X0306 4 2022-01-07 0 0001060736 Seagen Inc. SGEN 0001167496 SIEGALL CLAY B 21823 30TH DRIVE SE BOTHELL WA 98021 1 1 0 0 President & CEO Common Stock 2022-01-07 4 M 0 1100 26.1 A 669045 D Common Stock 2022-01-07 4 S 0 1100 147.16 D 667945 D Common Stock 2022-01-07 4 M 0 3221 26.1 A 671166 D Common Stock 2022-01-07 4 S 0 3221 145.84 D 667945 D Common Stock 2022-01-07 4 M 0 4560 26.1 A 672505 D Common Stock 2022-01-07 4 S 0 4560 144.82 D 667945 D Common Stock 2022-01-07 4 M 0 8163 26.1 A 676108 D Common Stock 2022-01-07 4 S 0 8163 143.91 D 667945 D Non-Qualified Stock Option (right to buy) 26.1 2022-01-07 4 M 0 1100 0.0 D 2022-08-20 Common Stock 1100 135245 D Non-Qualified Stock Option (right to buy) 26.1 2022-01-07 4 M 0 3221 0.0 D 2022-08-20 Common Stock 3221 132024 D Non-Qualified Stock Option (right to buy) 26.1 2022-01-07 4 M 0 4560 0.0 D 2022-08-20 Common Stock 4560 127464 D Non-Qualified Stock Option (right to buy) 26.1 2022-01-07 4 M 0 8163 0.0 D 2022-08-20 Common Stock 8163 119301 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 Rule 10b5-1 trading plan. Reflects sales of common stock executed in multiple transactions at prices ranging from $146.71 to $147.68. 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 $145.42 to $146.38. 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 $144.41 to $145.36. 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 $143.41 to $144.38. 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 at a rate of 25% on 8/20/13 and monthly thereafter until all the options were fully vested on 8/20/16. By: /s/ Jennifer Prosba For: Clay B. Siegall 2022-01-11