Form 4 for OSBC OLD SECOND BANCORP INC

Accepted 2026-03-04 00:00:00 ET · period of report 2026-03-02 · accession 0001840027-26-000008 · 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
	2026-03-04	2026-03-02	OSBC	Gartelmann Richard A JR	EVP	A - Grant	$0.00	+4,523	26.6K	+21%	$0
	2026-03-04	2026-03-02	OSBC	Gartelmann Richard A JR	EVP	F - Tax	$19.91	-1,537	29.6K	-5%	-$30.6K

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	Old Second Bancorp, Inc. Common Stock	2026-03-02	A	A	4,523	$0.00	26,565	D	—	—	(F1) 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. The reporting person reported an acquisition of 2,585 on Form 4 filed February 21, 2023, 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 which resulted in an additional grant of 1,938 shares.
2	Common	Old Second Bancorp, Inc. Common Stock	2026-03-02	F	D	1,537	$19.91	29,551	D	—	—	(F2) Represents shares withheld by the issuer to satisfy applicable tax withholding obligations in connection with the vesting of 4,523 previously reported performance-based restricted stock units, the remaining shares of which were issued and added to the reporting person's common stock holdings. (F3) Included in this total are 4,677 shares held outright in the reporting person's name and 24,874 shares held with a brokerage firm.