Old Second Bancorp EVP Pilmer acquires 11 shares

Reported positions included 48,054 directly held common shares, 39,498 restricted stock units and shares held through plans and a spouse’s IRA.

Rhea-AI Filing Summary

Old Second Bancorp Inc. (OSBC) EVP Donald Pilmer reported an acquisition of 11 common shares allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. The 401-K Plan held 4,048 shares following the transaction. Other reported positions as of September 30, 2026 included 184 shares by the Profit Sharing Plan, 1,450 shares in his spouse’s IRA, where Pilmer is listed as a beneficiary, 48,054 directly held common shares, and 39,498 restricted stock units.

Insider Trade Summary

Other: 11 shares

Other 5 txns

Insider Pilmer Donald

Role EVP

Type	Security	Shares	Price	Value
Other	Old Second Bancorp, Inc. Common Stock F1	11	$0.00	$0.00
holding	Old Second Bancorp, Inc. Common Stock	--	--	--
holding	Old Second Bancorp, Inc. Common Stock F2	--	--	--
holding	Old Second Bancorp, Inc. Common Stock	--	--	--
holding	Restricted Stock Units	--	--	--

Holdings After Transaction: Old Second Bancorp, Inc. Common Stock — 4,048 shares (Indirect, By 401-K Plan); Old Second Bancorp, Inc. Common Stock — 184 shares (Indirect, By Profit Sharing Plan); Old Second Bancorp, Inc. Common Stock — 1,450 shares (Indirect, Spouse's IRA); Old Second Bancorp, Inc. Common Stock — 48,054 shares (Direct); Restricted Stock Units — 39,498 shares (Direct)

Footnotes (2)

1. F1. These shares were allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. Information herein was provided by the Plan Trustee as of 9-30-26.
2. F2. These shares are held in spouse's IRA for which Mr. Pilmer is listed as a beneficiary.

Key Figures

Shares allocated: 11 shares 401-K Plan shares following transaction: 4,048 shares Profit Sharing Plan shares: 184 shares +3 more

6 metrics

Shares allocated 11 shares Allocated during the third quarter under the Employee Savings Plan & Trust

401-K Plan shares following transaction 4,048 shares As of September 30, 2026

Profit Sharing Plan shares 184 shares As of September 30, 2026

Spouse’s IRA shares 1,450 shares As of September 30, 2026; Pilmer is listed as a beneficiary

Directly held common shares 48,054 shares As of September 30, 2026

Restricted stock units 39,498 units As of September 30, 2026

Key Terms

Employee Savings Plan & Trust, Profit Sharing Plan, Restricted Stock Units

3 terms

Employee Savings Plan & Trust financial

"pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust"

Profit Sharing Plan financial

"By Profit Sharing Plan"

Restricted Stock Units financial

"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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many OSBC shares did Donald Pilmer acquire?

Donald Pilmer reported an acquisition of 11 common shares, allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. The 401-K Plan held 4,048 shares following the transaction.

What OSBC shares and units did Donald Pilmer report holding?

As of September 30, 2026, reported positions included 48,054 directly held common shares, 39,498 restricted stock units, 184 shares by the Profit Sharing Plan and 1,450 shares in his spouse’s IRA, where he is listed as a beneficiary.

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

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Available on EDGAR 10/01/2026 - 02:18 PM Accepted by SEC EDGAR 10/01/2026 - 02:17 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^*

Pilmer Donald

(Last) (First) (Middle)

37 S. RIVER ST.

(Street)

AURORA ILLINOIS 60506

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/30/2026

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	09/30/2026		J		11(1)	A	$0	4,048	I	By 401-K Plan
Old Second Bancorp, Inc. Common Stock								184	I	By Profit Sharing Plan
Old Second Bancorp, Inc. Common Stock								1,450(2)	I	Spouse's IRA
Old Second Bancorp, Inc. Common Stock								48,054	D
Restricted Stock Units								39,498	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 shares were allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. Information herein was provided by the Plan Trustee as of 9-30-26.

2. These shares are held in spouse's IRA for which Mr. Pilmer is listed as a beneficiary.

	/s/ Shirley Cantrell, Attorney-in-Fact	10/01/2026
	** 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)