Form 4 for OSBC OLD SECOND BANCORP INC

Accepted 2026-03-04 00:00:00 ET · period of report 2026-03-02 · accession 0001673321-26-000006 · 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
	2026-03-04	2026-03-02	OSBC	Pilmer Donald	EVP	F - Tax	$19.91	-2,720	73.1K	-4%	-$54.2K
	2026-03-04	2026-03-02	OSBC	Pilmer Donald	EVP	A - Grant	$0.00	+9,201	66.6K	+16%	$0

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	F	D	2,720	$19.91	73,054	D	—	—	(F2) Represents shares withheld by the issuer to satisfy applicable tax withholding obligations in connection with the vesting of 9,201 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 9,919 shares in the reporting person's name outright and 63,135 shares held in the reporting person's name in a brokerage account.
2	Common	Old Second Bancorp, Inc. Common Stock	2026-03-02	A	A	9,201	$0.00	66,573	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 5,256 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 3,945 shares.