Vaughn B. Himes - 14 Dec 2023 Form 4 Insider Report for Seagen Inc.

Footnote F1

Reflects the disposition of shares of common stock, par value $0.001 per share ("Common Stock"), of Seagen Inc. ("Issuer"), or of equity awards in respect of such Common Stock, as applicable, in connection with the consummation of the transactions contemplated by the Agreement and Plan of Merger, dated as of March 12, 2023 (the "Merger Agreement"), by and among the Issuer, Pfizer Inc. ("Parent") and Aris Merger Sub, Inc. ("Merger Sub"), a wholly owned subsidiary of Parent, pursuant to which, at 12:01 a.m. EST on December 14, 2023, the effective time of the Merger (the "Effective Time"), Merger Sub merged with and into the Issuer, with the Issuer surviving as a subsidiary of Parent (the "Merger").

Footnote F2

Pursuant to the Merger Agreement, at the Effective Time, each issued and outstanding share of Common Stock (other than certain excluded shares described in the Merger Agreement) was cancelled and converted automatically into the right to receive cash in an amount equal to $229.00 per share of Common Stock (the "Merger Consideration").

Footnote F3

Pursuant to the Merger Agreement, each outstanding option, whether or not then vested, was cancelled in exchange for the right to receive an amount in cash equal to the product of (i) the excess, if any, of the Merger Consideration over the per-share exercise price of such option, multiplied by (ii) the number of shares of Common Stock then subject to such option.

Footnote F4

Pursuant to the Merger Agreement, at the Effective Time, each outstanding restricted stock unit (each, a "Company RSU"), other than any Post-Signing Company RSU (as defined below), was cancelled and converted into the right to receive an amount in cash equal to the product of (i) the Merger Consideration, multiplied by (ii) the number of shares of Common Stock then subject to such Company RSU.

Footnote F5

Pursuant to the Merger Agreement, at the Effective Time, each outstanding Company RSU granted after March 12, 2023 that was unvested as of immediately prior to the Effective Time (each, a "Post-Signing Company RSU") was cancelled and converted into the right to receive a Parent cash-based award subject to service-based vesting requirements with respect to an amount in cash equal to the product of (i) the Merger Consideration, multiplied by (ii) the number of shares of Common Stock then subject to such Post-Signing Company RSU.

Footnote F6

Pursuant to the Merger Agreement, at the Effective Time, each outstanding performance-based restricted stock unit (each, a "Company PSU"), other than any Company Products PSU or any Company August 2023 PSU (each, as defined below), was cancelled and converted into the right to receive cash equal to the product of (i) the Merger Consideration, multiplied by (ii) the number of shares of Common Stock then subject to such Company PSU, based on the greater of the target and actual performance. Amounts are shown here based on actual performance.

Footnote F7

Pursuant to the Merger Agreement, at the Effective Time, each outstanding "Company Products PSU" (as defined in the Merger Agreement) that was unvested as of immediately prior to the Effective Time was cancelled and converted into the right to receive a Parent cash-based award subject to the same performance-based vesting requirements with respect to an amount in cash that is equal to the product of (i) the Merger Consideration, multiplied by (ii) the number of shares of Common Stock then subject to such Company Products PSU.

Footnote F8

Pursuant to the Merger Agreement, at the Effective Time, each outstanding performance-based restricted stock unit granted in August 2023 (each, a "Company August 2023 PSU") that was unvested as of immediately prior to the Effective Time, was cancelled and converted into the right to receive a Parent cash-based award with respect to an amount in cash equal to the product of (i) the Merger Consideration, multiplied by (ii) the number of shares of Common Stock then subject to such Company August 2023 PSU, based on target performance.