Old Second Bancorp (OSBC) director logs RSU grant and tax withholding

Rhea-AI Filing Summary

OLD SECOND BANCORP INC director Hugh H. McLean reported equity award activity involving restricted stock units and common stock. On February 17, 2026, he received a grant of 3,121 restricted stock units at $0.00 per unit under the company’s Long Term Incentive Plan, which carry a three-year cliff vesting schedule.

Upon vesting on the third anniversary of the prior grant, 3,077 shares of common stock were issued and added to his holdings, with a related tax-withholding disposition of 3,077 restricted stock units at $20.57 per share on February 21, 2026. Following these transactions, he directly held 10,595 restricted stock units and 157,274 shares of Old Second Bancorp, Inc. common stock.

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^*

MCLEAN HUGH H

(Last) (First) (Middle)

408 S. PROSPECT AVE

(Street)

ELMHURST IL 60126

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
02/17/2026

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
Restricted Stock Units	02/17/2026		A		3,121(1)	A	$0	13,672	D
Restricted Stock Units	02/21/2026		F		3,077(2)	D	$20.57	10,595	D
Old Second Bancorp, Inc. Common Stock								3,077(3)	D
Old Second Bancorp, Inc. Common Stock								157,274(4)	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. These represent restricted stock units granted pursuant to the Old Second Bancorp, Inc. Long Term Incentive Plan. These shares have a three-year cliff vesting.

2. Represents shares vested upon the third anniversary of the date of grant previously reported and are now issued and added to the reporting person's common stock holdings outright.

3. These shares are held in Mr. McLean's name outright.

4. These shares are held jointly with spouse.

	/s/ Shirley Cantrell, Attorney-in-Fact	02/24/2026
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider transactions did OSBC director Hugh H. McLean report on this Form 4?

Hugh H. McLean reported a grant of restricted stock units and a related tax-withholding disposition. He received 3,121 restricted stock units, then 3,077 units were used to satisfy tax obligations when earlier awards vested and converted into common shares.

How many restricted stock units were granted to OSBC director Hugh H. McLean?

McLean was granted 3,121 restricted stock units at a price of $0.00 per unit. These units were issued under Old Second Bancorp, Inc.’s Long Term Incentive Plan and are subject to a three-year cliff vesting schedule before converting into common stock.

What was the size and price of the tax-withholding disposition reported by OSBC’s director?

The filing shows a tax-withholding disposition of 3,077 restricted stock units at $20.57 per share. This transaction satisfied tax obligations when previously granted awards vested and the corresponding common shares were issued and added to Hugh H. McLean’s holdings.

What are the vesting terms of the restricted stock units granted to OSBC director Hugh H. McLean?

The restricted stock units granted to McLean have a three-year cliff vesting schedule. This means none of the units vest until the third anniversary of the grant date, at which time they vest in full and convert into Old Second Bancorp, Inc. common shares.

How many Old Second Bancorp restricted stock units and common shares does Hugh H. McLean hold after these transactions?

After the reported transactions, McLean directly holds 10,595 restricted stock units and 157,274 shares of Old Second Bancorp, Inc. common stock. Some of these shares are noted as being held outright and some jointly with his spouse, according to the filing footnotes.