Main Street Investor Presentation

MAINST CAPITAL CORPORATION LMM Investment Portfolio LMM Investment Portfolio consists of a diversified mix of secured debt and lower cost basis equity investments 69 portfolio companies/$1,188.0 million in fair value • 49% of total investment portfolio at fair value Debt yielding 11.6% (1) (65% of LMM portfolio at cost) + • 98% of debt investments have first lien position 65% of debt investments earn fixed-rate interest Approximately 780 basis point net cash interest margin vs "matched" fixed interest rate on SBIC debentures Equity in 99% of LMM portfolio companies representing 41% average ownership position (35% of LMM portfolio at cost) Opportunity for fair value appreciation, capital gains and cash dividend income • 62% of LMM companies (2) with direct equity investment are currently paying dividends Fair value appreciation of equity investments supports Net Asset Value per share growth Lower entry multiple valuations, lower cost basis $155.7 million, or $2.37 per share, of cumulative pre-tax net unrealized appreciation at June 30, 2020 (1) Weighted-average effective yield includes amortization of deferred debt origination fees and accretion of original issue discount, but excludes fees payable upon repayment of the debt instruments and any debt investments on non-accrual status (2) Includes the LMM companies which (a) MAIN is invested in direct equity and (b) are treated as flow-through entities for tax purposes; based upon dividend income for the trailing twelve month period ended June 30, 2020 Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 22

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