Form 4 for OSBC OLD SECOND BANCORP INC

Accepted 2026-02-24 00:00:00 ET · period of report 2026-02-17 · accession 0001840027-26-000006 · SEC index · Original document

Summary rows

Aggregated the way they appear in lists: one row per insider, transaction code and security table.

X	Filed	Traded	Ticker	Insider	Title	Type	Price	Qty	Owned	ΔOwn	Value
	2026-02-24	2026-02-17	OSBC	Gartelmann Richard A JR	EVP	A - Grant	$0.00	+5,912	26.5K	+29%	$0
	2026-02-24	2026-02-21	OSBC	Gartelmann Richard A JR	EVP	F - Tax	$20.57	-894	23.9K	-4%	-$18.4K

Purchase Sale Sale after option exercise All abbreviations

#	Table	Security	Date	Code	A/D	Shares	Price	Owned after	Own	Exercise / expiry	Underlying	Footnotes
1	Common	Restricted Stock Units	2026-02-17	A	A	5,912	$0.00	26,464	D	—	—	(F1) Each restricted stock unit represents a contingent right to receive one share of common stock. The reporting person was granted 5,912 restricted stock units on the date of the grant, 2,956 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 2,956 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	Common	Restricted Stock Units	2026-02-21	F	D	894	$20.57	23,879	D	—	—	(F2) Represents shares withheld by the issuer to satisfy applicable tax withholding obligations in connection with the vesting of 2,585 previously reported time-based restricted stock units, the remaining shares of which were issued and added to the reporting person's common stock holdings.