[Form 4] Metsera, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Metsera (MTSR) CFO filed a Form 4 detailing equity conversion and cancellation tied to the Pfizer merger. At closing, each Metsera common share was converted into the right to receive $65.60 in cash per share plus one contingent value right (CVR), as described in the merger terms.

The filing shows disposition of 21,250 shares of common stock, leaving 0 shares beneficially owned after the transaction. It also records the award and conversion of 21,250 RSUs, which became the right to receive cash based on $65.60 per underlying share and an equal number of CVRs, subject to the original vesting schedule. All stock options were canceled in exchange for cash equal to any in-the-money value plus one CVR per underlying share, including grants for 150,000 options at $29.25, 255,349 at $4.33, and 340,465 at $8.18, each with 0 remaining after the merger mechanics.

Insights

Equity compensation & M&A analyst

Form 4 reflects merger consideration mechanics for insider equity.

The filing documents how Metsera equity converted at closing: each common share into $65.60 cash plus one CVR, with all RSUs and options canceled and replaced by cash and CVRs per underlying shares. This is standard treatment where vested and unvested awards follow defined merger terms.

For options, cash equals any intrinsic value ($65.60 minus exercise price) times shares, plus a CVR per share; RSUs receive cash at $65.60 per unit plus a CVR per unit. Some unvested awards keep vesting terms with a vesting acceleration on the first anniversary of closing, conditioned on continued service.

Impact is administrative for public holders: insider holdings go to zero post-closing, and future value, if any, depends on CVR milestone outcomes disclosed by the acquirer. No ongoing ownership by the reporting person is shown after these conversions.

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
Estimated average burden
hours per response:			0.5

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^*

Visioli Christopher

(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)

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

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)		21,250	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		21,250		(5)	(5)	Common Stock	21,250	(5)	21,250	D
Stock Option (right to buy)(3)(4)	$29.25	11/13/2025		D			150,000	(6)	05/19/2035	Common Stock	150,000	(3)(4)	0	D
Stock Option (right to buy)(3)(4)	$4.33	11/13/2025		D			255,349	(7)	09/26/2034	Common Stock	255,349	(3)(4)	0	D
Stock Option (right to buy)(3)(4)	$8.18	11/13/2025		D			340,465	(8)	11/11/2034	Common Stock	340,465	(3)(4)	0	D

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

2. (Continued from footnote 1) (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").

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, the cash payment and the CVRs are subject to the same vesting schedule terms as were applicable to the stock options,

4. (Continued from footnote 3) 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 subject to the same vesting schedule terms as were applicable to the RSUs.

6. This option provided for vesting in 48 substantially equal monthly installments from May 20, 2025.

7. This option provided for vesting in 48 substantially equal monthly installments from September 27, 2024.

8. This option provided for vesting in 48 substantially equal monthly installments from October 28, 2024.

	/s/ Matthew Lang, as Attorney-in-Fact for Christopher Visioli	11/13/2025
	** 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 Metsera (MTSR) shareholders receive in the merger?

Each share converted into the right to receive $65.60 in cash plus one CVR per share.

What happened to the CFO’s Metsera common shares?

The filing shows a disposition of 21,250 common shares, with 0 shares beneficially owned after the transaction.

How were Metsera (MTSR) RSUs treated at closing?

Each RSU became the right to receive cash equal to $65.60 per unit and one CVR per unit, following the original vesting schedule.

How were stock options handled in the Metsera-Pfizer merger?

Options were canceled for cash equal to intrinsic value plus one CVR per underlying share; remaining counts went to 0.

What specific option grants were canceled for the CFO?

Grants included 150,000 at $29.25, 255,349 at $4.33, and 340,465 at $8.18, all reduced to 0 post-closing.

Do unvested awards keep vesting after the merger?

Yes. Unvested cash and CVR replacement payments remain on the prior schedule and vest on the first anniversary subject to continued service.