Zymeworks Inc. — Director's Dealing 2025

Dec 22, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Zymeworks Inc. (ZYME)
CIK: 0001937653
Period of Report: 2025-12-22

Reporting Person: Galbraith Kenneth (N/A)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-12-22	Common Stock	M	100000	$0.00	Acquired	180803	Direct
2025-12-22	Common Stock	S	47528	$27.0222	Disposed	133275	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-12-22	Restricted Stock Unit	$	M	100000	Disposed	2025-12-22	Common Stock (100000)	Direct

Footnotes

F1: Represents shares of common stock issued upon vesting of restricted stock units ("RSUs") granted on December 22, 2022.

F2: 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.

F3: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $26.83 to $27.16 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.

F4: Each RSU represents the contingent right to receive, upon vesting of the RSU, one share of the Issuer's common stock.

F5: The RSUS vested on December 22, 2025.