UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 29, 2017 (August 24, 2017)

Gladstone Capital Corporation

(Exact name of registrant as specified in its charter)

(703) 287-5800

(Registrant’s telephone number, including area code)

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 1.01. Entry into a Material Definitive Agreement.

On August 24, 2017 Gladstone Capital Corporation (the “Company”), through its wholly-owned subsidiary Gladstone Business Loan, LLC, entered into Amendment No. 3 (the “Amendment”) to its Fifth Amended and Restated Credit Agreement, with KeyBank National Association (“KeyBank”), as administrative agent, swingline lender, managing agent and lead arranger, Gladstone Management Corporation, the Company’s Adviser, as servicer, and certain other lenders party thereto (together with the Amendment, the “Credit Facility”).

Primarily, the Amendment adjusts the calculation of the borrowing base of the Credit Facility and clarifies the application of excess concentrations. The Amendment also, among other items, increases the excess concentration limits for PIK loans and updates the commitment amounts for the Lenders. As of August 23, 2017, prior to the closing of the Amendment, $76.5 million of borrowings were outstanding under the Credit Facility.

The foregoing summary of the Amendment is not complete and is qualified in its entirety by reference to the Amendment, which is filed as Exhibit 10.1 to this Current Report on Form 8-K and incorporated by reference into this Item 1.01.

Item 2.03. Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

The information set forth under Item 1.01 is hereby incorporated by reference into this Item 2.03.

Item 9.01. Financial Statements and Exhibits

(c) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

EXHIBIT INDEX