Darin Patrick Campbell - 17 Feb 2026 Form 4 Insider Report for OLD SECOND BANCORP INC (OSBC)

Role: President, Powersports Lending, Director
Signature: /s/ Shirley Cantrell, Attorney-in-Fact
Issuer symbol: OSBC
Transactions as of: 17 Feb 2026
Net transactions value: $0
Form type: 4
Filing time: 24 Feb 2026, 18:44:39 UTC
Previous filing: 18 Feb 2026
Next filing: 19 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Campbell Darin Patrick	President, Powersports Lending, Director	37 S. RIVER ST., AURORA	/s/ Shirley Cantrell, Attorney-in-Fact	24 Feb 2026	0002074132

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	OSBC	Restricted Stock	Award	$0	+10,562		$0.000000	10,562	17 Feb 2026	Direct	F1
holding	OSBC	Old Second Bancorp, Inc. Common Stock						274,589	17 Feb 2026	Direct

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 10,562 restricted stock units on the date of the grant, 5,281 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 5,281 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.

Content

Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 10,562 restricted stock units on the date of the grant, 5,281 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 5,281 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.