X0508 4 2023-09-29 0001704292 Zai Lab Ltd ZLAB 0001985694 Chen Yajing C/O ZAI LAB LIMITED 314 MAIN STREET, 4TH FLOOR, SUITE 100 CAMBRIDGE MA 02142 true Chief Financial Officer false American Depositary Shares 2023-09-29 4 M 0 920 A 6954 D American Depositary Shares 2023-09-29 4 F 0 307 24.31 D 6647 D Restricted Share Units 2023-09-29 4 M 0 920 0 D American Depositary Shares 920 2760 D Each American Depositary Share (ADS) represents ten Ordinary Shares of the issuer. Our ADSs and Ordinary Shares are fully fungible. For purposes of this Form 4, we are reporting this in terms of ADSs. ADSs acquired on vesting of Restricted Share Units. Each ADS represents ten Ordinary Shares of the issuer. Each Restricted Share Unit represents a contingent right to receive one ADS, which represents ten Ordinary Shares of the issuer. This transaction represents the disposition of shares to the issuer to cover taxes. This number reflects a net reduction of 39,930 ADSs, which represents Restricted Share Units that were previously reported as aggregated with ADSs in Table I and are now separately reported in Table II. The Restricted Share Units vest in equal annual installments over five years beginning on 10/01/2022, the first anniversary of the date of grant. Vested shares will be delivered to the reporting person following vesting. /s/ Bruce Blefeld, Attorney-in-Fact 2023-10-03