UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 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 7, 2023

New Mountain Finance Corporation

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (212) 720-0300

None

(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 (see General Instruction A.2. below):

Securities registered pursuant to Section 12(b) of the Act:

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. ¨

Fee Waiver Letter

On August 7, 2023, New Mountain Finance Advisers BDC, L.L.C., a Delaware limited liability company (the “Adviser”), delivered a Fee Waiver Letter (the “Fee Waiver Letter”) to New Mountain Finance Corporation (the “Company”) for the purpose of extending the term of that certain fee waiver letter dated May 4, 2021, as amended by that certain fee waiver letter amendment dated November 2, 2021 (the “Initial Fee Waiver Letter”), provided to the Company by the Adviser. Pursuant to the Fee Waiver Letter, the Adviser extended the term of the Initial Fee Waiver Letter to be effective through the quarter ending December 31, 2024, rather than the quarter ending December 31, 2023.

Pursuant to the Fee Waiver Letter, the Adviser agreed to voluntarily reduce the Base Management Fee (as defined in the Investment Advisory and Management Agreement, dated as of May 8, 2014, and as amended by Amendment No. 1 thereto on November 1, 2021, by and between the Company and the Adviser (the “Management Agreement”)) payable to the Adviser by the Company under the Management Agreement. Effective as of and for the quarter ended March 31, 2021 (the “Effective Date”) through the quarter ending December 31, 2024 (the “Termination Date”), the Adviser has agreed to calculate the Base Management Fee as set forth in the Fee Waiver Letter, and to waive such portion of the Base Management Fee payable under the Management Agreement that is in excess of the Reduced Base Management Fee.

Pursuant to the Management Agreement, the Adviser, for its services to the Company, is entitled to receive a Base Management Fee from the Company calculated at an annual rate of 1.4% of the Company’s gross assets, as presented in the Company’s consolidated financial statements prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), less cash and cash equivalents. The Base Management Fee is payable quarterly in arrears, and is calculated based on the average value of the Company’s gross assets at the end of that quarter and the most recent previously completed calendar quarter, and appropriately adjusted on a pro rata basis for any equity capital raised or repurchased during the current calendar quarter.

Under the Fee Waiver Letter, as of the Effective Date and through the Termination Date, the Reduced Base Management Fee will be calculated at an annual rate of 1.25% of the Company’s gross assets, as presented in the Company’s consolidated financial statements prepared in conformity with GAAP (the “Reduced Base Management Fee”). The Reduced Base Management Fee will be payable quarterly in arrears, and will be calculated based on the average value of the Company’s gross assets at the end of that quarter and the most recent previously completed calendar quarter, and appropriately adjusted on a pro rata basis for any equity capital raised or repurchased during the current calendar quarter.

The description above is qualified in its entirety by reference to the copy of the Fee Waiver Letter, which is filed as Exhibit 10.1 to this current report on Form 8-K and is incorporated herein by reference thereto.

Exhibit No.

SIGNATURE

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.

Date: August 9, 2023