MTSR insider reports merger conversion: $65.60 cash and one CVR

Rhea-AI Filing Summary

Metsera (MTSR) filed a Form 4 reporting transactions tied to its merger with Pfizer. At closing, each Metsera common share was converted into the right to receive $65.60 in cash plus one contingent value right (CVR). Outstanding stock options were canceled for a cash amount based on the in‑the‑money value using the $65.60 price, plus one CVR per underlying share. RSUs were canceled for cash at $65.60 per unit and an equal number of CVRs. Unvested option and RSU payouts continue on their original schedules and become fully vested on the first anniversary of the merger, subject to continued service. Following the transactions, 12,767,462 shares are shown as indirectly beneficially owned through Population Health Partners entities.

Insights

M&A and Equity Compensation Analyst

Merger consideration: $65.60 cash per share plus one CVR.

Metsera completed a merger in which each common share converts into $65.60 cash plus one CVR. Equity awards were cash-settled using the $65.60 reference and granted matching CVRs per underlying share.

Per terms, unvested options and RSUs retain their vesting schedules and accelerate to fully vested on the first anniversary of closing, contingent on continued service. This aligns awardholder outcomes with the merger timeline.

The filing also lists indirect beneficial ownership of 12,767,462 shares through Population Health Partners entities. Subsequent disclosures may detail CVR milestone achievements and any resulting payments.

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^*

Bernard Christopher Whitten

(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
X	Officer (give title below)		Other (specify below)
	See Remarks

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
Common Stock	11/13/2025		D(1)(2)		12,767,462	D	(1)(2)	0	I	Held by Population Health Partners, L.P. and Population Health GP LLC(8)

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			348,750	(6)	05/19/2035	Common Stock	348,750	(3)(4)	0	D
Stock Option (right to buy)(3)(4)	$4.33	11/13/2025		D			1,702,328	(7)	09/26/2034	Common Stock	1,702,328	(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. 12,639,787 Shares of Common Stock are held of record Population Health Partners, L.P. ("PHP LP") and 127,675 shares of Common Stock are held of record by Population Health GP LLC ("PHP GP LLC"). PHP GP LLC, as the sole general partner of PHP LP, may be deemed to beneficially own the shares of Common Stock held by PHP LP (together with the shares of Common Stock held by PHP GP LLC as holder of record, the "PHP Shares"). As a member of PHP GP LLC, the Reporting Person may be deemed to share the power to direct the disposition and vote of the PHP Shares. The Reporting Person disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein, and this report shall not be deemed an admission that it is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

Remarks:

PRESIDENT AND CHIEF EXECUTIVE OFFICER

	/s/ Matthew Lang, Attorney-in-Fact for Christopher Witten Bernard	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 Pfizer merger?

Each share converted into $65.60 in cash plus one CVR representing potential future cash payments upon specified milestones.

How were Metsera stock options treated in the transaction?

Each option was canceled for cash equal to its in-the-money value using $65.60 per share and one CVR per underlying share.

What happened to Metsera RSUs (MTSR) at closing?

RSUs were canceled and converted into $65.60 per unit in cash and an equal number of CVRs, following the original vesting schedule.

Do unvested awards vest immediately after the merger?

Unvested awards keep their schedules and become fully vested on the first anniversary of closing, subject to continued service.

What indirect holdings are reported for the insider?

The filing shows 12,767,462 shares indirectly beneficially owned through Population Health Partners, L.P. and Population Health GP LLC.

When was the CVR agreement dated?

The contingent value rights agreement was dated November 13, 2025.