X0508 4 2026-03-04 0001704292 Zai Lab Ltd ZLAB 0001985694 Chen Yajing C/O ZAI LAB LIMITED 314 MAIN STREET, 4TH FLOOR, SUITE 100 CAMBRIDGE MA 02142 false true false false Chief Financial Officer false American Depositary Shares 2026-03-12 4 M false 4258 A 21702 D American Depositary Shares 2026-03-13 4 S false 1703 18.628 D 19999 D Stock Options (Right to Buy) 19.27 2026-03-04 4 A false 83160 0 A 2036-03-04 American Depositary Shares 83160 83160 D Restricted Share Units 2026-03-04 4 A false 27027 0 A American Depositary Shares 27027 27027 D Restricted Share Units 2026-03-12 4 M false 4258 0 D American Depositary Shares 4258 12777 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 upon vesting of Restricted Share Units ("RSUs"). Each RSU represents a contingent right to receive one ADS. These ADSs were sold automatically to cover taxes upon vesting of RSUs. The option vests in equal annual installments over four years beginning on 03/04/2027, the first anniversary of the date of grant, subject to continuous service. The RSUs vest in equal annual installments over four years beginning on 03/04/2027, the first anniversary of the date of grant, subject to continuous service. Vested shares will be delivered in the form of ADSs to the reporting person following vesting. The RSUs vest in equal annual installments over four years beginning on 03/12/2026, the first anniversary of the date of grant, subject to continuous service. Vested shares will be delivered in the form of ADSs to the reporting person following vesting. /s/ Bruce Blefeld, Attorney-in-Fact 2026-03-16