Main Street Capital Investor Day Presentation Deck

MAIN's Return on Equity Compared to Industry Top GAAP ROE's Under RJ Coverage MAIN is the top performer on the key overall total return performance metric (GAAP Return on Equity, or ROE) MAIN'S GAAP ROE of 13.0% ranks #1 in the Raymond James' (RJ) coverage group ● ● Significant outperformance (-20% vs #2 ranked BDC) vs. BDCs with IPO dates in or before 2007 #1 overall for all BDCs despite MAIN experiencing impacts of the 2008/2009 Great Recession MAIN's Implied Credit Gains of 2.5% is well above the Industry average of an Implied Credit Loss of (1.3%) 14% 12% 10% 8% 6% 4% 2% 0% -2% Ticker Top 10% Top Quartile Middle Quartile Bottom Quartile Chart 15 - Historic Average GAAP ROE 4% 2% 10% MAIN FDUS TSLX W. Average -2% -4% -16% -8% -10% -12% Median ARCC BBDC W. Average Median BCSF ARCC BBDC BXSL BCSF ............... .............. LI Im dali Source: FactSet and Raymond James research. Chart 16 - Implied Credit Gains (Losses) GAAP ROE CCAP BXSL CGBD CCAP 13.0% 12.3% 12.0% 12.0% 9.5% 8.1% 6.6% CION CGBD CSWC CION FDUS FDUS CSWC FSK IPO Date 4Q 2007 2Q 2011 1Q 2014 FSK GBDC GBDC GLAD GSBD S ICMB GLAD MAIN ICMB GSBD MFIC MFIC MAIN Top 10% Top Quartile Middle Quartile Bottom Quartile OCSL NMFC OCSL NMFC Top GAAP ROE's Under RJ Coverage IPO Dates 2007 or prior Ticker GAAP ROE ORCC MAIN ARCC PSEC PELT ORCC PNNT PFLT PSEC PSEC PNNT SAR SAR SCM SCM SLRC TCPC SLRC TCPC MAINST CAPITAL CORPORATION 13.0% 11.0% 9.1% 13.0% 10.0% 6.9% 4.4% TSLX TSLX WHF WHF IPO Date 4Q 2007 4Q 2004 3Q 2004 Source: FactSet and Raymond James research. Note: Key Performance Metrics sourced from Raymond James' (RJ) June 2, 2023 Specialty Finance/ Business Development Companies 1Q23 ROE Quarterly Analysis; Select pages included in Appendix A Main Street Capital Corporation NYSE: MAIN mainstcapital.com

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