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Table of Contents Table of Contents ✓ 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 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from Commission file number 0-18277 VICOR CORPORATION ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 25 Frontage Road , Andover , Massachusetts ( Address of principal executive offices ) Title of each class Common Stock , par value $ 0.01 per share to Large Accelerated Filer Emerging growth company Registrant's telephone number , including area code : ( 978 ) 470-2900 Securities registered pursuant to Section 12 ( b ) of the Act : Accelerated Filer Trading Symbol ( s ) VICR 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 Securities registered pursuant to Section 12 ( g ) of the Act : None 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 04-2742817 ( IRS employer identification no . ) 01810 ( Zip code ) Name of each exchange on which registered The NASDAQ Stock Market LLC 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 . Title of Each Class Common Stock Class B Common Stock Non - accelerated Filer Smaller Reporting 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 . No 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 of the registrant held by non - affiliates ( for this purpose , persons and entities other than executive officers and directors ) of the registrant , as of the registrant's most recently completed second fiscal quarter ( June 30 , 2020 ) was approximately $ 1,454,187,000 . Number of Shares of Common Stock Outstanding as of February 18 , 2021 31,658,143 11,758,218 DOCUMENTS INCORPORATED BY REFERENCE Portions of the Company's definitive proxy statement ( the “ Definitive Proxy Statement " ) to be filed with the Securities and Exchange Commission pursuant to Regulation 14A and relating to the Company's 2021 annual meeting of stockholders are incorporated by reference into Part III .