Old Second Bancorp CFO acquires 28 shares via 401(k)

The 401-k Plan's reported position following the allocation was 10,221 shares, separate from Adams's direct shares and restricted stock units.

Rhea-AI Filing Summary

Old Second Bancorp Inc. CFO & COO Bradley S. Adams reported an acquisition of 28 common shares on September 30, 2026. The shares were allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust and held indirectly through the 401-k Plan; the reported post-transaction position in that plan was 10,221 shares. Adams also reported 160,401 directly held common shares, including 75,300 held jointly with his spouse with a broker and 85,101 held jointly with his spouse outright, plus 84,980 restricted stock units.

Insider Trade Summary

Other: 28 shares

Other 3 txns

Insider ADAMS BRADLEY S.

Role CFO & COO

Type	Security	Shares	Price	Value
Other	Old Second Bancorp, Inc. Common Stock F1	28	$0.00	$0.00
holding	Old Second Bancorp, Inc. Common Stock F2	--	--	--
holding	Restricted Stock Units	--	--	--

Holdings After Transaction: Old Second Bancorp, Inc. Common Stock — 10,221 shares (Indirect, By 401-k Plan); Old Second Bancorp, Inc. Common Stock — 160,401 shares (Direct); Restricted Stock Units — 84,980 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. Included in this total are 75,300 shares held jointly with spouse with a broker and 85,101 shares held jointly with spouse outright.

Key Figures

Common shares allocated: 28 shares Shares held by 401-k Plan: 10,221 shares Direct common shares: 160,401 shares +3 more

6 metrics

Common shares allocated 28 shares Allocated during the third quarter of 2026

Shares held by 401-k Plan 10,221 shares Reported following the September 30, 2026 transaction

Direct common shares 160,401 shares Reported as of September 30, 2026

Restricted Stock Units 84,980 units Reported as of September 30, 2026

Shares held jointly with spouse with a broker 75,300 shares Included in the reported direct common shares

Shares held jointly with spouse outright 85,101 shares Included in the reported direct common shares

Key Terms

Employee Savings Plan & Trust, 401-k Plan, Restricted Stock Units

3 terms

Employee Savings Plan & Trust financial

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

401-k Plan financial

"By 401-k 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 Bradley S. Adams acquire?

Bradley S. Adams had 28 common shares allocated during the third quarter pursuant to the Old Second Bancorp, Inc. Employee Savings Plan & Trust.

What did Bradley S. Adams's direct OSBC share total include?

The 160,401 directly held common shares included 75,300 held jointly with his spouse with a broker and 85,101 held jointly with his spouse outright.

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

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Available on EDGAR 10/01/2026 - 02:24 PM Accepted by SEC EDGAR 10/01/2026 - 02:24 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^*

ADAMS BRADLEY S.

(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)
	CFO & COO

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		28(1)	A	$0	10,221	I	By 401-k Plan
Old Second Bancorp, Inc. Common Stock								160,401(2)	D
Restricted Stock Units								84,980	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. Included in this total are 75,300 shares held jointly with spouse with a broker and 85,101 shares held jointly with spouse outright.

	/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)