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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( MARK ONE ) X ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended June 30 , 2021 OR ■ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ Commission file number 001-34717 Alpha and Omega Semiconductor Limited ( Exact name of Registrant as Specified in its Charter ) 4 Title of each class Common Shares , $ 0.002 par value per share ALPHA & OMEGA SEMICONDUCTOR Bermuda ( State or Other Jurisdiction of Incorporation or Organization ) Clarendon House , 2 Church Street Hamilton HM 11 , Bermuda ( Address of Principal Registered Offices including Zip Code ) 77-0553536 ( I.R.S. Employer Identification Number ) ( 408 ) 830-9742 ( Registrant's Telephone Number , Including Area Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . AOSL Name of each exchange on which registered The NASDAQ Global Select Market 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 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 and posted 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 . ( Check one ) : Large accelerated filer ■ Accelerated filer Non - accelerated filer ( Do not check if a smaller reporting company ) Smaller reporting company ☐ Emerging growth company L ■ 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 . 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 of the voting shares held by non - affiliates of the registrant as of December 31 , 2020 was approximately $ 487 million based on the closing price of the registrant's common share as reported on the NASDAQ Global Select Market on December 31 , 2020 ( the last business day of the registrant's most recently completed second fiscal quarter ) . The common shares of the registrant held by each executive officer and director and certain affiliated shareholders who beneficially owned 10 % or more of the outstanding common stock of the registrant have been excluded in such calculation as such