| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Burow Kristina | Director | C/O METSERA, INC. 3 WORLD TRADE CENTER, 175 GREENWICH STREET, NEW YORK | /s/ Matthew Lang, Attorney-in-Fact for Kristina M. Burow. | 2025-11-13 | 0001569248 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | MTSR | Common Stock | Disposed to Issuer | -2.69K | -100% | 0 | Nov 13, 2025 | Direct | F1, F2, F5 | ||
| transaction | MTSR | Common Stock | Disposed to Issuer | -17.1M | -100% | 0 | Nov 13, 2025 | See footnote | F1, F2, F8 | ||
| transaction | MTSR | Common Stock | Disposed to Issuer | -18.5M | -100% | 0 | Nov 13, 2025 | See footnote | F1, F2, F8 | ||
| transaction | MTSR | Common Stock | Disposed to Issuer | -7.52M | -100% | 0 | Nov 13, 2025 | See footnote | F1, F2, F9 | ||
| transaction | MTSR | Common Stock | Disposed to Issuer | -8.31M | -100% | 0 | Nov 13, 2025 | See footnote | F1, F2, F9 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Underlying Class | Amount | Exercise Price | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | MTSR | Restricted Stock Unit | Award | +2.69K | 2.69K | Nov 13, 2025 | Common Stock | 2.69K | $0.00 | Direct | F5 | |||
| transaction | MTSR | Stock Option (right to buy) | Disposed to Issuer | -16.1K | -100% | 0 | Nov 13, 2025 | Common Stock | 16.1K | $29.25 | Direct | F3, F4, F6 | ||
| transaction | MTSR | Stock Option (right to buy) | Disposed to Issuer | -149K | -100% | 0 | Nov 13, 2025 | Common Stock | 149K | $8.18 | Direct | F3, F4, F7 |
Kristina Burow is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may continue.
| Id | Content |
|---|---|
| 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"), net of all applicable withholding taxes, plus |
| F2 | (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"). |
| F3 | 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, |
| F4 | (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. |
| F5 | 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. There is no vesting applicable to the cash payment and the CVRs. |
| F6 | This option provided for vesting in 12 substantially equal monthly installments from May 20, 2025. |
| F7 | This option provided for vesting in 36 substantially equal monthly installments from November 12, 2024. |
| F8 | Represents shares of Common Stock held directly by ARCH Venture Fund XII, L.P ("ARCH Venture Fund XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP"), as the sole general partner of ARCH Venture Fund XII, may be deemed to beneficially own the shares held by ARCH Venture Fund XII. ARCH Venture Partners XII, LLC ("AVP XII LLC"), as the sole general partner of AVP XII LP, may be deemed to beneficially own the shares held by ARCH Venture Fund XII. AVP XII LP and AVP XII LLC disclaim beneficial ownership except to the extent of any pecuniary interest therein. As members of the investment committee of AVP XII LLC, each of Kristina M. Burow, Keith Crandell, Steven Gillis and Robert Nelsen (the "AVP XII Committee Members") may also be deemed to share the power to direct the disposition and vote of the ARCH Venture Fund XII shares. Each AVP XII Committee Member disclaims beneficial ownership except to the extent of any pecuniary interest therein. |
| F9 | Represents shares of Common Stock held directly by ARCH Venture Fund XIII, L.P.("ARCH Venture Fund XIII"). ARCH Venture Partners XIII, L.P. ("AVP XIII LP"), as the sole general partner of ARCH Venture Fund XIII, may be deemed to beneficially own the shares held by ARCH Venture Fund XIII. ARCH Venture Partners XIII, LLC ("AVP XIII LLC"), as the sole general partner of AVP XIII LP, may be deemed to beneficially own the shares held by ARCH Venture Fund XIII. AVP XIII LP and AVP XIII LLC disclaim beneficial ownership except to the extent of any pecuniary interest therein. As members of the investment committee of AVP XIII LLC, each of Paul L. Berns, Kristina M. Burow, Keith Crandell, Steven Gillis and Robert Nelsen (the "AVP XIII Committee Members") may also be deemed to share the power to direct the disposition and vote of the ARCH Venture Fund XIII shares. Each AVP XIII Committee Member disclaims beneficial ownership except to the extent of any pecuniary interest therein. |