Main Street Investor Presentation

MAINST CAPITAL CORPORATION MAIN Strategy Produces Differentiated Returns Enhanced Value Proposition - Three Ways to Win are Better Than One 1. Sustain and Grow Dividends Efficient operating structure provides operating leverage to grow distributable net investment income, and dividends paid, as investment portfolio and total investment income grow 86% increase in monthly dividends from $0.33 per share paid in Q4 2007 to declared dividends of $0.615 per share for Q4 2020 Never decreased regular monthly dividends (including through 2008/2009 recession) Paid or declared $29.600 per share in total dividends since October 2007 IPO at $15.00 per share ($25.560 per share in regular dividends and $4.040 per share in supplemental dividends) Multi-faceted investment strategy supports growth of dividends over various cycles and markets 2. Meaningfully Grow Net Asset Value ("NAV") Per Share $12.85 at December 31, 2007 to $20.85 at June 30, 2020-62% growth; CAGR of 3.9% Represents incremental economic return to investors beyond dividends MAIN's debt-focused peers (which comprises most BDCs) cannot generate NAV per share growth through the cycles Unrealized appreciation is a good proxy for future dividend growth without the need for additional capital through growing portfolio dividend income and harvested realized gains from equity investments Ability to grow NAV per share provides opportunity for MAIN stock share price appreciation and additional shareholder returns 3. Supplement Growth in Distributable Net Investment Income with Periodic Realized Gains LMM equity component of investment strategy provides opportunity for meaningful realized gains (analogous to PIK income on debt investments from cash flow perspective, but more tax efficient and without cap on upside) Realized gains validate the quality of MAIN's unrealized appreciation Realized gains can be paid to shareholders as dividends or retained for future reinvestment due to MAIN's unique tax structure Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 7

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