<SEC-DOCUMENT>0001104659-20-076465.txt : 20200624
<SEC-HEADER>0001104659-20-076465.hdr.sgml : 20200624
<ACCEPTANCE-DATETIME>20200624164947
ACCESSION NUMBER:		0001104659-20-076465
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200623
FILED AS OF DATE:		20200624
DATE AS OF CHANGE:		20200624

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Herman Philip Karl
		CENTRAL INDEX KEY:			0001799303

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38650
		FILM NUMBER:		20986146

	MAIL ADDRESS:	
		STREET 1:		C/O Y-MABS THERAPEUTICS, INC.
		STREET 2:		230 PARK AVENUE, SUITE 3350
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10169

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Y-mAbs Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001722964
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				474619612
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		750 THIRD AVENUE
		STREET 2:		9TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
		BUSINESS PHONE:		212-847-9841

	MAIL ADDRESS:	
		STREET 1:		750 THIRD AVENUE
		STREET 2:		9TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-06-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001722964</issuerCik>
        <issuerName>Y-mAbs Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>YMAB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001799303</rptOwnerCik>
            <rptOwnerName>Herman Philip Karl</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O Y-MABS THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>230 PARK AVENUE SUITE 3350</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10169</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP &amp; CCO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>48.67</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-06-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2030-06-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Stock options granted to the Reporting Person pursuant to the 2018 Equity Incentive Plan of Y-mAbs Therapeutics, Inc.</footnote>
        <footnote id="F2">The stock option shall vest and become exercisable as to 25% of the shares subject to the option on June 23, 2021, and thereafter vests and become exercisable as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Philip Karl Herman</signatureName>
        <signatureDate>2020-06-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>