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( Mark One ) ☐ UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 20 - F REGISTRATION STATEMENT PURSUANT TO SECTION 12 ( b ) OR 12 ( g ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR 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 OR ☐ SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES ACT OF 1934 * Title of Each Class Commission file number : 001-16125 日月光 投資 控股 股份有限公司 ( Exact name of Registrant as specified in its charter ) ASE Technology Holding Co. , Ltd. ( Translation of Registrant's name into English ) REPUBLIC OF CHINA ( Jurisdiction of incorporation or organization ) 26 , Chin 3rd Road Kaohsiung , Taiwan Republic of China ( Address of principal executive offices ) Joseph Tung Room 1901 , No. 333 , Section 1 Keelung Rd . Taipei , Taiwan , 110 Republic of China Tel : 886-2-6636-5678 Fax : 882-2-2757-6121 Email : ir@aseglobal.com ( Name , Telephone , E - mail and / or Facsimile number and Address of Company Contact Person ) Common Shares , par value NT $ 10.00 each Securities registered or to be registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) ASX Name of Each Exchange on which Registered The New York Stock Exchange * Traded in the form of American Depositary Receipts evidencing American Depositary Shares ( the " ADSS " ) , each representing two common shares of ASE Technology Holding Co. , Ltd. Securities registered or to be registered pursuant to Section 12 ( g ) of the Act : None Securities for which there is a reporting obligation pursuant to Section 15 ( d ) of the Act : None Indicate the number of outstanding shares of each of the issuer's classes of capital or common stock as of the close of the period covered by the annual report . As of December 31 , 2020 , 4,350,675,482 Common Shares , par value NT $ 10 each were outstanding . ** Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes ☑ No □ If this report is an annual or transition report , indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 . Yes □ No ☑