REGULATION FD DISCLOSURES Zymeworks BC Inc. (“Zymeworks”), a subsidiary of the Company, is a party to an Amended and Restated License and Collaboration Agreement (as amended, the “License and Collaboration Agreement”) with Jazz Pharmaceuticals Ireland Limited, a subsidiary of Jazz Pharmaceuticals plc, collectively referred to as “Jazz,” granting Jazz exclusive rights to develop and commercialize Zymeworks’ proprietary bispecific HER2 antibody product candidate known as zanidatamab throughout…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 6, 2026, Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three months ended June 30, 2026. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).

Entry into a Material Definitive Agreement Agreement and Plan of Merger On June 28, 2026, Zymeworks Inc., a Delaware corporation (“Zymeworks” or “Parent”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Zymeworks Merger Sub 1, an exempted company with limited liability incorporated under the Laws of the Cayman Islands and a wholly owned subsidiary of Parent (“Merger Sub”), and Theravance Biopharma, Inc., an exempted company with limited liability incorporated under…

Regulation FD Disclosure On June 29, 2026, Zymeworks issued a press release announcing the parties’ entry into the Merger Agreement. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. Also on June 29, 2026, Zymeworks intends to hold a conference call available to investors and the public. Details for accessing the conference call can be found in the press release furnished as Exhibit 99.1 to this Current Report. A presentation for reference…

of this Current Report on Form 8-K is being furnished and shall not be deemed to be “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be incorporated by reference into any registration statement or other document filed pursuant to the Securities Act or the Exchange Act, regardless of any general incorporation language contained in such, unless the Company specifically states that the information is to be considered “…

Other Events. On May 14, 2026, Zymeworks Inc. (the “Company”) issued a press release announcing that its Board of Directors (the “Board”) had authorized a share repurchase program (the “2026 Share Repurchase Program”) under which the Company may repurchase up to $125.0 million of the Company’s common stock, par value $0.00001 per share (the “Common Stock”). In connection with approval of the 2026 Share Repurchase Program, the Board terminated the previous authorization of up to $125.0 million…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On May 7, 2026, Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three months ended March 31, 2026. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).

Executive Vice President, Chief Financial Officer — Ms. Kristin Stafford: The company hired a new Chief Financial Officer from an external candidate.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On March 2, 2026 , Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three months and year ended December 31, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information in

Entry into a Material Definitive Agreement. On March 2, 2026, Zymeworks BC Inc. (“ Zymeworks BC ”), a subsidiary of Zymeworks Inc. (the “ Company ”), entered into a sale agreement (the “ Sale Agreement ”) with Zymeworks Royalty Limited Partnership (the “ Subsidiary ”), a special purpose entity newly formed by Zymeworks BC and by its general partner Zymeworks General Partner ULC (“ Zymeworks GP ”), the Company solely for the purpose of certain indemnification provisions thereunder, and Royalty…

Results of Operations and Financial Condition. On January 11, 2026, Zymeworks Inc. (the “Company”) announced certain information relating to the Company’s financial condition as of December 31, 2025, including its preliminary and unaudited estimate of cash resources, which consist of cash, cash equivalents and marketable securities, of approximately $270.6 million. The Company also announced that, based on current operating plans and existing cash resources, and assuming full execution of the…

Director — Mr. Brian Cherry: Mr. Brian Cherry was appointed as a Class II director of the Company.

of this Current Report on Form 8-K and Exhibit 99.2 are being furnished and shall not be deemed to be “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be incorporated by reference into any registration statement or other document filed pursuant to the Securities Act or the Exchange Act, regardless of any general incorporation language contained in such, unless the Company specifically states that the information is…

Director — Mr. Scott Platshon: Mr. Scott Platshon resigned from the board of directors with no specified successor.

Other Events. On November 18, 2025, the Company issued a press release announcing a strategic initiative focused on optimizing future cash flows from Ziihera ® (zanidatamab-hrii), other licensed products and other healthcare assets, as well as that its Board had authorized a share repurchase program under which the Company may repurchase up to $125.0 million of the Company’s common stock, par value $0.00001 per share (the “Share Repurchase Program”). A copy of the press release announcing the…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On November 6, 2025, Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three and nine months ended September 30, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).

Entry into a Material Definitive Agreement. The information set forth under

Director — Messrs. Gregory A. Ciongoli and Robert E. Landry: Two new directors were appointed to the board, and one director resigned without any disagreement.

Unregistered Sales of Equity Securities. The information set forth under

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 7, 2025, Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three and six months ended June 30, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).

Unregistered Sales of Equity Securities. As previously disclosed in a Current Report on Form 8-K filed by the Company with the U.S. Securities and Exchange Commission (the “SEC”) on December 26, 2023, the Company entered into the Purchase Agreement with the Purchasers, pursuant to which the Purchasers purchased 5,086,521 Pre-Funded Warrants to purchase 5,086,521 shares of Common Stock. The per share purchase price for the Pre-Funded Warrants was $9.8299, for an aggregate purchase price of app…

Entry into a Material Definitive Agreement. Amendment to Pre-Funded Warrants On June 26, 2025, Zymeworks Inc. (the “Company”) entered into an amendment (the “Amendment”) to the outstanding Pre-Funded Warrants to Purchase Shares of Common Stock (the “Pre-Funded Warrants”), issued on December 28, 2023 to EcoR1 Capital Fund, L.P. (“EcoR1”) and EcoR1 Capital Fund Qualified, L.P. (together with EcoR1, the “Purchasers”) pursuant to the Securities Purchase Agreement, dated December 23, 2023, by and…

ENTRY INTO A MATERIAL DEFINITIVE AGREEMENT On November 26, 2018, Zymeworks Inc. (“Zymeworks”) entered into the following agreements with BeiGene, Ltd. (“BeiGene”): (i) two license and collaboration agreements (the “ZW25 Agreement” and the “ZW49 Agreement” and together, the “Product Candidate Agreements”) granting BeiGene exclusive rights to research, develop, and commercialize Zymeworks’ product candidates, ZW25 and ZW49, in Asia (excluding Japan but including the People’s Republic of China,…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On May 8, 2025, Zymeworks Inc. (the “Company”) issued a press release announcing its financial results for the three months ended March 31, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Form 8-K”).