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Table of Contents ( Mark One ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ☑ Annual Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 For the fiscal year ended : December 31 , 2020 Or ☐ Transition Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 Cayman Islands Commission file number : 001-38205 ZAI LAB LIMITED ( Exact Name of Registrant as Specified in its Charter ) ( State or other jurisdiction of incorporation or organization ) 4560 Jinke Road Bldg . 1 , Fourth Floor Pudong Shanghai , China ( Address of principal executive offices ) Title of each class American Depositary Shares , each representing 1 Ordinary Share , par value $ 0.00006 per share Ordinary Shares , par value $ 0.00006 per share * +86 21 6163 2588 ( Registrant's Telephone Number , Including Area Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) ZLAB 9688 98-1144595 ( I.R.S. Employer Identification No. ) 201210 ( Zip Code ) Name of each exchange on which registered The Nasdaq Global Market The Stock Exchange of Hong Kong Limited Included in connection with the registration of the American Depositary Shares with the Securities and Exchange Commission . The ordinary shares are not registered or listed for trading in the United States but are listed for trading on The Stock Exchange of Hong Kong Limited . Securities registered pursuant to Section 12 ( g ) of the Act : None No □ No Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes ☑ Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Exchange Act . Yes Indicate by check mark whether the registrant : ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes > No ☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes No □ Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company ” in Rule 12b - 2 of the Exchange Act .: Large accelerated filer Non - accelerated filer ☑ ☐ ㅁ Accelerated Filer Smaller reporting company Emerging growth company ☐ ☐ If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . ☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Yes × No □ Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No As of June 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter , the aggregate market value of the ordinary shares , including in the form of American Depositary Shares ( " ADSS " ) , each representing one ordinary share , held by non - affiliates of the registrant was approximately US $ 6.2 billion , based upon the closing price of the registrant's ADSs on the Nasdaq Global Market of US $ 82.13 on June 30 , 2020 . As of February 26 , 2021 , 88,592,343 ordinary shares , par value $ 0.00006 per share , were outstanding , of which 60,078,450 ordinary shares were held in the form of ADSs . DOCUMENTS INCORPORATED BY REFERENCE The registrant intends to file a definitive proxy statement pursuant to Regulation 14A within 120 days of the end of the fiscal year ended December 31 , 2020. Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10 - K .