Zai Lab Limited — Share Issue/Capital Change 2026

Jun 3, 2026

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.

Zai Lab Limited

再鼎醫藥有限公司*

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 9688)

GRANT OF RESTRICTED SHARE UNITS

This announcement is made pursuant to Rules 17.06A, 17.06B and 17.06C of the Listing Rules. The Board announces that, on the Date of Grant, the Company granted certain Restricted Share Units under the 2024 Equity Incentive Plan.

GRANT OF RESTRICTED SHARE UNITS

Number of Grantee: 1

Type of Grantee: Employee Participant

Number of the Restricted Share Units granted (in ADSs): 500

Number of underlying Shares pursuant to the Restricted Share Units granted: 5,000

Purchase price of the Restricted Share Units granted: Nil

Closing price of the Shares on the Date of Grant: US$17.09 per ADS (approximately HK$13.33 per Share) as quoted on NASDAQ on June 1, 2026 (U.S. Eastern Time)

HK$13.57 per Share as quoted on the Stock Exchange on June 1, 2026 (Hong Kong time)

Vesting period of the Restricted Share Units 25% of the Restricted Share Units granted shall vest on each anniversary of the Date of Grant for the next four years, subject

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granted: to the Grantee’s continued employment relationship with the Group up to each vesting date.

Performance target(s) and/or clawback mechanism: There are no performance targets attached to the vesting of the Restricted Share Units. The grant is not subject to any clawback mechanism for the Company to recover but would be subject to tax withholding by the Company pursuant to the terms and conditions of the 2024 Equity Incentive Plan.

The Compensation Committee of the Board is of the view that, given the Restricted Share Units will be vested in multiple tranches subject to the Grantee’s continued employment with the Group and were granted for the reasons set out in the section headed “REASONS FOR AND BENEFITS OF THE GRANT” below, the grant of Restricted Share Units to the Grantee without performance targets or a clawback mechanism is market competitive, consistent with the Company’s customary practice, and align with the purpose of the 2024 Equity Incentive Plan.

The grant of Restricted Share Units is subject to the terms and conditions of the 2024 Equity Incentive Plan and form of award agreement covering the grant.

REASONS FOR AND BENEFITS OF THE GRANT

The grant of Restricted Share Units is to recognize and reward the Grantee for contribution to the Group, and to provide additional incentives to the Grantee to maintain and further promote the success of the Group’s business.

OTHER INFORMATION

The Grantee is an Employee Participant. The Grantee is neither (i) a Director, a chief executive, a substantial shareholder of the Company, or an associate of any of them; (ii) a senior manager of the Company; (iii) a participant with options and awards granted and to be granted exceeding the 1% individual limit under Rule 17.03D(1) of the Listing Rules; nor (iv) a related entity participant or service provider with options and awards granted and to be granted in any 12-month period exceeding 0.1% of the total issued Shares (excluding treasury shares).

There are no arrangements for the Company or any of its subsidiaries to provide financial assistance to the Grantee to facilitate the purchase of Shares under the 2024 Equity Incentive Plan.

NUMBER OF SHARES AVAILABLE FOR FUTURE GRANTS

Following the grant above, 61,650,583 Shares remain available for future grants under the scheme mandate limit of the 2024 Equity Incentive Plan.

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DEFINITIONS

"2024 Equity Incentive Plan" the Zai Lab Limited 2024 Equity Incentive Plan approved at the Company's 2024 annual general meeting of shareholders and effective on June 18, 2024, the principal terms of which were set out in the Company's definitive proxy statement/ circular dated April 30, 2024

"ADS(s)" American depositary share(s) (each representing 10 Shares)

"associate" has the meaning ascribed to it under the Listing Rules

"Board" the board of directors of the Company

"Company" Zai Lab Limited, a company incorporated in the Cayman Islands with limited liability and listed on the Main Board of the Stock Exchange (Stock Code: 9688) and NASDAQ (Trading Symbol: ZLAB)

"Date of Grant" June 1, 2026 (U.S. Eastern Time)

"Director(s)" member(s) of the Board

"Employee Participant" an eligible participant under the 2024 Equity Incentive Plan who is a director, officer or employee of the Group on the Date of Grant

"Grantee(s)" eligible participant(s) under the 2024 Equity Incentive Plan who were granted the Restricted Share Units under the 2024 Equity Incentive Plan on the Date of Grant

"Group" the Company and its subsidiaries

"HK$" the lawful currency of Hong Kong

"Hong Kong" Hong Kong Special Administrative Region of the People's Republic of China

"Listing Rules" the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited

"NASDAQ" Nasdaq Global Market

"Restricted Share Unit(s)" share unit(s) subject to the satisfaction of specified service-based vesting conditions

"senior manager" has the meaning ascribed to it under Chapter 17 of the Listing Rules

"Share(s)" ordinary share(s) in the authorized share capital of the Company

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with a par value of US$0.000006 per share

"Stock Exchange" The Stock Exchange of Hong Kong Limited

"subsidiary(ies)" has the meaning ascribed to it under the Listing Rules

"substantial shareholder" has the meaning ascribed to it under the Listing Rules

"treasury shares" has the meaning ascribed to it under the Listing Rules

For the purpose of this announcement and for illustrative purpose only, conversions of US$ to HK$ are based on the exchange rate of US$1.00 = HK$7.8. No representation is made that any amounts in HK$ or US$ can be or could have been converted at the relevant dates at the above rate or at any other rates or at all.

Except as otherwise specified, all references in this announcement to times and dates are references to Hong Kong times and dates.

By order of the Board

Zai Lab Limited

Samantha Du

Director, Chairperson and Chief Executive Officer

Hong Kong, June 3, 2026

As at the date of this announcement, the board of directors of the Company comprises Dr. Samantha Du and Mr. Leon O. Moulder Jr. as directors, and Dr. John Diekman, Dr. Richard Gaynor, Ms. Nisa Leung, Mr. William Lis, Mr. Scott W. Morrison, Mr. Michel Vounatsos and Mr. Peter Wirth as independent directors.

• For identification only