X0306 4 2021-07-12 0 0001403752 Zymeworks Inc. ZYME 0001761853 Tehrani Ali C/O ZYMEWORKS INC. 1385 WEST 8TH AVENUE, SUITE 540 VANCOUVER A1 V6H 3V9 BRITISH COLUMBIA, CANADA 1 1 0 0 Chief Executive Officer Common Shares 2021-07-12 4 M 0 12669 4.3062 A 272994 D Common Shares 2021-07-12 4 S 0 12669 36.1224 D 260325 D Common Shares 55511 I Held by spouse Stock Option (Right to Buy) 4.3062 2021-07-12 4 M 0 12669 0.00 D 2013-01-01 2022-01-01 Common Shares 12669 44991 D Pursuant to a 10b5-1 plan entered into May 13, 2021. The exercise price of the stock option is CAD5.37. The U.S. dollar equivalent of the exercise price is $4.3062 using the Bank of Canada exchange rate for July 12, 2021 (CAD1.00 = $0.8019). The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $36.0649 to $36.5902, inclusive. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on July 12, 2021 at each separate price. Stock options vest as follows: (i) 25% of underlying shares on first anniversary of grant date of January 1, 2012 and (ii) remainder of underlying shares in 36 equal monthly installments on the last day of month following first anniversary of grant date. /s/ Daniel Dex, Attorney-in-Fact 2021-07-13