Main Street Capital Investor Presentation Deck

MAIN is a Principal Investor in Private Debt and Equity Focus on unique Lower Middle Market debt and equity investment strategy, Asset Management Business and internally managed operating structure differentiates MAIN from other investment firms ● Internally-managed Business Development Company (BDC) IPO in 2007 ● ● Approximately $6.6 billion in capital under management(¹) Approximately $5.0 billion internally at MAIN(¹) Over $1.6 billion as the investment adviser to external parties(¹) Primarily invests in the under-served Lower Middle Market (LMM) ● - ● MAINST CAPITAL CORPORATION Proprietary debt investments in privately held companies typically owned by private equity sponsors (Private Loans) Originated directly by MAIN or through strategic relationships with other investment funds First lien, senior secured debt investments Companies consistent with size of the companies in MAIN's LMM and Middle Market investment strategies Targets companies with revenue between $10 million - $150 million; EBITDA between $3 million $20 million Provides single source solutions, including a combination of first lien, senior secured debt and equity financing Debt investments in Middle Market companies First lien, senior secured and/or rated debt investments Larger companies than LMM investment strategy Attractive asset management advisory business Significant management ownership / investment in MAIN Headquartered in Houston, Texas (1) Capital under management includes undrawn portion of debt capital as of March 31, 2023 Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 4

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