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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 to Portman Ridge Finance Corporation ( Exact name of Registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) Commission File No. 814-00735 Title of each class Common Stock , par value $ 0.01 per share 6.125 % Notes due 2022 Large accelerated filer Emerging Growth Company 650 Madison Avenue , 23rd Floor New York , New York 10022 ( Address of principal executive offices ) ( 212 ) 891-2880 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) PTMN KCAPL 20-5951150 ( I.R.S. Employer Identification Number ) 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 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 Global Select Market The NASDAQ Global Select 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 , " " non - accelerated filer , " " smaller reporting company " and " emerging growth company " in Rule 12b - 2 of the Exchange Act : Accelerated filer Non - accelerated filer X 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 7 ( a ) ( 2 ) ( B ) of the Securities 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 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 and non - voting common stock held by non - affiliates of the registrant as of June 30 , 2020 was approximately $ 46,617,065 based upon a closing price of $ 1.10 reported for such date by The NASDAQ Global Select Market . This determination of affiliate status is not necessarily a conclusive determination for other purposes . The number of outstanding shares of common stock of the registrant as of March 5 , 2021 was 75,195,141 .