#1 Of this total, 211 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 12-31-23.

#2 Of this total, 22 shares were allocated during the fourth quarter pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 12-31-23.

#1 Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 77,088 restricted stock units on the date of the grant, 38,544 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 38,544 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 Of this total are 101,316 shares of Performance Based Restricted Stock Units and 80,840 shares of Restricted Stock Units.

#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 reporting period. At the time of grant, the reporting person reported an acquisition of 20,476 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 teh performance period.

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

#3 Included in this total are 267,543 shares held with a broker; 21,716 shares held outright solely by the reporting person and 148 shares held jointly with the spouse.

#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 reporting period. At the time of grant, the reporting person reported an acquisition of 20,476 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 teh performance period.

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

#3 Included in this total are 267,543 shares held with a broker; 21,716 shares held outright solely by the reporting person and 148 shares held jointly with the spouse.