#1 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").

#2 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").