Main Street Investor Presentation

Private Loan Investment Portfolio MAINST CAPITAL CORPORATION Private Loan Investment Portfolio provides a diversified mix of investments and sources of income to complement the LMM Investment Portfolio 64 investments/ $653.8 million in fair value 27% of total investment portfolio at fair value Average investment size of $11.7 million(1) (less than 1% of total portfolio) Investments in secured debt instruments • 92% of Private Loan portfolio is secured debt • 95% of Private Loan debt portfolio is first lien term debt Debt yielding 8.7% (2) 91% of Private Loan debt investments bear interest at floating rates (3), providing matching with MAIN's floating rate credit facility Approximately 575 basis point net cash interest margin vs "matched" floating rate on the MAIN credit facility (1) As of June 30, 2020; based on cost (2) 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 (3) 87% of floating interest rates on Private Loan debt investments are subject to contractual minimum "floor" rates Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 28

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