<SEC-DOCUMENT>0001127602-19-034186.txt : 20191203
<SEC-HEADER>0001127602-19-034186.hdr.sgml : 20191203
<ACCEPTANCE-DATETIME>20191203184958
ACCESSION NUMBER:		0001127602-19-034186
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20191201
FILED AS OF DATE:		20191203
DATE AS OF CHANGE:		20191203

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Barsz Peter Richard
		CENTRAL INDEX KEY:			0001732803

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12508
		FILM NUMBER:		191266884

	MAIL ADDRESS:	
		STREET 1:		1023 BENT ROAD
		CITY:			MEDIA
		STATE:			PA
		ZIP:			19063

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
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-12-01</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001732803</rptOwnerCik>
            <rptOwnerName>Barsz Peter Richard</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>2019-12-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3462</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>37.72</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3462</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-12-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>610</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>37.72</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4072</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Acquired pursuant to the Agreement and Plan of Merger (the &quot;Merger Agreement&quot;) by and between the Issuer and DNB Financial Corporation (&quot;DNB&quot;). Pursuant to the terms of the Merger Agreement, at the effective time of the Merger, each share of DNB common stock was converted into 1.22 shares of the Issuer's common stock.  Cash in lieu of fractional shares was paid at a rate of $38.09 per share.</footnote>
        <footnote id="F2">Restricted stock unit awarded by DNB vested in full, all restrictions thereon lapsed, at the effective time of the Merger.  Each such award was converted into the right to receive 1.22 shares of the Issuer's common stock as described in footnote 1.  S&amp;T had a market value of $37.72 per share on the effective time of the Merger.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Timothy P. McKee, POA for Peter R. Barsz</signatureName>
        <signatureDate>2019-12-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
