Old Second Bancorp (OSBC) EVP Donald Pilmer sells 25,000 common shares

Rhea-AI Filing Summary

OLD SECOND BANCORP INC executive Donald Pilmer reported an open-market sale of 25,000 shares of Old Second Bancorp, Inc. common stock at an average price of $20.7518 per share. After this sale, he directly holds 48,054 common shares. The filing also shows 39,498 restricted stock units, plus indirect holdings of 1,450 shares in a spouse's IRA, 183 shares in a profit sharing plan, and 4,023 shares in a 401-K plan.

Insider Trade Summary

Net Seller: 25,000 shares ($518,795)

Net Sell 5 txns

Insider Pilmer Donald

Role EVP

Sold 25,000 shs ($519K)

Type	Security	Shares	Price	Value
Sale	Old Second Bancorp, Inc. Common Stock	25,000	$20.7518	$519K
holding	Old Second Bancorp, Inc. Common Stock	--	--	--
holding	Old Second Bancorp, Inc. Common Stock	--	--	--
holding	Old Second Bancorp, Inc. Common Stock	--	--	--
holding	Restricted Stock Units	--	--	--

Holdings After Transaction: Old Second Bancorp, Inc. Common Stock — 48,054 shares (Direct, null); Old Second Bancorp, Inc. Common Stock — 4,023 shares (Indirect, By 401-K Plan); Restricted Stock Units — 39,498 shares (Direct, null)

Footnotes (1)

1. Of this total, 23 shares were allocated during the second quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. Information herein was provided by the Plan Trustee as of 06-30-21. These shares are held in spouse's IRA for which Mr. Pilmer is listed as a beneficiary.

Key Figures

Shares sold: 25,000 shares Sale price: $20.7518 per share Direct holdings after sale: 48,054 shares +4 more

7 metrics

Shares sold 25,000 shares Open-market sale of common stock

Sale price $20.7518 per share Average price for 25,000-share sale

Direct holdings after sale 48,054 shares Common stock directly owned post-transaction

Restricted stock units 39,498 units RSUs reported as of transaction date

Spouse's IRA holdings 1,450 shares Indirect ownership via spouse's IRA

Profit sharing plan holdings 183 shares Indirect ownership via profit sharing plan

401-K plan holdings 4,023 shares Indirect ownership via 401-K plan

Key Terms

Restricted Stock Units, open-market sale, Spouse's IRA, Profit Sharing Plan, +1 more

5 terms

Restricted Stock Units financial

"security_title: "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 sale financial

"transaction_action: "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

Spouse's IRA financial

"nature_of_ownership: "Spouse's IRA""

Profit Sharing Plan financial

"nature_of_ownership: "By Profit Sharing Plan""

401-K Plan financial

"nature_of_ownership: "By 401-K Plan""

Form 4 Insider Transactions: What Each Field Means →

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)
05/11/2026

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	05/11/2026		S		25,000	D	$20.7518	48,054	D
Old Second Bancorp, Inc. Common Stock								4,023(1)	I	By 401-K Plan
Old Second Bancorp, Inc. Common Stock								183	I	By Profit Sharing Plan
Old Second Bancorp, Inc. Common Stock								1,450(2)	I	Spouse's IRA
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. Of this total, 23 shares were allocated during the second quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust. Information herein was provided by the Plan Trustee as of 06-30-21.

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

	/s/ Shirley Cantrell, Attorney-in-Fact	05/11/2026
	** 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)

FAQ

What insider transaction did OSBC executive Donald Pilmer report?

Donald Pilmer reported selling 25,000 shares of Old Second Bancorp, Inc. common stock in an open-market transaction at $20.7518 per share. The Form 4 also updates his remaining direct and indirect share and restricted stock unit holdings.

At what price did Donald Pilmer sell Old Second Bancorp (OSBC) shares?

He sold 25,000 shares of Old Second Bancorp, Inc. common stock at an average price of $20.7518 per share. This was reported as an open-market sale, classified under transaction code S in the insider filing.

How many OSBC shares does Donald Pilmer hold directly after the reported sale?

Following the 25,000-share sale, Donald Pilmer holds 48,054 shares of Old Second Bancorp, Inc. common stock directly. The filing separates these direct holdings from his restricted stock units and several indirect positions in retirement and savings plans.

What restricted stock unit holdings does Donald Pilmer have in OSBC?

The filing lists 39,498 restricted stock units for Donald Pilmer as of the reported date. Restricted stock units represent a right to receive shares in the future, typically subject to vesting conditions and continued employment or performance requirements.

What indirect Old Second Bancorp (OSBC) holdings are reported for Donald Pilmer?

Indirect holdings include 1,450 shares in a spouse's IRA, 183 shares held by a profit sharing plan, and 4,023 shares held by a 401-K plan. These positions are reported as indirect ownership, separate from his direct share and restricted stock unit holdings.

What does the Form 4 say about Old Second Bancorp (OSBC) employee plan allocations?

A footnote explains that of a prior total, 23 shares were allocated during a second quarter under the Old Second Bancorp, Inc. Employee Savings Plan & Trust, with information provided by the plan trustee as of June 30, 2021.