On May 28, 2024, Main Street Capital Corporation entered into an underwriting agreement (the ?Underwriting Agreement?) by and among Main Street and Truist Securities Inc., as representative of the underwriters named in Schedule A thereto, in connection with the issuance and sale of $300 million in aggregate principal amount (the ?Offering?) of Main Street?s 6.50% notes due 2027 (the ?Notes?). The Offering is expected to close on June 4, 2024, subject to customary closing conditions. The Offering is being made pursuant to Main Street?s effective shelf registration statement on Form N-2 (Registration No.

333-263258) previously filed with the SEC, as supplemented by a preliminary prospectus supplement dated May 28, 2024 and a final prospectus supplement dated May 28, 2024. The net proceeds to be received by Main Street are estimated to be approximately $297.4 million, after deducting the underwriting discounts and estimated Offering expenses payable by Main Street. Main Street intends to initially use the net proceeds from the Offering to repay outstanding indebtedness, including amounts outstanding under its credit facilities.

On May 26, 2024, Main Street entered into the Fifth Amendment to Third Amended and Restated Credit Agreement dated as of June 5, 2018, as amended (the ?Fifth Amendment?), among Main Street, as borrower, and, solely with respect to Section 8 thereof, Main Street Capital Partners, LLC, Main Street Equity Interests Inc., Main Street CA Lending, LLC and MS International Holdings Inc., as guarantors, Truist Bank, as administrative agent and lender, and the other lenders party thereto, which, among other things, permits the issuance of the Notes. The foregoing description of the Underwriting Agreement and the Fifth Amendment does not purport to be complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement, which is filed with this Current Report on Form 8-K as Exhibit 1.1 and incorporated herein by reference and the full text of the Fifth Amendment, which is filed with this Current Report on Form 8-K as Exhibit 99.1 and is incorporated herein by reference.