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Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE FORM 10 - K TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from Delaware ( State or other jurisdiction of incorporation or organization ) RITIES EXCHANGE ACT OF 1934 For the fiscal year ended March 31 , 2021 OR 1521 Westbranch Drive , Suite 100 McLean , Virginia ( Address of principal executive offices ) Large accelerated filer Non - accelerated filer GLADSTONE INVESTMENT CORPORATION ( Exact name of registrant as specified in its charter ) to Commission file number 814-00704 ( 703 ) 287-5800 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) GAIN GAINL GAINN 83-0423116 ( I.R.S. Employer Identification No. ) 22102 ( Zip Code ) Title of Each Class Common Stock , $ 0.001 par value per share 6.375 % Series E Cumulative Term Preferred Stock , $ 0.001 par value per share 5.00 % Notes due 2026 , $ 25.00 par value per note 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 The Nasdaq Stock Market LLC The Nasdaq Stock Market LLC The Nasdaq Stock Market LLC 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 . 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 . □ П 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 Act ) . YES □ NO > The aggregate market value of the voting stock held by non - affiliates of the Registrant on September 30 , 2020 , based on the closing price on that date of $ 9.10 on the Nasdaq Global Select Market , was $ 294,365,821 . For the purposes of calculating this amount only , all directors and executive officers of the Registrant have been treated as affiliates . There were 33,205,023 shares of the Registrant's Common Stock , $ 0.001 par value , outstanding as of May 10 , 2021 . Documents Incorporated by Reference . Portions of the Registrant's definitive proxy statement relating to the Registrant's 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A are incorporated by reference into Part III of this Annual