Old Second director sells 25K OSBC shares

Old Second Bancorp director reports a 25,000-share sale and now directly holds 135,351 OSBC shares plus 10,595 RSUs.

Rhea-AI Filing Summary

OLD SECOND BANCORP INC (OSBC) director Hugh H. McLean reported selling 25,000 shares of Old Second Bancorp, Inc. common stock on September 3, 2026, at $25.727 per share in an open-market or private transaction. After this activity and an internal transfer of 3,077 shares to his brokerage account, he directly holds 135,351 common shares and 10,595 Restricted Stock Units.

Insider Trade Summary

Net Seller: 25,000 shares

Net Sell 2 txns

Insider MCLEAN HUGH H

Role Director

Sold 25,000 shs ($643K)

Type	Security	Shares	Price	Value
Sale	Old Second Bancorp, Inc. Common Stock F1	25,000	$25.727	$643K
holding	Restricted Stock Units	--	--	--

Holdings After Transaction: Old Second Bancorp, Inc. Common Stock — 135,351 shares (Direct); Restricted Stock Units — 10,595 shares (Direct)

Footnotes (1)

1. F1. The reporting person moved 3,077 shares that were previously held in his account from within Old Second Bancorp, Inc., as reported on a Form 4 filing dated February 24, 2026, to his brokerage account. The total shown reflects the addition of the 3,077 shares when combined with the sale of 25,000 shares.

Key Figures

Shares sold: 25,000 shares Sale price per share: $25.727 per share Common shares owned after transaction: 135,351 shares +2 more

5 metrics

Shares sold 25,000 shares Sale of Old Second Bancorp, Inc. common stock on September 3, 2026

Sale price per share $25.727 per share Price for the 25,000-share sale on September 3, 2026

Common shares owned after transaction 135,351 shares Directly held by Hugh H. McLean after the reported sale and share move

Restricted Stock Units held 10,595 RSUs Direct RSU holdings reported as of September 3, 2026

Shares moved between accounts 3,077 shares Moved from an account within Old Second Bancorp, Inc. to a brokerage account, included in the post-transaction total

Key Terms

Restricted Stock Units, open market or private transaction, brokerage account

3 terms

Restricted Stock Units financial

"The Form 4 shows that Hugh H. McLean directly holds 10,595 Restricted Stock Units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

open market or private transaction financial

"Sale in open market or private transaction for 25,000 shares at $25.727"

brokerage account financial

"3,077 shares were moved to his brokerage account and included in the total"

FAQ

What insider transaction did OSBC director Hugh H. McLean report?

He reported a sale of 25,000 shares of Old Second Bancorp, Inc. common stock on September 3, 2026 at $25.727 per share in an open-market or private transaction.

How many OSBC shares does Hugh H. McLean own after this Form 4?

Following the reported activity, Hugh H. McLean directly holds 135,351 shares of Old Second Bancorp, Inc. common stock, as well as 10,595 Restricted Stock Units.

Was the OSBC insider’s 25,000-share sale under a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is marked as false, and there is no footnote stating that the 25,000-share sale on September 3, 2026 was made under a Rule 10b5-1 trading plan.

What does the 3,077-share reference mean in the OSBC Form 4 footnote?

A footnote states that 3,077 shares previously held in an account within Old Second Bancorp, Inc. were moved to Hugh H. McLean’s brokerage account, and that the 135,351-share total reflects this addition together with the 25,000-share sale.

What derivative or RSU holdings does the OSBC director report?

The Form 4 shows that Hugh H. McLean directly holds 10,595 Restricted Stock Units after the reported date of September 3, 2026. No other derivative positions are listed in this filing.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/03/2026 - 05:47 PM Accepted by SEC EDGAR 09/03/2026 - 05:40 PM Learn about SEC filing dates

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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 ILLINOIS 60126

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/03/2026

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

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

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

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	09/03/2026		S		25,000	D	$25.727	135,351(1)	D
Restricted Stock Units								10,595	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. The reporting person moved 3,077 shares that were previously held in his account from within Old Second Bancorp, Inc., as reported on a Form 4 filing dated February 24, 2026, to his brokerage account. The total shown reflects the addition of the 3,077 shares when combined with the sale of 25,000 shares.

	/s/ Shirley Cantrell, Attorney-in-Fact	09/03/2026
	** 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)