Main Street Investor Presentation

Historical Monthly Dividends, Net Asset Value ("NAV") and Distributable Net Investment Income ("DNII") (1) Per Share MAIN's unique focus on equity investments in the Lower Middle Market provides the opportunity for significant NAV per share growth MAIN's efficient operating structure provides significant operating leverage, greater dividends and greater overall returns for our shareholders DNII and Dividends Per Share $0.80 I Recessionary $0.70 T Period $0.60 T $0.50 $0.40 $0.30 $0.20 T MAINST CAPITAL CORPORATION 2007 2009 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 $26.00 $24.00 $22.00 $20.00 $18.00 $16.00 $14.00 $12.00 $10.00 $0.00 Monthly Dividends -DNII per share ( NAV per share • In addition to monthly dividends above, $4.04 per share of supplemental dividends have been paid since 2013 ⚫ Annual return on equity averaging approximately 12.5% from 2010 through the second quarter of 2020 (1) See Non-GAAP Information included on page 47 of this presentation. Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 8 NAV Per Share

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