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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to or Delaware ( State or Other Jurisdiction of Incorporation or Organization ) 42307 Osgood Road , Suite I , Fremont , California ( Address of Principal Executive Offices ) Title of Each Class Class A Common Stock , $ 0.0001 par value Commission file number : 001-38273 0 ACM RESEARCH ACM Research , Inc. ( Exact Name of Registrant as Specified in Its Charter ) Large accelerated filer Non - accelerated filer 0 Registrant's telephone number , including area code : ( 510 ) 445-3700 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ACMR 94-3290283 Class Class A Common Stock , $ 0.0001 par value Class B Common Stock , $ 0.0001 par value ( I.R.S. Employer Identification No. ) 94539 ( Zip Code ) 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 No 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 No 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 Name of Each Exchange on which Registered NASDAQ Global Market 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 ( §232.405 of this chapter ) 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 definitions of “ large accelerated filer , ” “ accelerated filer , ” “ smaller reporting company ” and “ emerging growth company ” in Rule 12b - 2 of the Exchange Act . 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 . 0 П 0 Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of 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 . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No The aggregate market value on June 30 , 2020 ( the last business day of the registrant's most recently completed second quarter ) of the voting common equity held by non affiliates of the registrant , computed by reference to the $ 62.36 closing price of the stock on that date , was $ 735.7 million . The registrant does not have non - voting common equity outstanding . Indicate the number of shares outstanding of each of the registrant's classes of common stock , as of the latest practicable date . Number of Shares Outstanding 16,967,095 shares outstanding as of February 23 , 2021 1,775,939 shares outstanding as of February 23 , 2021 Documents Incorporated By Reference The registrant intends to file a proxy statement pursuant to Regulation 14A within 120 days of the end of the fiscal year ended December 31 , 2020. Portions of such proxy statement are incorporated by reference in Part III of this report .