an added contingent instrument. The Form 4 aligns insider holdings to the closing mechanics.

RSUs (2,688 units) were canceled and converted into cash at the Closing Amount and CVRs on a one-for-one basis. Options were canceled for cash equal to intrinsic value (Closing Amount minus exercise price) and one CVR per underlying share; unvested pieces keep their schedules with vesting on the first anniversary, contingent on continued service.

For investors, this is administrative but confirms consideration terms and award handling. Actual outcomes for CVRs depend on milestone achievements disclosed elsewhere.

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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X

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^*

Pinto Joshua

(Last) (First) (Middle)

C/O METSERA, INC. 3 WORLD TRADE

CENTER 175 GREENWICH STREET

(Street)

NEW YORK NY 10007

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
11/13/2025

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	11/13/2025		D(1)(2)		2,688	D	(1)(2)(5)	0	D

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
Restricted Stock Unit	$0	11/13/2025		A		2,688		(5)	(5)	Common Stock	2,688	(5)	2,688	D
Stock Option (right to buy)(3)(4)	$29.25	11/13/2025		D			16,125	(6)	05/19/2035	Common Stock	16,125	(3)(4)	0	D
Stock Option (right to buy)(3)(4)	$4.33	11/13/2025		D			148,953	(7)	09/26/2034	Common Stock	148,953	(3)(4)	0	I	By LLC(8)

Explanation of Responses:

1. 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"), net of all applicable withholding taxes, plus (ii) one contractual contingent value right representing the right to receive contingent payments (a "CVR") in cash,

2. (Continued from footnote 1) 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").

3. Pursuant to the Merger Agreement, each outstanding and unexercised option immediately prior to the Effective Time, whether vested or unvested, was cancelled in exchange for the right to receive (x) an amount in cash equal to the product of (i) the excess, if any, of the Closing Amount minus the exercise price of such option, multiplied by (ii) the number of shares of Common Stock subject to such option immediately prior to the Effective Time, net of all applicable withholding taxes, and (y) one CVR for each share of the Common Stock subject to such stock option immediately prior to the Effective Time. In the case of any unvested stock options,

4. (Continued from footnote 3) the cash payment and the CVRs are subject to the same vesting schedule terms as were applicable to the stock options, except that all such payments will become vested upon the first anniversary of the closing of the Merger, subject to the holder's continued service with the Parent or its subsidiaries through the first anniversary of the Merger.

5. On November 12, 2025, the Reporting Person was granted restricted stock units ("RSUs") under the Company's 2025 Incentive Award Plan in a transaction exempt under Rule 16b-3. Each RSU represents a contingent right to receive one share of Common Stock. The RSUs vest in 36 substantially equal monthly installments from November 12, 2025. Pursuant to the Merger Agreement, all RSUs were cancelled and converted into the right to receive (x) an amount of cash equal to the Closing Amount multiplied by the number of shares of Common Stock subject to such RSU immediately prior to the Effective Time, net of all applicable withholding taxes, and (y) a number of CVRs equal to the under of the shares of Common Stock underlying the RSU. The cash payment and the CVRs are not subject to vesting.

6. This option provided for vesting in 12 substantially equal monthly installments from May 20, 2025.

7. This option provided for vesting in 36 substantially equal monthly installments from September 27, 2024.

8. Reflects securities held by Maple DE Holdings LLC (the "LLC"). The units of the LLC are held by a trust for which the Reporting Person exercises investment control and is a beneficiary.

	/s/ Matthew Lang, Attorney-in-Fact for Joshua Pinto	11/13/2025
	** Signature of Reporting Person	Date
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