Main Street Capital Investor Day Presentation Deck

Match Funding with Investment Assets (1) MAIN maintains a capital structure that is designed to match our capital funding with our investment assets The term of our capital sources is matched with the expected hold period of our portfolio investments (% of total) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Long-term / Moderate-term Capital H Permanent Capital MAIN'S Capital Investments at FMV Moderate-term / partially illiquid Investments Long-term / illiquid Investments MAIN ST ■MAIN Equity SBIC Debentures 5-Year Notes 3-Year Notes ■Credit Facilities (2) (1) As of March 31, 2023; Investment Assets exclude investments in our Other Portfolio, Short-term Portfolio and MSC Adviser I, LLC (2) Outstanding funded balance only; excludes the unfunded capacity from MAIN's Credit Facilities Main Street Capital Corporation NYSE: MAIN CAPITAL CORPORATION Investments at Cost Equity Investments LMM Debt Investments PL Debt Investments MM Debt Investments mainstcapital.com

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