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Delaware ( State of incorporation ) 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 Title of Each Class Common Stock , $ 0.001 par For the Fiscal Year Ended December 31 , 2020 Commission File Number 000-29472 value Amkor Technology , Inc. ( Exact name of registrant as specified in its charter ) 2045 East Innovation Circle Tempe , AZ 85284 ( 480 ) 821-5000 ( Address of principal executive offices and zip code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol AMKR 23-1722724 ( I.R.S. Employer Identification Number ) Name of Each Exchange on Which Registered The NASDAQ Global Select Market Securities registered pursuant to Section 12 ( g ) of the Act : None 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 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 , as amended , 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 No 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 . ( Check one ) : Large accelerated filer Accelerated filer Non - 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 . o 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 . No D Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes The aggregate market value of the voting and non - voting common equity held by non - affiliates of the registrant as of June 30 , 2020 , based upon the closing price of the common stock as reported by the NASDAQ Global Select Market on that date , was approximately $ 1,222 million . The number of shares outstanding of each of the issuer's classes of common equity , as of February 12 , 2021 , was as follows : 243,341,709 shares of Common Stock , $ 0.001 par value . DOCUMENTS INCORPORATED BY REFERENCE : Portions of the registrant's Proxy Statement relating to its 2021 Annual Meeting of Stockholders , to be filed subsequently , are incorporated by reference into Part III of this Report where indicated .