X0407 4 2023-04-10 0 0001060736 Seagen Inc. SGEN 0001216477 SIMPSON TODD E 21823 30TH DRIVE SE BOTHELL WA 98021 0 1 0 0 Chief Financial Officer 1 Common Stock 2023-04-10 4 M 0 14980 46.37 A 133926 D Common Stock 2023-04-10 4 S 0 14980 204.14 D 118946 D Common Stock 2023-04-10 4 M 0 40364 46.37 A 159310 D Common Stock 2023-04-10 4 S 0 40364 204.74 D 118946 D Non-Qualified Stock Option (right to buy) 46.37 2023-04-10 4 M 0 14980 0.00 D 2027-08-17 Common Stock 14980 40364 D Non-Qualified Stock Option (right to buy) 46.37 2023-04-10 4 M 0 40364 0.00 D 2027-08-17 Common Stock 40364 0 D Amount of securities beneficially owned following reported transactions includes restricted stock units subject to vesting. The sales reported in this Form 4 were effected pursuant to a written plan adopted on December 9, 2022 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). Reflects sales of common stock executed in multiple transactions at prices ranging from $203.49 to $204.48. The price reported reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request by the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the sales were effected. Reflects sales of common stock executed in multiple transactions at prices ranging from $204.49 to $205.00. The price reported reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request by the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the sales were effected. Options vested 25% on 8/17/18 and monthly thereafter until all the options were fully vested on 8/17/21. By: /s/ Jennifer Prosba For: Todd E. Simpson 2023-04-12