    <SEC-DOCUMENT>0001104659-25-037832-index.html : 20250423
    <SEC-HEADER>0001104659-25-037832.hdr.sgml : 20250423
    <ACCEPTANCE-DATETIME>20250423113337
    ACCESSION NUMBER:		0001104659-25-037832
    CONFORMED SUBMISSION TYPE:	S-4
    PUBLIC DOCUMENT COUNT:		14
    FILED AS OF DATE:		20250423
    DATE AS OF CHANGE:		20250423

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			OLD SECOND BANCORP INC
    		CENTRAL INDEX KEY:			0000357173
    		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
    		ORGANIZATION NAME:           	02 Finance
    		EIN:				363143493
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		S-4
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-286687
    		FILM NUMBER:		25859842

    	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>tm2511100-1_s4.htm
    <DESCRIPTION>S-4
    <TEXT>
    Document 1 - file: tm2511100-1_s4.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-5.1
    <SEQUENCE>2
    <FILENAME>tm2511100d2_ex5-1.htm
    <DESCRIPTION>EXHIBIT 5.1
    <TEXT>
    Document 2 - file: tm2511100d2_ex5-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.1
    <SEQUENCE>3
    <FILENAME>tm2511100d2_ex23-1.htm
    <DESCRIPTION>EXHIBIT 23.1
    <TEXT>
    Document 3 - file: tm2511100d2_ex23-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.2
    <SEQUENCE>4
    <FILENAME>tm2511100d2_ex23-2.htm
    <DESCRIPTION>EXHIBIT 23.2
    <TEXT>
    Document 4 - file: tm2511100d2_ex23-2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>5
    <FILENAME>tm2511100d2_ex99-1.htm
    <DESCRIPTION>EXHIBIT 99.1
    <TEXT>
    Document 5 - file: tm2511100d2_ex99-1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.2
    <SEQUENCE>6
    <FILENAME>tm2511100d2_ex99-2.htm
    <DESCRIPTION>EXHIBIT 99.2
    <TEXT>
    Document 6 - file: tm2511100d2_ex99-2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-FILING FEES
    <SEQUENCE>7
    <FILENAME>tm2511100d2_ex-filingfees.htm
    <DESCRIPTION>EX-FILING FEES
    <TEXT>
    Document 7 - file: tm2511100d2_ex-filingfees.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>lg_bancorpfinancial-4clr.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: lg_bancorpfinancial-4clr.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>lg_kbw-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: lg_kbw-4c.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>lg_oldsecondbancorp-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: lg_oldsecondbancorp-4c.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>lg_rsm-4c.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: lg_rsm-4c.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>tm2511100d2_ex5-1mg001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: tm2511100d2_ex5-1mg001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>tm2511100d2_ex99-1img01.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: tm2511100d2_ex99-1img01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>tm2511100d2_ex99-1img02.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: tm2511100d2_ex99-1img02.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>