X0407 4 2023-06-30 0000357173 OLD SECOND BANCORP INC OSBC 0001673321 Pilmer Donald 37 S. RIVER ST. AURORA IL 60506 false true false false EVP 0 Old Second Bancorp, Inc. Common Stock 2023-06-30 5 A 0 17 0 A 3874 I By 401-K Plan Old Second Bancorp, Inc. Common Stock 176 I By Profit Sharing Plan Old Second Bancorp, Inc. Common Stock 1450 I Spouse's IRA Old Second Bancorp, Inc. Common Stock 50976 D Restricted Stock Units 28880 D Of this total, 17 shares were allocated during the second quarter pursuant to the Old Second Bancorp, Inc. Employee Salary Savings Plan. Information herein was provided by the Plan Trustee as of 6-30-23. These shares are held in spouse's IRA for which Mr. Pilmer is listed as a beneficiary. These shares are held in Mr. Pilmer's name with a broker. Of this total, 23,624 shares are Restricted Stock Units and 5,256 shares are Performance-based Restricted Stock Units. /s/ Shirley Cantrell, Attorney-in-Fact 2023-06-30