Zai Lab Limited — Capital/Financing Update 2021

Apr 28, 2021

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.

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**Zai Lab Limited 再鼎醫藥有限公司 ***

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 9688)

VOLUNTARY ANNOUNCEMENT

CLOSING OF OFFERING OF ORDINARY SHARES

Reference is made to the announcement of Zai Lab Limited (the “ Company ”) dated April 25, 2021 in relation to the closing of the ADS Offering in the United States (the “ Announcement ”). Unless otherwise defined, terms used in this announcement shall have the same meanings as those defined in the Announcement.

CLOSING OF OFFERING OF ORDINARY SHARES

The board of directors of the Company is pleased to announce that the closing of the underwritten offering of 224,000 ordinary shares of the Company (the “ Ordinary Shares Offering ”) took place on April 28, 2021 (Hong Kong time), at a price of HK$1,164.20 per ordinary share.

The expected total global offering gross proceeds to the Company, including both the ADS Offering and the Ordinary Shares Offering, are approximately US$857.50 million.

This announcement does not constitute an offer to sell or the solicitation of an offer to buy ADSs, ordinary shares, or any other securities, nor shall there be any sale of ADSs or ordinary shares in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities law of any such state or jurisdiction. The ADSs were offered pursuant to a shelf registration statement on Form S-3ASR, which became automatically effective upon filing with the SEC on April 19, 2021 (U.S. Eastern Time). The ADS Offering was made only by means of a prospectus supplement and an accompanying prospectus included in Form S-3ASR. The registration statement on Form S-3ASR and the prospectus supplement are available at the SEC’s website at: http://www.sec.gov. Copies of the prospectus supplement and the accompanying prospectus may be obtained from: (i) J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, via telephone at 1-866-803-9204 or via email at prospectus-eq_fi@jpmchase.com, (ii) Goldman Sachs & Co. LLC, Prospectus Department, 200 West Street, New York, NY 10282, telephone: 1-866-471-2526, facsimile: 212-902-9316 or by emailing Prospectus-ny@ny.email.gs.com, (iii) Jefferies LLC, Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York 10022, or by telephone

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at 1-877-821-7388 or via email at prospectus_department@jefferies.com and (iv) Citigroup Capital Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717 or by telephone at 1-800-831-9146.

FORWARD LOOKING STATEMENT

This announcement contains references to statements about future expectations, plans and prospects for the Company, including, without limitation, statements containing words such as “aim”, “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “seek,” “target,” “potential,” “will,”, “would,” “could,” “should,” “continue,” “contemplate” and other similar expressions. Such statements constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are neither historical facts nor assurances of future performance. Forward-looking statements are based on the Company’s expectations and assumptions that the Company believes are reasonable as of the date of this announcement and are subject to inherent uncertainties, risks and changes in circumstances that may differ materially from those contemplated by the forward-looking statements. Actual results of operations, financial condition and liquidity, and the development of the industry in which the Company operates may differ materially from those indicated by such forward-looking statements as a result of various important factors, including but not limited to (1) the Company’s ability to successfully commercialize and generate revenue from its approved products; (2) the Company’s ability to finance its operations and business initiatives and obtain funding for such activities, (3) the Company’s results of clinical and pre-clinical development of its product candidates, (4) the content and timing of decisions made by the relevant regulatory authorities regarding regulatory approvals of the Company’s product candidates, (5) the effects of the novel coronavirus (COVID-19) pandemic on general economic, regulatory and political conditions and (6) other factors discussed in the Company’s annual report on Form 10-K for the fiscal year ended December 31, 2020, filed on March 1, 2021, and its other filings with the SEC. The Company anticipates that subsequent events and developments will cause the Company’s expectations and assumptions to change and undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required by law. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date of this announcement.

By order of the Board Zai Lab Limited Samantha Du Director, Chairperson and Chief Executive Officer

Hong Kong, April 28, 2021

As at the date of this announcement, the board of directors of the Company comprises Dr. Samantha Du and Mr. Tao Fu as the directors, and Dr. Kai-Xian Chen, Dr. John Diekman, Ms. Nisa Leung, Mr. William Lis, Mr. Leon O. Moulder, Jr. and Mr. Peter Wirth as the independent directors.

• For identification only

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