Zai Lab Ltd

On November 10, 2025, Dr. Samantha (Ying) Du, the Company’s Founder, Chief Executive officer, and Chairperson of the Board, adopted a new written Rule 10b5-1 trading arrangement, for (1) the acquisition and sale of up to 400,000 ADSs upon the exercise of previously awarded options that are scheduled to expire in 2026 and (2) for the acquisition of up to 261,092 ADSs upon the exercise of previously awarded options that are scheduled to expire in 2026. This Rule 10b5-1 trading arrangement is scheduled to terminate no later than November 9, 2026.

On November 14, 2025, Rafael Amado, the Company’s President and Head of Global Research and Development, adopted a new written Rule 10b5-1 trading arrangement for the sale of up to 20,000 ADSs. This Rule 10b5-1 trading arrangement is scheduled to terminate no later than December 17, 2026.

On December 16, 2025, Richard Gaynor, one of the Company’sdirectors, adopted a new written Rule 10b5-1 trading arrangement for the purchase of ADSs with a price of up to $99,000. This Rule 10b5-1 trading arrangement is scheduled to terminate no later than December 31, 2026.

Other than as described above, during the fourth quarter of 2025, none of our directors or executive officers (as defined in Rule 16a-1(f) under the Exchange Act) hasadopted orterminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement (each as defined in Item 408 of Regulation S-K).

On February 24, 2026, Zai Lab US entered into an amendment to its employment agreement dated August 1, 2022 with Josh Smiley, the Company’s President and Chief Operating Officer. The amendment expands Mr. Smiley’s severance benefits so that he will be entitled to 12 months of base salary, 12 months of COBRA continuation benefits, and a pro-rated

-91- target bonus upon any termination by the Company without cause or by the employee for good reason (each of these terms as defined in the employment agreement). Otherwise, Mr. Smiley’s compensation and benefits remain unchanged.

In addition, on February 24, 2026, Zai Lab US entered into an employment agreement with Yajing Chen, the Company’s Chief Financial Officer, which replaces Dr. Chen’s letter agreement dated July 6, 2023. The employment agreement expands Dr. Chen’s severance benefits upon certain termination events (each of the terms below as defined in the employment agreement). Specifically, upon a termination due to death or disability, Dr. Chen will be entitled to one month of base salary and one month of COBRA continuation benefits. Upon a termination by the Company without cause or by the employee for good reason, Dr. Chen will be entitled to 12 months of base salary, 12 months of COBRA continuation benefits, and a pro-rated target bonus. Upon a termination by the Company without cause or by the employee for good reason following a change in control, Dr. Chen will be entitled to 12 months of base salary, 12 months of COBRA continuation benefits, a pro-rated target bonus, and accelerated vesting of outstanding equity awards. Otherwise, Dr. Chen’s compensation and benefits remain unchanged.

On February 25, 2026, the Company entered into a new revolving credit facility with BOCOM, which replaced its previous RMB300.0 million (approximately $41.1 million) credit facility that expired in September 2025. The Company entered into a new guarantee contract with BOCOM pursuant to which the Company will provide a maximum-amount guarantee of RMB330.0 million (approximately $47.9 million) for working capital loans of up to RMB300.0 million (approximately $43.6 million) from BOCOM to Zai Lab Shanghai, and Zai Lab Shanghai entered into a working capital loan contract with BOCOM with respect to the RMB300.0 million facility. The new credit facility will be available until February 2, 2029, and key terms of the specific working capital loans, including the amount, term, and interest rate, will be included in the specific transaction documents. Each loan term will be up to 12 months, with a maturity date no later than August 2, 2029, and the interest rate will be initially determined based on the one-year loan prime rate (“LPR”) immediately preceding the drawdown date minus 50 basis points and will be subject to adjustment every three months depending on the then one-year LPR and the then latest permissible lower limit on interest rate, and will be adjusted to the then latest permissible lower limit on interest rate when it becomes higher than the then interest rate. The working capital loan contract contains customary representations and warranties and affirmative and restrictive covenants, including a requirement to obtain prior written consent from BOCOM before engaging in certain transactions that could have an adverse impact on its debt repayment ability, such as mergers, acquisitions, spin-offs, equity transfers, external investments or guarantees exceeding RMB1.0 billion (approximately $145.3 million), and increases in debt financings exceeding RMB1.5 billion (approximately $217.9 million).