Main Street Investor Presentation

Term and Total Interest Coupon of Existing LMM Debt Investments Original Term < 5 years 95% 4% 1% > 5 years 5 years Total Interest Coupon (1) N/A - Floating Interest Rate (Wtd. Avg. of 10.6%) MAINST CAPITAL CORPORATION 39% 11% 14% Current Interest <10% Current Interest 1% 7% 6% 10% Current Interest 11% Current Interest 34% 13% Current Interest 12% Current Interest Debt Investments generally have a 5-Year Original Term and -2.7 Year Weighted-Average Remaining Duration; Weighted-Average Effective Yield of 11.6% on Debt Portfolio (1) Interest coupon excludes amortization of deferred upfront fees, original issue discount, exit fees and any debt investments on non-accrual status (2) Floating interest rates generally include contractual minimum "floor" rates; Interest rate of 10.6% is based on weighted-average principal balance of floating rate debt investments as of June 30, 2020 Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 27

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