<SEC-DOCUMENT>0001127602-21-023282.txt : 20210806
<SEC-HEADER>0001127602-21-023282.hdr.sgml : 20210806
<ACCEPTANCE-DATETIME>20210806163707
ACCESSION NUMBER:		0001127602-21-023282
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210805
FILED AS OF DATE:		20210806
DATE AS OF CHANGE:		20210806

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DONNELLY MICHAEL J
		CENTRAL INDEX KEY:			0001157903

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12508
		FILM NUMBER:		211153432

	MAIL ADDRESS:	
		STREET 1:		C/O S&T BANK ACCOUNTING DEPT
		STREET 2:		P O BOX 190
		CITY:			INDIANA
		STATE:			PA
		ZIP:			15701

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			S&T BANCORP INC
		CENTRAL INDEX KEY:			0000719220
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				251434426
		STATE OF INCORPORATION:			PA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		800 PHILADELPHIA STREET
		STREET 2:		PO BOX 190
		CITY:			INDIANA
		STATE:			PA
		ZIP:			15701
		BUSINESS PHONE:		724-427-2347

	MAIL ADDRESS:	
		STREET 1:		800 PHILADELPHIA STREET
		STREET 2:		PO BOX 190
		CITY:			INDIANA
		STATE:			PA
		ZIP:			15701
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>form4a.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2021-08-05</periodOfReport>

    <dateOfOriginalSubmission>2021-08-06</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000719220</issuerCik>
        <issuerName>S&amp;T BANCORP INC</issuerName>
        <issuerTradingSymbol>STBA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001157903</rptOwnerCik>
            <rptOwnerName>DONNELLY MICHAEL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>800 PHILADELPHIA STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>INDIANA</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>15701</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1465</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>29.34</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16774</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17564</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Indiana Printing &amp; Publishing Company</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The Registrant granted the annual Director Award effective on the date that the Form S-8 Registration Statement for the S&amp;T Bancorp, Inc. 2021 Incentive Stock Plan was filed with the Securities Exchange Commission and under the terms of the Restricted Stock Award Agreement between the Company and the Director. The vesting date of the award is May 16, 2022.</footnote>
        <footnote id="F2">Price of $29.24 on original Form 4 dated August 6, 2021 was incorrect.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Timothy P. McKee POA for Michael Donnelly</signatureName>
        <signatureDate>2021-08-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
