#1 Of this total, 234 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, 129 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 Shares delivered to the reporting person pursuant to vesting of performance-based restricted stock units granted under the Old Second Bancorp, Inc. 2019 Equity Incentive Plan, as Amended and Restated and vested upon achievement of performance goals for the applicable performance period. At the time of grant, the reporting person reported an acquisition of 10,616 of these shares, which represented the number of shares that would be delivered if target performance was achieved during the performance period. Actual performance exceeded the target performance for the performance period.

#2 Shares withheld for taxes upon settlement in shares of the performance-based restricted stock units previously granted to the reporting person.

#1 Shares delivered to the reporting person pursuant to vesting of performance-based restricted stock units granted under the Old Second Bancorp, Inc. 2019 Equity Incentive Plan, as Amended and Restated and vested upon achievement of performance goals for the applicable performance period. At the time of grant, the reporting person reported an acquisition of 10,616 of these shares, which represented the number of shares that would be delivered if target performance was achieved during the performance period. Actual performance exceeded the target performance for the performance period.

#2 Shares withheld for taxes upon settlement in shares of the performance-based restricted stock units previously granted to the reporting person.

#1 These shares were allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Salary and Savings Plan. Information herein was provided by the Plan Trustee as of 09-30-24.