X0306 4 2023-03-10 0 0001937653 Zymeworks Inc. ZYME 0001761857 Klompas Neil A C/O ZYMEWORKS INC. 108 PATRIOT DRIVE, SUITE A MIDDLETOWN DE 19709 0 1 0 0 President & COO Common Stock 2023-03-10 4 M 0 2500 0.00 A 17301 D Common Stock 2023-03-10 4 M 0 2708 0.00 A 20009 D Common Stock 2023-03-10 4 S 0 2977 7.8259 D 17032 D Common Stock 700 I Held by spouse Restricted Stock Unit 2023-03-10 4 M 0 2500 0.00 D Common Stock 2500 0 D Restricted Stock Unit 2023-03-10 4 M 0 2708 0.00 D Common Stock 2708 2709 D Represents shares of common stock issued upon vesting of one third of the restricted stock units ("RSUs") granted on March 10, 2020. Represents shares of common stock issued upon vesting of one third of the RSUs granted on March 10, 2021. Represents shares of common stock sold to cover tax withholding obligations and other applicable fees in connection with the vesting of RSUs pursuant to mandatory "sell to cover" provisions contained in the Reporting Person's applicable RSU grant agreement, and does not represent a discretionary sale by the Reporting Person. The Reporting Person did not sell or otherwise dispose of any of the shares reported on this Form 4 for any reason other than to cover required taxes and fees. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $7.815 to $7.86, inclusive. Upon request by the Commission staff, the Issuer, or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price. Each RSU represents the contingent right to receive, upon vesting of the RSU, one share of the Issuer's common stock. The RSUs were granted on March 10, 2020 and vest in three equal annual instalments beginning on March 10, 2021. The RSUs were granted on March 10, 2021 and vest in three equal annual instalments beginning on March 10, 2022. /s/ Daniel Dex, Attorney-in-Fact 2023-03-14