<SEC-DOCUMENT>0001515170-21-000002.txt : 20210823
<SEC-HEADER>0001515170-21-000002.hdr.sgml : 20210823
<ACCEPTANCE-DATETIME>20210823161035
ACCESSION NUMBER:		0001515170-21-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210820
FILED AS OF DATE:		20210823
DATE AS OF CHANGE:		20210823

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Weinstein Adam
		CENTRAL INDEX KEY:			0001515170

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	814-00832
		FILM NUMBER:		211196967

	MAIL ADDRESS:	
		STREET 1:		C/O NEW MOUNTAIN FINANCE CORPORATION
		STREET 2:		787 7TH AVENUE, 48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			New Mountain Finance Corp
		CENTRAL INDEX KEY:			0001496099
		IRS NUMBER:				272978010
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1633 BROADWAY
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019
		BUSINESS PHONE:		2127300200

	MAIL ADDRESS:	
		STREET 1:		1633 BROADWAY
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	New Mountain Guardian Corp
		DATE OF NAME CHANGE:	20100706
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_162974940934586.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001496099</issuerCik>
        <issuerName>New Mountain Finance Corp</issuerName>
        <issuerTradingSymbol>NMFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001515170</rptOwnerCik>
            <rptOwnerName>Weinstein Adam</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW MOUNTAIN CAPITAL, L.L.C.</rptOwnerStreet1>
            <rptOwnerStreet2>1633 BROADWAY, 48TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, CAO and Director</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15080</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.077</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>302851.25</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported is the average weighted price. The shares were purchased in multiple transactions. The reporting person undertakes to provide to the SEC, the issuer and any security holder, upon request, full information regarding the number of shares and the prices at which the shares were purchased</footnote>
        <footnote id="F2">Includes shares acquired under the New Mountain Finance Corporation dividend reinvestment plan since the filing of Mr. Weinstein's previous beneficial ownership report on Form 4 on September 4, 2020.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Adam Weinstein</signatureName>
        <signatureDate>2021-08-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
