<SEC-DOCUMENT>0001127602-21-018109.txt : 20210526
<SEC-HEADER>0001127602-21-018109.hdr.sgml : 20210526
<ACCEPTANCE-DATETIME>20210526212940
ACCESSION NUMBER:		0001127602-21-018109
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210525
FILED AS OF DATE:		20210526
DATE AS OF CHANGE:		20210526

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KABAT KEVIN T
		CENTRAL INDEX KEY:			0001024525
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16189
		FILM NUMBER:		21968271

	MAIL ADDRESS:	
		STREET 1:		UNUM GROUP
		STREET 2:		1 FOUNTAIN SQUARE
		CITY:			CHATTANOOGA
		STATE:			TN
		ZIP:			37402

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NISOURCE INC.
		CENTRAL INDEX KEY:			0001111711
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC & OTHER SERVICES COMBINED [4931]
		IRS NUMBER:				352108964
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		801 EAST 86TH AVE
		CITY:			MERRILLVILLE
		STATE:			IN
		ZIP:			46410-6272
		BUSINESS PHONE:		2196475200

	MAIL ADDRESS:	
		STREET 1:		801 EAST 86TH AVE
		CITY:			MERRILLVILLE
		STATE:			IN
		ZIP:			46410-6272

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NISOURCE INC/DE
		DATE OF NAME CHANGE:	20001103

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NEW NISOURCE INC
		DATE OF NAME CHANGE:	20000412
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-05-25</periodOfReport>

    <issuer>
        <issuerCik>0001111711</issuerCik>
        <issuerName>NISOURCE INC.</issuerName>
        <issuerTradingSymbol>NI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001024525</rptOwnerCik>
            <rptOwnerName>KABAT KEVIN T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>NISOURCE INC.</rptOwnerStreet1>
            <rptOwnerStreet2>801 E. 86TH AVENUE</rptOwnerStreet2>
            <rptOwnerCity>MERRILLVILLE</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46410</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-05-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5922</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.33</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>39862.763</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents an award of restricted stock units (&quot;RSU&quot;) granted as part of the non-employee director's annual compensation and which vests in full on the last day of the director's annual term for which the RSUs are awarded, subject to certain acceleration conditions. RSUs represent a contingent right to receive one share of the Company's common stock upon vesting pursuant to the Company's 2020 Omnibus Plan.</footnote>
        <footnote id="F2">This amount includes 265.275 RSUs received pursuant to the dividend equivalent provisions of the RSU awards and which are subject to the same vesting conditions as the underlying RSUs.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Anne-Marie D'Angelo, Attorney-in-Fact</signatureName>
        <signatureDate>2021-05-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
