    <SEC-DOCUMENT>0001104659-21-122025-index.html : 20211001
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    <ACCEPTANCE-DATETIME>20211001164135
    ACCESSION NUMBER:		0001104659-21-122025
    CONFORMED SUBMISSION TYPE:	S-4
    PUBLIC DOCUMENT COUNT:		19
    FILED AS OF DATE:		20211001
    DATE AS OF CHANGE:		20211001

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			OLD SECOND BANCORP INC
    		CENTRAL INDEX KEY:			0000357173
    		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
    		IRS NUMBER:				363143493
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		S-4
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-259964
    		FILM NUMBER:		211299461

    	BUSINESS ADDRESS:
    		STREET 1:		37 S RIVER ST
    		CITY:			AURORA
    		STATE:			IL
    		ZIP:			60507
    		BUSINESS PHONE:		6308920202

    	MAIL ADDRESS:
    		STREET 1:		37 SOUTH RIVER STREET
    		CITY:			AURORA
    		STATE:			IL
    		ZIP:			60507
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>S-4
    <SEQUENCE>1
    <FILENAME>tm2125387-1_s4.htm
    <DESCRIPTION>S-4
    <TEXT>
    Document 1 - file: tm2125387-1_s4.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-5.1
    <SEQUENCE>2
    <FILENAME>tm2125387d2_ex5-1.htm
    <DESCRIPTION>EXHIBIT 5.1
    <TEXT>
    Document 2 - file: tm2125387d2_ex5-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.1
    <SEQUENCE>3
    <FILENAME>tm2125387d2_ex23-1.htm
    <DESCRIPTION>EXHIBIT 23.1
    <TEXT>
    Document 3 - file: tm2125387d2_ex23-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.2
    <SEQUENCE>4
    <FILENAME>tm2125387d2_ex23-2.htm
    <DESCRIPTION>EXHIBIT 23.2
    <TEXT>
    Document 4 - file: tm2125387d2_ex23-2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>5
    <FILENAME>tm2125387d2_ex99-1.htm
    <DESCRIPTION>EXHIBIT 99.1
    <TEXT>
    Document 5 - file: tm2125387d2_ex99-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.2
    <SEQUENCE>6
    <FILENAME>tm2125387d2_ex99-2.htm
    <DESCRIPTION>EXHIBIT 99.2
    <TEXT>
    Document 6 - file: tm2125387d2_ex99-2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.3
    <SEQUENCE>7
    <FILENAME>tm2125387d2_ex99-3.htm
    <DESCRIPTION>EXHIBIT 99.3
    <TEXT>
    Document 7 - file: tm2125387d2_ex99-3.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.4
    <SEQUENCE>8
    <FILENAME>tm2125387d2_ex99-4.htm
    <DESCRIPTION>EXHIBIT 99.4
    <TEXT>
    Document 8 - file: tm2125387d2_ex99-4.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.5
    <SEQUENCE>9
    <FILENAME>tm2125387d2_ex99-5.htm
    <DESCRIPTION>EXHIBIT 99.5
    <TEXT>
    Document 9 - file: tm2125387d2_ex99-5.htm

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    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>image_001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: image_001.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>image_002.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: image_002.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>lg_citinoregister-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: lg_citinoregister-4c.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>lg_crowe-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: lg_crowe-4c.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>lg_crowellpindepen-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: lg_crowellpindepen-4c.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>lg_kbfstifel-4clr.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: lg_kbfstifel-4clr.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>lg_oldsecond-4clr.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: lg_oldsecond-4clr.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>lg_westsuburban-pn.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 17 - file: lg_westsuburban-pn.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>sg_crowellpnew3-bw.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: sg_crowellpnew3-bw.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>sg_keefebruwood-bw.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: sg_keefebruwood-bw.jpg

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