#1 Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 7,150 restricted stock units on the date of the grant, 3,575 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 3,575 of which are performance-based restricted stock units that may vest and convert to shares within a range from 0% to 175% 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 in 3 to 5 business days from the date of vesting.

#2 Included in this total are 6,160 shares of Performance Based Restricted Stock Units and 10,223 shares of Restricted Stock Units.

#1 Of this total, 59 shares were allocated during the fourth quarter pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the plan Trustee as of 12-31-2023.

#1 Of this total, 271 shares were allocated during the first quarter of 2024, pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the plan Trustee as of 3-31-24.

#2 Of this total, 110 shares were allocated during the second quarter of 2024, pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the plan Trustee as of 6-30-24.

#1 Of this total, 271 shares were allocated during the first quarter of 2024, pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the plan Trustee as of 3-31-24.

#2 Of this total, 110 shares were allocated during the second quarter of 2024, pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the plan Trustee as of 6-30-24.