X0306 4 2021-04-13 0 0001403752 Zymeworks Inc. ZYME 0001843630 Priour James C/O ZYMEWORKS INC. 1385 WEST 8TH AVENUE, SUITE 540 VANCOUVER A1 V6H 3V9 BRITISH COLUMBIA, CANADA 0 1 0 0 Chief Commercial Officer Common Shares 2021-04-13 4 M 0 2266 0.00 A 2953 D Common Shares 2021-04-13 4 S 0 950 27.9296 D 2003 D Restricted Stock Unit 2021-04-13 4 M 0 2266 0.00 D Common Shares 2266 4534 D Represents common shares issued upon vesting of one third of the restricted stock units ("RSUs") granted on April 13, 2020. Represents common shares sold to cover tax withholding obligations and other applicable fees in connection with the vesting of RSUs. Pursuant to the terms of the applicable RSU grant agreement (the "Grant Agreement"), effective on the grant date of the RSUs, the Reporting Person irrevocably adopted a 10b5-1 plan pursuant to which the Reporting Person elected to sell shares to cover tax withholding obligations and other applicable fees in accordance with the terms of the Grant Agreement. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $27.92 to $27.96, 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 April 13, 2020 and vest in three equal annual instalments beginning on April 13, 2021. /s/ Daniel Dex, Attorney-in-Fact 2021-04-13