Sec Form 3 Filing - Mekan Sabeen @ Zymeworks Inc. - 2026-02-01

FORM 3 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 Mekan Sabeen 2. Issuer Name and Ticker or Trading Symbol Zymeworks Inc. [ ZYME] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) SVP & Chief Medical Officer (Last) (First) (Middle) C/O ZYMEWORKS INC., 108 PATRIOT DRIVE, SUITE A 3. Date of Earliest Transaction (MM/DD/YY) 02/01/2026 (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 No securities are beneficially owned 0 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 Stock Option (Right to Buy) $ 11.75 ( 1 )( 2 ) 04/20/2035 Common Stock 192,000 D Stock Option (Right to Buy) $ 23.16 ( 2 )( 3 ) 01/11/2036 Common Stock 29,000 D Restricted Stock Unit ( 5 ) ( 4 ) ( 4 ) Common Stock 19,000 D Performance Stock Unit ( 6 ) ( 7 ) ( 6 )( 7 ) ( 6 )( 7 ) Common Stock 32,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Mekan Sabeen C/O ZYMEWORKS INC. 108 PATRIOT DRIVE, SUITE A MIDDLETOWN, DE19709 SVP & Chief Medical Officer Signatures /s/ Catherine Graham, Attorney-in-Fact 02/02/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Stock option granted April 21, 2025. ( 2 )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. ( 3 )Stock option granted January 12, 2026. ( 4 )Restricted stock units ("RSUs") granted January 12, 2026. RSUs vest in four equal annual installments beginning on first anniversary of grant date. ( 5 )Each RSU represents the contingent right to receive, upon vesting of the RSU, one share of common stock. ( 6 )Performance restricted stock units ("PSUs") granted January 12, 2026. Each PSU represents a contingent right to receive one share of common stock. The amount reported is the maximum number of PSUs that may be earned upon achievement of certain cumulative total shareholder return ("TSR") goals over a three-year performance period ending on January 12, 2029 (or in some cases at earlier times). Between 50% and 200% of the target number of 16,000 PSUs ("Target Number") may be earned upon achievement of such TSR goals. 50% of the Target Number may be earned upon achievement of relative TSR goals if the Company's TSR for the performance period equals or exceeds a prespecified percentile for the Nasdaq Biotech Index. ( 7 )(Continued from footnote 6) The PSUs will only vest at the end of the three-year performance period if the Reporting Person's service to the Company continues through such time that the board of directors of the Company certifies the achievement of TSR goals, except in certain limited cases (such as if service to the Company is terminated by the Company without cause or in case of a change of control).

Remarks: Exhibit List - Exhibit 24 - Power of Attorney

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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