Main Street Capital Investor Presentation Deck

MAIN Corporate Data Please visit our website at www.mainstcapital.com for additional information Board of Directors Executive Officers Research Coverage Vincent D. Foster Dwayne L. Hyzak Chairman of the Board Chief Executive Officer Vilas Abraham & Marissa Lobo UBS (212) 713-3241 (212) 713-3922 Main Street Capital Corporation Board of Directors Quanta Services, Inc. J. Kevin Griffin Chief Strategy Officer MaineHealth Dwayne L. Hyzak CEO Main Street Capital Corporation John E. Jackson President & CEO CSI Compressco LP Brian E. Lane CEO & President Comfort Systems USA Dunia A. Shive Board of Directors DallasNews Corporation, Kimberly-Clark Corporation and Trinity Industries, Inc. Stephen B. Solcher Retired CFO BMC Software David L. Magdol President & Chief Investment Officer Jesse E. Morris EVP, Chief Financial Officer & Chief Operating Officer Jason B. Beauvais EVP, General Counsel, Secretary & Chief Compliance Officer Nicholas T. Meserve Managing Director Ryan R. Nelson Vice President & Chief Accounting Officer Main Street Capital Corporation Robert J. Dodd Raymond James (901) 579-4560 Mark Hughes Truist Securities (404) 926-5607 Kenneth S. Lee RBC Capital Markets (212) 905-5995 Mitchel Penn Oppenheimer & Co (212) 667-7136 Bryce Rowe B. Riley Financial (703) 312-1820 Erik Zwick Hovde Group (617) 510-1239 Corporate Headquarters 1300 Post Oak Blvd, 8th Floor Houston, TX 77056 Tel: (713) 350-6000 Fax: (713) 350-6042 Independent Registered Public Accounting Firm Grant Thornton, LLP Houston, TX Corporate Counsel Dechert LLP Washington, D.C. Securities Listing Common Stock - NYSE: MAIN Transfer Agent American Stock Transfer & Trust Co. Tel: (800) 937-5449 www.astfinancial.com NYSE: MAIN MAINST CAPITAL CORPORATION Investor Relation Contacts Dwayne L. Hyzak Chief Executive Officer Jesse E. Morris EVP, Chief Financial Officer & Chief Operating Officer Tel: (713) 350-6000 Ken Dennard Zach Vaughan Dennard Lascar Investor Relations Tel: (713) 529-6600 Management Executive Committee Dwayne L. Hyzak, Chief Executive Officer David L. Magdol, President & Chief Investment Officer Jesse E. Morris, EVP, Chief Financial Officer & Chief Operating Officer Jason B. Beauvais, EVP, General Counsel, Secretary & Chief Compliance Officer Investment Committee Dwayne L. Hyzak, Chief Executive Officer David L. Magdol, President & Chief Investment Officer Vincent D. Foster, Chairman of the Board mainstcapital.com Page 49

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