144 0001567045 XXXXXXXX LIVE 0001937653 Zymeworks Inc. 001-41535 108 Patriot Drive Suite A Middletown DE 19709 302-274-8744 Galbraith, Kenneth Officer Director Common Stock Morgan Stanley

1585 Broadway New York NY 10036

57291 828428 68877526 01/06/2025 Nasdaq Common Stock 01/06/2025 Vesting of Restricted Stock Units Issuer N 47666 01/06/2025 Vesting of Award Common Stock 01/06/2025 Vesting of Restricted Stock Units Issuer N 66666 01/06/2025 Vesting of Award Y The shares of common stock to be sold represent shares to be sold to cover tax withholding obligations and other fees in connection with the vesting of RSUs pursuant to mandatory "sell to cover" provisions contained in the applicable RSU grant agreement. 01/06/2025 /s/ Kenneth Galbraith