Sec Form 4 Filing - Galbraith Kenneth @ Zymeworks Inc. - 2024-01-05

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Galbraith Kenneth 2. Issuer Name and Ticker or Trading Symbol Zymeworks Inc. [ ZYME] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chair & CEO (Last) (First) (Middle) C/O ZYMEWORKS INC., 108 PATRIOT DRIVE, SUITE A 3. Date of Earliest Transaction (MM/DD/YY) 01/05/2024 (Street) MIDDLETOWN, DE19709 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 01/05/2024 M 47,666 A $ 0 ( 1 ) 47,666 D Common Stock 01/05/2024 S( 2 ) 18,198 D $ 10.6522 ( 3 ) 29,468 D Common Stock 01/08/2024 S( 2 ) 5,706 D $ 11.2156 ( 4 ) 23,762 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Restricted Stock Unit ( 5 ) 01/05/2024 M 47,666 ( 6 ) ( 6 ) Common Stock 47,666 $ 0 95,334 D Stock Option (Right to Buy) $ 10.56 01/05/2024 A 300,000 ( 7 ) 01/04/2034 Common Stock 300,000 $ 0 300,000 D Restricted Stock Unit ( 5 ) 01/05/2024 A 200,000 ( 8 ) ( 8 ) Common Stock 200,000 $ 0 200,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Galbraith Kenneth C/O ZYMEWORKS INC. 108 PATRIOT DRIVE, SUITE A MIDDLETOWN, DE19709 X Chair & CEO Signatures /s/ Daniel Dex, Attorney-in-Fact 01/08/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares of common stock issued upon vesting of one third of the restricted stock units ("RSUs") granted on January 5, 2023. ( 2 )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. ( 3 )The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $10.55 to $10.845, 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. ( 4 )The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $10.49 to $11.58, 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. ( 5 )Each RSU represents the contingent right to receive, upon vesting of the RSU, one share of the Issuer's common stock. ( 6 )The RSUS were granted on January 5, 2023 and vest in three equal annual installments beginning on January 5, 2024. ( 7 )Stock options vest as follows: (i) 25% of underlying shares of common stock on first anniversary of grant date and (ii) remainder of underlying shares of common stock in 36 equal monthly installments on last day of month following first anniversary of grant date. ( 8 )The RSUs vest in three equal annual installments beginning on January 5, 2025.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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