#1 Of this total, 1 share was allocated during the first quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 3-31-24.

#2 Of this total, 1 share was allocated during the second quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 6-30-24.

#3 Of this total, 15 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.

#4 Of this total, 13 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, 1 share was allocated during the first quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 3-31-24.

#2 Of this total, 1 share was allocated during the second quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 6-30-24.

#3 Of this total, 15 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.

#4 Of this total, 13 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, 1 share was allocated during the first quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 3-31-24.

#2 Of this total, 1 share was allocated during the second quarter of 2024, pursuant to the Old Second Bancorp, Inc. Profit Sharing Plan and Trust. Information herein was provided by the plan Trustee as of 6-30-24.

#3 Of this total, 15 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.

#4 Of this total, 13 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 Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 16,064 restricted stock units on the date of the grant, 8,032 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 8,032 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, 13,288 shares are Performance Based Restricted Stock Units and 21,548 shares of Restricted Stock Units.