Stock award and tax withholding for Old Second Bancorp (OSBC) vice chair

Rhea-AI Filing Summary

Old Second Bancorp vice chairman Gary S. Collins reported equity compensation activity in company stock. On March 2, 2026, he acquired 14,432 shares of Old Second Bancorp, Inc. common stock at $0.00 per share as a grant tied to the vesting of performance-based restricted stock units under the company’s 2019 Equity Incentive Plan. A footnote explains that earlier he had reported 8,246 units based on target performance and that actual performance above target led to an additional 6,186 shares being delivered. The company withheld 4,228 shares at $19.91 per share to cover tax obligations related to this vesting, with the remaining shares added to his common stock holdings. After these updates, he holds 46,624 shares of common stock directly, 78,256.085 shares indirectly through IRAs, 6,805 shares indirectly via a 401(k), and 37,312 restricted stock units directly.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

COLLINS GARY S

(Last) (First) (Middle)

37 S. RIVER ST.

(Street)

AURORA IL 60302

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
OLD SECOND BANCORP INC [ OSBC ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	VICE CHAIRMAN

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Old Second Bancorp, Inc. Common Stock	03/02/2026		A		14,432(1)	A	$0	5,462	D
Old Second Bancorp, Inc. Common Stock	03/02/2026		F		4,228(2)	D	$19.91	15,666	D
Old Second Bancorp, Inc. Common Stock								46,624(3)	D
Old Second Bancorp, Inc. Common Stock								78,256.085(4)	I	IRA
Old Second Bancorp, Inc. Common Stock								6,805	I	By 401-K
Restricted Stock Units								37,312	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 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 8,246 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 6,186 shares.

2. Represents shares withheld by the issuer to satisfy applicable tax withholding obligations in connection with the vesting of 14,432 previously reported performance-based restricted stock units, the remaining shares of which were issued and added to the reporting person's common stock holdings.

3. Included in this total are 41,762 shares of restricted stock units and 69,236.306 shares in Mr. Collins name in a broker account.

4. Included in this total are 41,000 shares in a ROTH IRA and 37,256.085 in a traditional IRA.

	/s/ Shirley Cantrell, Attorney-in-Fact	03/04/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What did OSBC vice chairman Gary S. Collins report in this Form 4 filing?

Gary S. Collins reported a stock award and related tax withholding. He received 14,432 Old Second Bancorp shares from vesting performance-based restricted stock units and had 4,228 shares withheld to cover taxes at $19.91 per share.

How many Old Second Bancorp (OSBC) shares did Gary S. Collins acquire?

He acquired 14,432 shares of Old Second Bancorp, Inc. common stock at $0.00 per share. These came from vesting performance-based restricted stock units granted under the 2019 Equity Incentive Plan after performance goals were achieved.

Why were 4,228 OSBC shares withheld from Gary S. Collins?

4,228 shares were withheld to satisfy tax obligations arising from the vesting of 14,432 performance-based restricted stock units. The issuer retained these shares at $19.91 per share, while the remaining shares were issued to Collins’ common stock holdings.

What performance detail is disclosed about Gary S. Collins’ restricted stock units at OSBC?

The filing states that 8,246 units were initially reported based on target performance. Actual performance exceeded target, resulting in an additional 6,186 shares being delivered when the performance-based restricted stock units vested under the 2019 Equity Incentive Plan.

What are Gary S. Collins’ total direct OSBC share and RSU holdings after these transactions?

After these transactions, Collins directly holds 46,624 shares of Old Second Bancorp common stock and 37,312 restricted stock units. These figures reflect the new shares issued from vesting after tax withholdings were satisfied with 4,228 shares.

What indirect Old Second Bancorp (OSBC) holdings does Gary S. Collins report?

Collins reports 78,256.085 Old Second Bancorp shares indirect through IRAs and 6,805 shares indirect via a 401(k) plan. The filing notes these as separate from his direct common stock and restricted stock unit holdings at the company.