GLAD Gladstone Capital Corporation

Item 1.01. Entry into a Material Definitive Agreement.

Fourth Supplemental Indenture

On November 4, 2021, in connection with a previously announced private placement, Gladstone Capital Corporation (the “Company”) and U.S. Bank National Association, as trustee (the “Trustee”), entered into a Fourth Supplemental Indenture (the “Fourth Supplemental Indenture”) to the Indenture, dated November 6, 2018, between the Company and the Trustee (together with the Fourth Supplemental Indenture, the “Indenture”). The Fourth Supplemental Indenture relates to the Company’s issuance, offer and sale of $50 million aggregate principal amount of its 3.75% Notes due 2027 (the “Notes”).

The Notes will mature on May 1, 2027, unless previously redeemed or repurchased in accordance with their terms. The interest rate of the Notes is 3.75% per year and will be paid semi-annually in arrears on May 1 and November 1 of each year, commencing May 1, 2022. The Notes are the Company’s direct unsecured obligations and rank pari passu with the Company’s existing and future unsecured, unsubordinated indebtedness, including the Company’s 5.125% Notes due 2026; senior to any series of preferred stock that the Company may issue in the future; senior to any of the Company’s future indebtedness that expressly provides it is subordinated to the Notes; effectively subordinated to all of the Company’s existing and future secured indebtedness (including indebtedness that is initially unsecured to which the Company subsequently grants security), to the extent of the value of the assets securing such indebtedness; and structurally subordinated to all existing and future indebtedness and other obligations of any of the Company’s existing or future subsidiaries, including, without limitation, borrowings under the Company’s credit facility.

The Notes may be redeemed in whole or in part at any time or from time to time at the Company’s option, at a redemption price (as determined by the Company) equal to the greater of the following amounts, plus, in each case, accrued and unpaid interest to, but excluding, the redemption date: (1) 100% of the principal amount of the Notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest (exclusive of accrued and unpaid interest to the date of redemption) on the Notes to be redeemed, discounted to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) using the applicable Treasury Rate (as defined in the Fourth Supplemental Indenture) plus 50 basis points; provided, however, that if the Company redeems any Notes on or after February 1, 2027 (the date falling three months prior to the maturity date of the Notes), the redemption price for the Notes will be equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the date of redemption. In addition, if a Change of Control Repurchase Event (as defined in the Fourth Supplemental Indenture) occurs in respect of the Company, holders of the Notes may require the Company to repurchase for cash all or part of their Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the repurchase date.

The Indenture contains certain covenants, including covenants requiring the Company to comply with Section 18(a)(1)(A) as modified by Section 61(a)(2) of the Investment Company Act of 1940, as amended (the “Investment Company Act”), or any successor provisions, to comply with Section 18(a)(1)(B) as modified by Section 61(a)(2) of

the Investment Company Act, or any successor provisions but giving effect to any exemptive relief granted by the Securities and Exchange Commission (the “SEC”) to another business development company and upon which the Company may reasonably rely (or to the Company if the Company determines to seek such similar no-action or other relief), and to provide financial information to the holders of the Notes and the Trustee if the Company should no longer be subject to the reporting requirements under the Securities Exchange Act of 1934, as amended. These covenants are subject to important limitations and exceptions that are set forth in the Indenture.

The Notes were sold to the several initial purchasers in a private placement in reliance on Section 4(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”), and for the initial resale by the Initial Purchasers to qualified institutional buyers in transactions exempt from registration under the Securities Act pursuant to Rule 144A thereunder. The Notes will not be registered under the Securities Act and may not be offered or sold in the United States absent registration or an applicable exemption from registration. The transaction closed on November 4, 2021.

The Company intends to use the net proceeds from the offering to repay a portion of the amount outstanding under its credit facility, to fund new investment opportunities and for other general corporate purposes.

The description above is only a summary of the material provisions of the Fourth Supplemental Indenture and the Notes and is qualified in its entirety by reference to the Fourth Supplemental Indenture and the Notes, respectively, each filed as exhibits to this Current Report on Form 8-K and incorporated by reference herein.

Registration Rights Agreement

In connection with the offering, the Company entered into a Registration Rights Agreement, dated as of November 4, 2021 (the “Registration Rights Agreement”), with Raymond James & Associates, Inc., as representative of the several initial purchasers. Pursuant to the Registration Rights Agreement, the Company is obligated to file with the Securities and Exchange Commission a registration statement with respect to an offer to exchange the Notes for a new issue of debt securities registered under the Securities Act with terms substantially identical to those of the Notes (except for provisions relating to transfer restrictions and payment of additional interest) and to use its commercially reasonable efforts to consummate such exchange offer on the earliest practicable date after the registration statement has been declared effective but in no event later than 365 days after the initial issuance of the Notes. If the Company fails to satisfy its registration obligations under the Registration Rights Agreement, it will be required to pay additional interest to the holders of the Notes.

The description above is only a summary of the material provisions of the Registration Rights Agreement and is qualified in its entirety by reference to the Registration Rights Agreement, filed as an exhibit to this Current Report on Form 8-K and incorporated by reference herein.