X0306 4/A 2023-02-21 2023-02-21 0000357173 OLD SECOND BANCORP INC OSBC 0001673321 Pilmer Donald 37 S. RIVER ST. AURORA IL 60506 false true false false EVP Restricted Stock Units 2023-02-21 4 A 0 10512 0 A 28880 D Old Second Bancorp, Inc. Common Stock 3846 I By 401-K Plan Old Second Bancorp, Inc. Common Stock 175 I By Profit Sharing Plan Old Second Bancorp, Inc. Common Stock 1450 I Spouse's IRA Old Second Bancorp, Inc. Common Stock 50956 D Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 10,512 restricted stock units on the date of grant, 5,256 of which are time-based restricted stock units that cliff vest on the third anniversary of the grant date, and 5,256 of which are performance-based restricted stock units that may vest and convert to shares within a range from 0% to 150% of the underlying performance-based restricted stock units originally awarded, depending on our compensation committee approved performance metrics. Vested shares, if any, will be delivered to the reporting person within 3 to 5 business days. These shares are held in spouse's IRA for which Mr. Pilmer is listed as a beneficiary. Included in this total are 44,923 shares held in a brokerage account and 6,033 shares held outright. /s/ Shirley Cantrell, Attorney-in-Fact 2023-03-03