    <SEC-DOCUMENT>0000719220-20-000037-index.html : 20200518
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    <ACCEPTANCE-DATETIME>20200518093148
    ACCESSION NUMBER:		0000719220-20-000037
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		26
    CONFORMED PERIOD OF REPORT:	20200518
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20200518
    DATE AS OF CHANGE:		20200518

    FILER:

    	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

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-12508
    		FILM NUMBER:		20888248

    	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>8-K
    <SEQUENCE>1
    <FILENAME>form8k2020annualmeeting.htm
    <DESCRIPTION>8-K
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    Document 1 - file: form8k2020annualmeeting.htm

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    <FILENAME>stbaannualmeeting2020.htm
    <DESCRIPTION>EXHIBIT 99.1
    <TEXT>
    Document 2 - file: stbaannualmeeting2020.htm

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    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>3
    <FILENAME>stba-20200518.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 3 - file: stba-20200518.xsd

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    <DOCUMENT>
    <TYPE>EX-101.CAL
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    <FILENAME>stba-20200518_cal.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT
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    <FILENAME>stbaannualmeeting2020001.jpg
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    <TYPE>JSON
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    <SEQUENCE>23
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    <SEQUENCE>24
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    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>27
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