Exhibit (d)(8)

SECOND SUPPLEMENTAL INDENTURE

between

NEW MOUNTAIN FINANCE CORPORATION

and

U.S. BANK NATIONAL ASSOCIATION,

as Trustee

Dated as of September 25, 2018

THIS SECOND SUPPLEMENTAL INDENTURE (this “Second Supplemental Indenture”), dated as of September 25, 2018, is between NEW MOUNTAIN FINANCE CORPORATION, a Delaware corporation (the “Company”), and U.S. Bank National Association, as trustee (the “Trustee”). All capitalized terms used herein shall have the meaning set forth in the Base Indenture (as defined below).

RECITALS OF THE COMPANY

The Company and the Trustee executed and delivered an Indenture, dated as of August 20, 2018 (the “Base Indenture” and, as supplemented by this Second Supplemental Indenture, the “Indenture”), to provide, among other things, for the issuance, from time to time, of the Company’s unsecured debt securities, in an unlimited aggregate principal amount (the “Securities”), in one or more series to be established by the Company under, and authenticated and delivered as provided in, the Base Indenture.

The Company desires to issue and sell up to $50,000,000 aggregate principal amount (or up to $57,500,000 aggregate principal amount if the underwriters’ overallotment option to purchase additional Notes is exercised in full) of the Company’s 5.75% Notes due 2023 (the “Notes”).

The Company previously entered into the First Supplemental Indenture, dated as of August 20, 2018 (the “First Supplemental Indenture”), which supplemented the Base Indenture. The First Supplemental Indenture is not applicable to the Notes.

Sections 901(4) and 901(6) of the Base Indenture provide that without the consent of Holders of the Securities of any series issued under the Indenture, the Company, when authorized by or pursuant to a Board Resolution, and the Trustee, at any time and from time to time, may enter into one or more indentures supplemental to the Base Indenture to (i) change or eliminate any of the provisions of the Indenture when there is no Security Outstanding of any series created prior to the execution of the supplemental indenture that is entitled to the benefit of such provision and (ii) establish the form or terms of Securities of any series as permitted by Section 201 and Section 301 of the Base Indenture.

The Company desires to establish the form and terms of the Notes and to modify, alter, supplement and change certain provisions of the Base Indenture for the benefit of the Holders of the Notes (except as may be provided in a future supplemental indenture to the Indenture (each, a “Future Supplemental Indenture”)).

The Company has duly authorized the execution and delivery of this Second Supplemental Indenture to provide for the issuance of the Notes and all acts and things necessary to make this Second Supplemental Indenture a valid, binding, and legal obligation of the Company and to constitute a valid agreement of the Company, in accordance with its terms, have been done and performed.

NOW, THEREFORE, for and in consideration of the premises and the purchase of the Notes by the Holders thereof, it is mutually agreed, for the equal and proportionate benefit of all Holders of the Notes, as follows:

ARTICLE I

TERMS OF THE NOTES

Section 1.01. Terms of the Notes. The following terms relating to the Notes are hereby established:

(a) The Notes shall constitute a series of Senior Securities having the title “5.75% Notes due 2023.” The Notes shall bear a CUSIP number of 647551 209 and an ISIN number of US6475512090, as may be supplemented or replaced from time to time.

(b) The aggregate principal amount of the Notes that may be initially authenticated and delivered under the Indenture (except for Notes authenticated and delivered upon registration of, transfer of, or in exchange for, or in lieu of, other Notes pursuant to Sections 304, 305, 306, 906, 1107 or 1305 of the Base Indenture, and except for any Securities that, pursuant to Section 303 of the Base Indenture, are deemed never to have been authenticated and delivered under the Indenture) shall be $50,000,000 (or up to $57,500,000 aggregate principal amount if the underwriters’ overallotment option to purchase additional Notes is exercised in full). Under a Board Resolution, Officers’ Certificate pursuant to Board Resolutions or an indenture supplement, the Company may from time to time, without the consent of the Holders of Notes, issue additional Notes (in any such case “Additional Notes”) having the same ranking and the same interest rate, maturity and other terms as the Notes; provided that, if such Additional Notes are not fungible with the Notes (or any other tranche of Additional Notes) for U.S. federal income tax purposes, then such Additional Notes will have different CUSIP numbers from the Notes (and any such other tranche of Additional Notes). Any Additional Notes and the existing Notes will constitute a single series under the Indenture and all references to the relevant Notes herein shall include the Additional Notes unless the context otherwise requires.

(c) The entire outstanding principal of the Notes shall be payable on October 1, 2023, unless earlier redeemed or repurchased in accordance with the provisions of this Second Supplemental Indenture.

(d) The rate at which the Notes shall bear interest shall be 5.75% per annum. The date from which interest shall accrue on the Notes shall be September 25, 2018, or the most recent Interest Payment Date to which interest has been paid or provided for; the Interest Payment Dates for the Notes shall be January 1, April 1, July 1 and October 1 of each year, commencing January 1, 2019 (if an Interest Payment Date falls on a day that is not a Business Day, then the applicable interest payment will be made on the next succeeding Business Day and no additional interest will accrue as a result of such delayed payment); the initial interest period will be the period from and including September 25, 2018, to, but excluding, the initial Interest Payment Date, and the subsequent interest periods will be the periods from and including an Interest Payment Date to, but excluding, the next Interest Payment Date or the Stated Maturity, as the case may be; the interest so payable, and punctually paid or duly provided for, on any Interest Payment Date, will be paid to the Person in whose name the Note (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be December 15, March 15, June 15 or September 15 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Payment of principal of (and premium, if any, on) and any such interest on the Notes will be made at the office of the Trustee located at 111 Fillmore Avenue, St. Paul, MN 55107, Attention: New Mountain Finance Corporation (5.75% Notes Due 2023) or at such other address as designated by the Trustee, in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts; provided, however, that at the option of the Company payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register; provided, further, however, that, at the request of the registered Holder, the Company will pay the principal of (and premium, if any, on) and interest, if any, on the Notes by wire transfer of immediately available funds to an account at a bank in New York City, on the date when such amount is due and payable and as further set forth in Section 1001 of the Indenture; provided, further, however, that so long as the Notes are registered to Cede & Co., such payment will be made by wire transfer in accordance with the procedures established by The Depository Trust Company and the Trustee. Interest on the Notes will be computed on the basis of a 360-day year of twelve 30-day months.

(e) The Notes shall be initially issuable in global form (each such Note, a “Global Note”). The Global Notes and the Trustee’s certificate of authentication thereon shall be substantially in the form of Exhibit A to this Second Supplemental Indenture. Each Global Note shall represent the aggregate amount of the outstanding Notes as shall be specified therein and each shall provide that it shall represent the aggregate amount of outstanding Notes from time to time endorsed thereon and that the aggregate amount of outstanding Notes represented thereby may from time to time be reduced or increased, as appropriate, to reflect exchanges and redemptions. Any endorsement of a Global Note to reflect the amount of any increase or decrease in the amount of outstanding Notes represented thereby shall be made by the Trustee or the Security Registrar, in accordance with Sections 203 and 305 of the Base Indenture.

(f) The depositary for such Global Notes (the “Depositary”) shall be The Depository Trust Company, New York, New York. The Security Registrar with respect to the Global Notes shall be the Trustee.

(g) The Notes shall be defeasible pursuant to Section 1402 or Section 1403 of the Base Indenture. Covenant defeasance contained in Section 1403 of the Base Indenture shall apply to the covenants contained in Sections 1007, 1008, 1009 and 1010 of the Indenture.

(h) The Notes shall be redeemable pursuant to Section 1101 of the Base Indenture and as follows:

(i) The Notes will be redeemable in whole or in part at any time or from time to time, at the option of the Company, on or after October 1, 2020, at a Redemption Price equal to 100% of the outstanding principal amount thereof, plus accrued and unpaid interest payments otherwise payable for the then-current quarterly interest period accrued to, but excluding, the Redemption Date.

(ii) Notice of redemption shall be given in writing and mailed, first-class postage prepaid or by overnight courier guaranteeing next-day delivery, to each Holder of the Notes to be redeemed, not less than thirty (30) nor more than sixty (60) days prior to the Redemption Date, at the Holder’s address appearing in the Security Register. All notices of redemption shall contain the information set forth in Section 1104 of the Base Indenture.

(iii) Any exercise of the Company’s option to redeem the Notes will be done in compliance with the Indenture and the Investment Company Act, to the extent applicable.

(iv) If the Company elects to redeem only a portion of the Notes, the Trustee or, with respect to the Global Notes, the Depositary will determine the method for selecting the particular Notes to be redeemed, in accordance with Section 1103 of the Base Indenture and the Investment Company Act and the rules of any national securities exchange or quotation system on which the Notes are listed, in each case to the extent applicable.

(v) Unless the Company defaults in payment of the Redemption Price, on and after the Redemption Date, interest will cease to accrue on the Notes called for redemption hereunder.

(i) The Notes shall not be subject to any sinking fund pursuant to Section 1201 of the Base Indenture.

(j) The Notes shall be issuable in denominations of $25.00 and integral multiples of $25.00 in excess thereof.

(k) Holders of the Notes will not have the option to have the Notes repaid prior to the Stated Maturity.

(l) The Notes are hereby designated as “Senior Securities” under the Indenture.

ARTICLE II

DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

Section 2.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Article One of the Base Indenture shall be amended by adding the following defined terms to Section 101 in appropriate alphabetical sequence, as follows:

“Business Day” means any day, other than a Saturday, a Sunday or a day on which the Federal Reserve Bank of New York or the Trustee is authorized or required by law or executive order to close or be closed.

“Capital Leases” means, at any time, a lease with respect to which the lessee is required concurrently to recognize the acquisition of an asset and the incurrence of a liability in accordance with GAAP.

“Debt to Equity Ratio” means the ratio of (a) the aggregate amount of senior securities representing indebtedness of the Company and its Subsidiaries (including under the Notes), in each case as determined pursuant to the Investment Company Act, and any orders of the Commission issued to or with respect to Company thereunder, including any exemptive relief granted by the Commission with respect to the indebtedness of any SBIC Subsidiary to (b) Shareholders’ Equity at the last day of the immediately preceding fiscal quarter of the Company.

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and any statute successor thereto.

“GAAP” means generally accepted accounting principles as in effect from time to time in the United States of America.

“Governmental Authority” means

(a) the government of

(i) the United States of America or any state or other political subdivision thereof, or

(ii) any other jurisdiction in which the Company or any Subsidiary conducts all or any part of its business, or which asserts jurisdiction over any properties of the Company or any Subsidiary, or

(b) any entity exercising executive, legislative, judicial, regulatory or administrative functions of, or pertaining to, any such government.

“Guaranty” means, with respect to any Person, any obligation (except the endorsement in the ordinary course of business of negotiable instruments for deposit or collection) of such Person guaranteeing or in effect guaranteeing any indebtedness, dividend or other obligation of any other Person in any manner, whether directly or indirectly, including (without limitation) obligations incurred through an agreement, contingent or otherwise, by such Person:

(a) to purchase such indebtedness or obligation or any property constituting security therefor;

(b) to advance or supply funds (i) for the purchase or payment of such indebtedness or obligation, or (ii) to maintain any working capital or other balance sheet condition or any income statement condition of any other Person or otherwise to advance or make available funds for the purchase or payment of such indebtedness or obligation;

(c) to lease properties or to purchase properties or services primarily for the purpose of assuring the owner of such indebtedness or obligation of the ability of any other Person to make payment of the indebtedness or obligation; or

(d) otherwise to assure the owner of such indebtedness or obligation against loss in respect thereof.

In any computation of the indebtedness or other liabilities of the obligor under any Guaranty, the indebtedness or other obligations that are the subject of such Guaranty shall be assumed to be direct obligations of such obligor.

“Indebtedness” with respect to any Person means, at any time, without duplication,

(a) its liabilities for borrowed money and its redemption obligations in respect of mandatorily redeemable Preferred Stock;

(b) its liabilities for the deferred purchase price of property acquired by such Person (excluding accounts payable arising in the ordinary course of business but including all liabilities created or arising under any conditional sale or other title retention agreement with respect to any such property);

(c) (i) all liabilities appearing on its balance sheet in accordance with GAAP in respect of Capital Leases and (ii) all liabilities which would appear on its balance sheet in accordance with GAAP in respect of Synthetic Leases assuming such Synthetic Leases were accounted for as Capital Leases;

(d) all liabilities for borrowed money secured by any Lien with respect to any property owned by such Person (whether or not it has assumed or otherwise become liable for such liabilities);

(e) all its liabilities in respect of letters of credit or instruments serving a similar function issued or accepted for its account by banks and other financial institutions (whether or not representing obligations for borrowed money);

(f) the aggregate Swap Termination Value of all Swap Contracts of such Person; and

(g) any Guaranty of such Person with respect to liabilities of a type described in any of clauses (a) through (f) hereof.

Indebtedness of any Person shall include all obligations of such Person of the character described in clauses (a) through (g) to the extent such Person remains legally liable in respect thereof notwithstanding that any such obligation is deemed to be extinguished under GAAP.

“Investment Company Act” means the Investment Company Act of 1940, as amended, and the rules, regulations and interpretations promulgated thereunder, to the extent applicable, and any statute successor thereto.

“Lien” means, with respect to any Person, any mortgage, lien, pledge, charge, security interest or other encumbrance, or any interest or title of any vendor, lessor, lender or other secured party to or of such Person under any conditional sale or other title retention agreement or Capital Lease, upon or with respect to any property or asset of such Person (including in the case of stock, stockholder agreements, voting trust agreements and all similar arrangements).

“Permitted SBIC Guaranty” means a guarantee by the Company of Indebtedness of an SBIC Subsidiary on the SBA’s then applicable form, provided that the recourse to the Company thereunder is expressly limited only to periods after the occurrence of an event or condition that is an impermissible change in the control of such SBIC Subsidiary.

“Person” means an individual, partnership, corporation, limited liability company, association, trust, unincorporated organization, business entity or Governmental Authority.

“Preferred Stock” means any class of capital stock of a Person that is preferred over any other class of capital stock (or similar equity interests) of such Person as to the payment of dividends or the payment of any amount upon liquidation or dissolution of such Person.

“SBA” means the United States Small Business Administration.

“SBIC Equity Commitment” means a commitment by the Company to make one or more capital contributions to an SBIC Subsidiary.

“SBIC Subsidiary” means any direct or indirect Subsidiary (including such Subsidiary’s general partner or managing entity to the extent that the only material asset of such general partner or managing entity is its equity interest in the SBIC Subsidiary) of the Company licensed as a small business investment company under the Small Business Investment Act of 1958, as amended, (or that has applied for such a license and is actively pursuing the granting thereof by appropriate proceedings promptly instituted and diligently conducted) and which is designated by the Company (as provided below) as an SBIC Subsidiary, so long as (a) no portion of the Indebtedness or any other obligations (contingent or otherwise) of such Subsidiary: (i) is guaranteed by the Company or any Subsidiary (other than a Permitted SBIC Guaranty), (ii) is recourse to or obligates the Company or any Subsidiary in any way (other than in respect of any SBIC Equity Commitment or Permitted SBIC Guaranty), or (iii) subjects any property of the Company or any Subsidiary, directly or indirectly, contingently or otherwise, to the satisfaction thereof, other than equity interests in any SBIC Subsidiary pledged to secure such Indebtedness, and (b) none of the Company or any Subsidiary has any obligation to maintain or preserve such Subsidiary’s financial condition or cause such entity to achieve certain levels of operating results. Any such designation by the Company shall be effected pursuant to a certificate of a Senior Financial Officer delivered to the Trustee, which certificate shall include a statement to the effect that, to the best of such officer’s knowledge, such designation complied with the foregoing conditions.

“Secured Debt” means Indebtedness of the Company and its Subsidiaries that are consolidated with the Company for purposes of GAAP (excluding any Indebtedness of any of the Company’s Subsidiaries which are SBIC Subsidiaries) outstanding at any time that is secured in any manner by any Lien on assets of the Company or any such Subsidiaries.

“Secured Debt Ratio” means the ratio of (a) Secured Debt to (b) the aggregate amount of Indebtedness of the Company and its Subsidiaries that are consolidated with the Company for purposes of GAAP (including Indebtedness under the Notes and excluding any Indebtedness of any of the Company’s Subsidiaries which are SBIC Subsidiaries).

“Senior Financial Officer” means the chief financial officer, principal accounting officer, treasurer or comptroller of the Company.

“Shareholders Equity” means at any date, the amount determined on a consolidated basis, without duplication, in accordance with GAAP, of shareholders’ equity or net assets, as applicable, for the Company and its Subsidiaries at such date.

“Subsidiary” means, as to any Person, any other Person in which such first Person or one or more of its Subsidiaries or such first Person and one or more of its Subsidiaries owns sufficient equity or voting interests to enable it or them (as a group) ordinarily, in the absence of contingencies, to elect a majority of the directors (or Persons performing similar functions) of such second Person, and any partnership or joint venture if more than a 50% interest in the profits or capital thereof is owned by such first Person or one or more of its Subsidiaries or such first Person and one or more of its Subsidiaries (unless such partnership or joint venture can and does ordinarily take major business actions without the prior approval of such Person or one or more of its Subsidiaries). Unless the context otherwise clearly requires, any reference to a “Subsidiary” is a reference to a Subsidiary of the Company.

“Swap Contract” means (a) any and all interest rate swap transactions, basis swap transactions, basis swaps, credit derivative transactions, forward rate transactions, commodity swaps, commodity options, forward commodity contracts, equity or equity index swaps or options, bond or bond price or bond index swaps or options or forward foreign exchange transactions, cap transactions, floor transactions, currency options, spot contracts or any other similar transactions or any of the foregoing (including, without limitation, any options to enter into any of the foregoing), and (b) any and all transactions of any kind, and the related confirmations, which are subject to the terms and conditions of, or governed by, any form of master agreement published by the International Swaps and Derivatives Association, Inc. or any International Foreign Exchange Master Agreement.

“Swap Termination Value” means, in respect of any one or more Swap Contracts, after taking into account the effect of any legally enforceable netting agreement relating to such Swap Contracts, (a) for any date on or after the date such Swap Contracts have been closed out and termination value(s) determined in accordance therewith, such

termination value(s), and (b) for any date prior to the date referenced in clause (a), the amounts(s) determined as the mark-to-market values(s) for such Swap Contracts, as determined based upon one or more mid-market or other readily available quotations provided by any recognized dealer in such Swap Contracts.

“Synthetic Lease” means, at any time, any lease (including leases that may be terminated by the lessee at any time) of any property (a) that is accounted for as an operating lease under GAAP and (b) in respect of which the lessee retains or obtains ownership of the property so leased for U.S. federal income tax purposes, other than any such lease under which such Person is the lessor.

Section 2.02. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Section 104 of the Base Indenture shall be amended by replacing clause (d) thereof with the following:

“(d) If the Company shall solicit from the Holders of Registered Securities any request, demand, authorization, direction, notice, consent, waiver or other Act, the Company may, at its option, in or pursuant to a Board Resolution, fix in advance a record date for the determination of Holders entitled to give such request, demand, authorization, direction, notice, consent, waiver or other Act, but the Company shall have no obligation to do so. Such record date shall be the record date specified in or pursuant to such Board Resolution, which date shall be a date not earlier than the date 30 days prior to the first solicitation of Holders generally in connection therewith and not later than the date such solicitation is completed. If such a record date is fixed, such request, demand, authorization, direction, notice, consent, waiver or other Act may be given before or after such record date, but only the Holders of record at the close of business on such record date shall be deemed to be Holders for the purposes of determining whether Holders of the requisite proportion of Outstanding Securities have authorized or agreed or consented to such request, demand, authorization, direction, notice, consent, waiver or other Act, and for that purpose the Outstanding Securities shall be computed as of such record date; provided that no such authorization, agreement or consent by the Holders on such record date shall be deemed effective unless it shall become effective pursuant to the provisions of this Indenture not later than eleven months after the record date.”

ARTICLE III

REMEDIES

Section 3.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Section 502 of the Base Indenture shall be amended by replacing the first paragraph thereof with the following:

“If an Event of Default (other than an Event of Default referred to in clause (5) or (6) of Section 501) with respect to Securities of any series at the time Outstanding occurs and is continuing, then and in every such case the Trustee or the Holders of not less than 25% in principal amount of the Outstanding Securities of that series may (and the Trustee shall at the request of such Holders) declare the principal (or, if any Securities are Original Issue Discount Securities or Indexed Securities, such portion of the principal as may be specified in the terms thereof) of all the Securities of that series to be due and payable immediately, by a notice in writing to the Company (and to the Trustee if given by the Holders), and upon any such declaration such principal or specified portion thereof shall become immediately due and payable. If an Event of Default referred to in clause (5) or (6) of Section 501 with respect to the Company has occurred, the entire principal amount of all of the Notes shall automatically become due and immediately payable.”

ARTICLE IV

COVENANTS

Section 4.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Article Ten of the Base Indenture shall be amended by adding the following new Sections 1007, 1008, 1009 and 1010 thereto, each as set forth below:

“Section 1007. Section 18(a)(1)(A) of the Investment Company Act.

The Company hereby agrees that for the period of time during which Notes are Outstanding, the Company will not violate Section 18(a)(1)(A) as modified by such provisions of Section 61(a) of the Investment Company Act as may be applicable to the Company from time to time or any successor provisions thereto, whether or not the Company continues to be subject to such provisions of the Investment Company Act, but giving effect, in either case, to any exemptive relief granted to the Company by the Commission.”

“Section 1008. Debt to Equity Ratio.

Immediately after the issuance of any senior security representing indebtedness (as determined pursuant to the Investment Company Act), and after giving pro forma effect thereto and the application of the proceeds thereof, the Company shall not permit the Debt to Equity Ratio to be greater than 1.65 to 1.00.”

“Section 1009. Maximum Secured Debt.

The Company shall not permit the Secured Debt Ratio at any time to exceed 0.70 to 1.00.”

“Section 1010. Commission Reports and Reports to Holders.

If, at any time, the Company is not subject to the reporting requirements of Sections 13 or 15(d) of the Exchange Act to file any periodic reports with the Commission, the Company agrees to furnish to the Holders of the Notes and the Trustee for the period of time during which the Notes are Outstanding: (i) within 90 days after the end of the each fiscal year of the Company, audited annual consolidated financial statements of the Company and (ii) within 45 days after the end of each fiscal quarter of the Company (other than the Company’s fourth fiscal quarter), unaudited interim consolidated financial statements of the Company. All such financial statements shall be prepared, in all material respects, in accordance with GAAP.”

ARTICLE V

REDEMPTION OF SECURITIES

Section 5.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Section 1103 of the Base Indenture shall be amended by replacing the first paragraph thereof with the following:

“If less than all the Securities of any series issued on the same day with the same terms are to be redeemed, the particular Securities to be redeemed shall be selected by the Trustee, or by the Depositary in the case of global Securities, in compliance with the requirements of DTC, from the Outstanding Securities of such series issued on such date with the same terms not previously called for redemption, in compliance with the requirements of the principal national securities exchange on which the Securities are listed (if the Securities are listed on any national securities exchange), or if the Securities are not held through DTC or listed on any national securities exchange, or DTC prescribed no method of selection, by such method as the Trustee shall deem fair and appropriate and subject to and otherwise in accordance with the procedures of the applicable Depositary; provided that such method complies with the rules of any national securities exchange or quotation system on which the Securities are listed, and may provide for the selection for redemption of portions (equal to the minimum authorized denomination for Securities of that series or any integral multiple thereof) of the principal amount of Securities of such series of a denomination larger than the minimum authorized denomination for Securities of that series; provided, however, that no such partial redemption shall reduce the portion of the principal amount of a Security not redeemed to less than the minimum authorized denomination for Securities of such series.”

ARTICLE VI

PAYMENT

Section 6.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Section 1001 of the Base Indenture shall be amended by adding the following at the end of such Section:

“Alternatively, at the request of the registered Holder, the Company will pay the principal of (and premium, if any, on) and interest, if any, on the Notes by wire transfer of immediately available funds to an account at a bank in New York City, on the date when such amount is due and payable. To request payment by wire transfer, the registered Holder must give the Paying Agent appropriate transfer instructions at least 15 Business Days before the requested payment is due. In the case of any interest payment due on an Interest Payment Date, the instructions must be given by the person who is the registered Holder on the relevant Regular Record Date. Any wire instructions, once properly given, will remain in effect unless and until new instructions are given in accordance with this Section.”

ARTICLE VII

MEETINGS OF HOLDERS OF SECURITIES

Section 7.01. Except as may be provided in a Future Supplemental Indenture, for the benefit of the Holders of the Notes but no other series of Securities under the Indenture, whether now or hereafter issued and Outstanding, Section 1505 of the Base Indenture shall be amended by replacing clause (c) thereof with the following:

“(c) At any meeting of Holders, each Holder of a Security of such series or proxy shall be entitled to one vote for each $25.00 principal amount of the Outstanding Securities of such series held or represented by such Holder; provided, however, that no vote shall be cast or counted at any meeting in respect of any Security challenged as not Outstanding and ruled by the chairman of the meeting to be not Outstanding. The chairman of the meeting shall have no right to vote, except as a Holder of a Security of such series or proxy.”

ARTICLE VIII

MISCELLANEOUS

Section 8.01. This Second Supplemental Indenture and the Notes shall be governed by and construed in accordance with the law of the State of New York, without regard to principles of conflicts of laws. This Second Supplemental Indenture is subject to the provisions of the Trust Indenture Act that are required to be part of the Indenture and shall, to the extent applicable, be governed by such provisions.

Section 8.02. In case any provision in this Second Supplemental Indenture or in the Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

Section 8.03. This Second Supplemental Indenture may be executed in counterparts, each of which will be an original, but such counterparts will together constitute but one and the same Second Supplemental Indenture. The exchange of copies of this Second Supplemental Indenture and of signature pages by facsimile, .pdf transmission, email or other electronic means shall constitute effective execution and delivery of this Second Supplemental Indenture for all purposes. Signatures of the parties hereto transmitted by facsimile, .pdf transmission, email or other electronic means shall be deemed to be their original signatures for all purposes.

Section 8.04. The Base Indenture, as supplemented and amended by this Second Supplemental Indenture, is in all respects ratified and confirmed, and the Base Indenture and this Second Supplemental Indenture shall be read, taken and construed as one and the same instrument with respect to the Notes. All provisions included in this Second Supplemental Indenture supersede any conflicting provisions included in the Base Indenture with respect to the Notes, unless not permitted by law. The Trustee accepts the trusts created by the Base Indenture, as supplemented by this Second Supplemental Indenture, and agrees to perform the same upon the terms and conditions of the Base Indenture, as supplemented by this Second Supplemental Indenture.

Section 8.05. The provisions of this Second Supplemental Indenture shall become effective as of the date hereof.

Section 8.06. Notwithstanding anything else to the contrary herein, the terms and provisions of this Second Supplemental Indenture shall apply only to the Notes and shall not apply to any other series of Securities under the Indenture and this Second Supplemental Indenture shall not and does not otherwise affect, modify, alter, supplement

IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental Indenture to be duly executed as of the day and year first above written.

NEW MOUNTAIN FINANCE CORPORATION


By:	/s/ Shiraz Y. Kajee
	Name:	Shiraz Y. Kajee
	Title:	Chief Financial Officer and Treasurer


U.S. BANK NATIONAL ASSOCIATION, as Trustee


By:	/s/ Karen R. Beard
	Name:	Karen R. Beard
	Title:	Vice President

[Signature page to Second Supplemental Indenture]

Exhibit A — Form of Global Note

This Security is a Global Security within the meaning of the Indenture hereinafter referred to and is registered in the name of The Depository Trust Company or a nominee thereof. This Security may not be exchanged in whole or in part for a Security registered, and no transfer of this Security in whole or in part may be registered, in the name of any Person other than The Depository Trust Company or a nominee thereof, except in the limited circumstances described in the Indenture.

Unless this certificate is presented by an authorized representative of The Depository Trust Company to the issuer or its agent for registration of transfer, exchange or payment and such certificate issued in exchange for this certificate is registered in the name of Cede & Co., or such other name as requested by an authorized representative of The Depository Trust Company, any transfer, pledge or other use hereof for value or otherwise by or to any person is wrongful, as the registered owner hereof, Cede & Co., has an interest herein.

New Mountain Finance Corporation

No.		$
		CUSIP No. 647551 209
		ISIN No. US6475512090

5.75% Notes due 2023

New Mountain Finance Corporation, a corporation duly organized and existing under the laws of Delaware (herein called the “Company,” which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to Cede & Co., or registered assigns, the principal sum of (U.S. ) on October 1, 2023, and to pay interest thereon from September 25, 2018, or from the most recent Interest Payment Date to which interest has been paid or duly provided for, quarterly on January 1, April 1, July 1 and October 1, commencing January 1, 2019, at the rate of 5.75% per annum, until the principal hereof is paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security is registered at the close of business on the Regular Record Date for such interest, which shall be December 15, March 15, June 15 or September 15 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture. This Security may be issued as part of a series.

Payment of the principal of (and premium, if any, on) and any such interest on this Security will be made at the office of the Trustee located at 111 Fillmore Avenue, St. Paul, MN 55107, Attention: NEW MOUNTAIN FINANCE CORPORATION (5.75% Notes Due 2023) or at such other address as designated by the Trustee, in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts; provided, however, that at the option of the Company payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register; provided, further, however, that, at the request of the registered Holder, the Company will pay the principal of (and premium, if any, on) and interest, if any, on the Securities by wire transfer of immediately available funds to an account at a bank in New York City, on the date when such amount is due and payable and as further set forth in Section 1001 of the Indenture; provided, further, however, that so long as this Security is registered to Cede & Co., such payment will be made by wire transfer in accordance with the procedures established by The Depository Trust Company and the Trustee.

IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed.

Dated:

			NEW MOUNTAIN FINANCE CORPORATION

			By:
			Name:
			Title:

Attest:

By:
Name:
Title:

This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture.

Dated:

	U.S. BANK NATIONAL ASSOCIATION, as Trustee

	By:
		Authorized Signatory

New Mountain Finance Corporation

5.75% Notes due 2023

This Security is one of a duly authorized issue of Senior Securities of the Company (herein called the “Securities”), issued and to be issued in one or more series under an Indenture, dated as of August 20, 2018 (herein called the “Base Indenture”, which term shall have the meaning assigned to it in such instrument), between the Company and U.S. Bank National Association, as Trustee (herein called the “Trustee”, which term includes any successor trustee under the Base Indenture), and reference is hereby made to the Base Indenture for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee, and the Holders of the Securities and of the terms upon which the Securities are, and are to be, authenticated and delivered, as amended and supplemented by the Second Supplemental Indenture relating to the Securities, dated as of September 25, 2018, by and between the Company and the Trustee (herein called the “Second Supplemental Indenture”; the Second Supplemental Indenture, together with the Base Indenture, collectively are herein called the “Indenture”). In the event of any conflict between the Base Indenture and the Second Supplemental Indenture, the Second Supplemental Indenture shall govern and control.

This Security is one of the series designated on the face hereof, which series is initially limited in aggregate principal amount to $ (or up to $ in aggregate principal amount if the underwriters’ overallotment option to purchase additional Securities is exercised in full). Under a Board Resolution, Officers’ Certificate pursuant to Board Resolutions or an indenture supplement, the Company may from time to time, without the consent of the Holders of Securities, issue additional Securities of this series (in any such case “Additional Securities”) having the same ranking and the same interest rate, maturity and other terms as the Securities; provided that, if such Additional Securities are not fungible with the Securities (or any other tranche of Additional Securities for U.S. federal income tax purposes, then such Additional Securities will have a different CUSIP numbers from the Securities (and any such other tranche of Additional Securities). Any Additional Securities and the existing Securities will constitute a single series under the Indenture and all references to the relevant Securities herein shall include the Additional Securities unless the context otherwise requires. The aggregate amount of outstanding Securities represented hereby may from time to time be reduced or increased, as appropriate, to reflect exchanges and redemptions.

The Securities of this series are subject to redemption in whole or in part at any time or from time to time, at the option of the Company, on or after October 1, 2020, at a Redemption Price per Security equal to 100% of the outstanding principal amount thereof plus accrued and unpaid interest payments otherwise payable for the then-current quarterly interest period accrued to, but excluding, the Redemption Date.

Notice of redemption shall be given in writing and mailed, first-class postage prepaid or by overnight courier guaranteeing next-day delivery, to each Holder of the Securities to be redeemed, not less than thirty (30) nor more than sixty (60) days prior to the Redemption Date, at the Holder’s address appearing in the Security Register. All notices of redemption shall contain the information set forth in Section 1104 of the Base Indenture.

Any exercise of the Company’s option to redeem the Securities will be done in compliance with the Indenture and the Investment Company Act, to the extent applicable.

If the Company elects to redeem only a portion of the Securities, the Trustee or, with respect to global Securities, the Depositary will determine the method for selecting the particular Securities to be redeemed, in accordance with Section 1.01 of the Second Supplemental Indenture, Section 1103 of the Base Indenture and the Investment Company Act, to the extent applicable. In the event of redemption of this Security in part only, a new Security or Securities of this series and of like tenor for the unredeemed portion hereof will be issued in the name of the Holder hereof upon the cancellation hereof.

Unless the Company defaults in payment of the Redemption Price, on and after the Redemption Date, interest will cease to accrue on the Securities called for redemption.

Holders of Securities do not have the option to have the Securities repaid prior to October 1, 2023.

The Indenture contains provisions for defeasance at any time of the entire indebtedness of this Security or certain restrictive covenants and Events of Default with respect to this Security, in each case upon compliance with certain conditions set forth in the Indenture.

If an Event of Default (other than an Event of Default referred to in clause (5) or (6) of Section 501 of the Base Indenture) with respect to Securities of this series shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture. If an Event of Default referred to in clause (5) or (6) of Section 501 of the Base Indenture with respect to the Company has occurred, the entire principal amount of all of the Securities shall automatically become due and immediately payable.

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Securities of each series to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of not less than a majority in principal amount of the Securities at the time Outstanding of each series to be affected. The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Securities of each series at the time Outstanding, on behalf of the Holders of all Securities of such series, to waive compliance by the Company with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security.

As provided in and subject to the provisions of the Indenture, the Holder of this Security shall not have the right to institute any proceeding with respect to the Indenture or for the appointment of a receiver or trustee or for any other remedy thereunder, unless such Holder shall have previously given the Trustee written notice of a continuing Event of Default with respect to the Securities of this series, the Holders of not less than 25% in principal amount of the Securities of this series at the time Outstanding shall have made written request to the Trustee to institute proceedings in respect of such Event of Default as Trustee and offered the Trustee indemnity, security or both reasonably satisfactory to the Trustee against the costs, expenses and liabilities to be incurred in compliance with such request, and the Trustee shall not have received from the Holders of a majority in principal amount of Securities of this series at the time Outstanding a direction inconsistent with such request, and shall have failed to institute any such proceeding, for sixty (60) days after receipt of such notice, request and offer of indemnity and/or security. The foregoing shall not apply to any suit instituted by the Holder of this Security for the enforcement of any payment of principal hereof or any premium or interest hereon on or after the respective due dates expressed herein.

No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of and any premium and interest on this Security at the times, place and rate, and in the coin or currency, herein prescribed.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Security is registrable in the Security Register, upon surrender of this Security for registration of transfer at the office or agency of the Company in any place where the principal of and any premium and interest on this Security are payable, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the Security Registrar duly executed by, the Holder hereof or his attorney duly authorized in writing, and thereupon one

or more new Securities of this series and of like tenor, of authorized denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees.

The Securities of this series are issuable only in registered form without coupons in denominations of $25.00 and any integral multiples of $25.00 in excess thereof. As provided in the Indenture and subject to certain limitations therein set forth, Securities of this series are exchangeable for a like aggregate principal amount of Securities of this series and of like tenor of a different authorized denomination, as requested by the Holder surrendering the same.

No service charge shall be made for any such registration of transfer or exchange, but the Company, the Trustee, or the Security Registrar may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

Prior to due presentment of this Security for registration of transfer, the Company, the Trustee, or the Security Registrar and any agent of the Company, the Trustee, or the Security Registrar shall treat the Person in whose name this Security is registered as the owner hereof for all purposes, whether or not this Security be overdue, and none of the Company, the Trustee, the Security Registrar, or any agent thereof shall be affected by notice to the contrary.

All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

To the extent any provision of this Security conflicts with the express provisions of the Indenture, the provisions of the Indenture shall govern and be controlling.

The Indenture and this Security shall be governed by and construed in accordance with the laws of the State of New York, without regard to principles of conflicts of laws.