# EDGAR Filing Document

**Accession Number:** 0000357173
**File Stem:** 0000357173-26-000024
**Filing Date:** 2026-5
**Character Count:** 6027
**Document Hash:** 9e9d12aee4ec0ceb4078c04e10bf0177
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000357173-26-000024.hdr.sgml**: 20260519

**ACCESSION NUMBER**: 0000357173-26-000024

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 14

**CONFORMED PERIOD OF REPORT**: 20260519

**ITEM INFORMATION**: Regulation FD Disclosure

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260519

**DATE AS OF CHANGE**: 20260519

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** OLD SECOND BANCORP INC
- **CENTRAL INDEX KEY:** 0000357173
- **STANDARD INDUSTRIAL CLASSIFICATION:** STATE COMMERCIAL BANKS [6022]
- **ORGANIZATION NAME:** 02 Finance
- **EIN:** 363143493
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-10537
- **FILM NUMBER:** 26996323

**BUSINESS ADDRESS:**
- **STREET 1:** 37 S RIVER ST
- **CITY:** AURORA
- **STATE:** IL
- **ZIP:** 60507
- **BUSINESS PHONE:** 6308920202

**MAIL ADDRESS:**
- **STREET 1:** 37 SOUTH RIVER STREET
- **CITY:** AURORA
- **STATE:** IL
- **ZIP:** 60507

?xml version='1.0' encoding='ASCII'? OLD SECOND BANCORP INC_May 19, 2026

I

**United States**

**Securities And Exchange Commission**

**Washington, D.C. 20549**

**FORM 8-K**

**Current Report**

#### Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
Date of Report (Date of earliest event reported): **May 19, 2026**

![Graphic](osbc-20260519x8k001.jpg)

(Exact name of registrant as specified in its charter)

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**Delaware** | &nbsp;&nbsp;**000-10537** | &nbsp;&nbsp;**36-3143493** |
| &nbsp;&nbsp;(State or other jurisdiction of incorporation) | &nbsp;&nbsp;(Commission File Number) | &nbsp;&nbsp;(I.R.S. Employer Identification No.) |

---

**37 South River StreetAurora, Illinois 60507**(Address of principal executive offices) (Zip code)

#### (630) 892-0202 (Registrant's telephone number, including area code)
**N/A**

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (*see* General Instruction A.2. below):

**☐** Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

**☐** Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

**☐** Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

**☐** Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

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| | | |
|:---|:---|:---|
| **Title of each class** | **Trading Symbol(s)** | **Name of each exchange on which registered** |
| Common Stock | OSBC | The Nasdaq Stock Market |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 under the Securities Act (17 CFR 230.405) or Rule 12b-2 under the Exchange Act (17 CFR 240.12b-2).

Emerging growth company **☐**

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. **☐**

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**Item 7.01 Regulation FD Disclosure**

On May 19, 2026, a presentation was made at the Annual Stockholders Meeting. Details of how to access the Annual Stockholders Meeting presentation materials are attached as Exhibit 99.1 to this report and such presentation announcement is incorporated herein by reference.

The information in this Form 8-K and the Exhibit attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Act of 1934, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, except as shall be expressly set forth by specific reference.

**Item 9.01 Exhibits.**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(d) Exhibits

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[99.1 – Shareholder Presentation Announcement.](osbc-20260519xex99d1.htm)

**Signature**

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

---

| | | |
|:---|:---|:---|
|  | **OLD SECOND BANCORP, INC.** | **OLD SECOND BANCORP, INC.** |
| Dated: May 19, 2026 | By: | /s/ Bradley S. Adams |
|  |  | Bradley S. Adams |
|  |  | Executive Vice President, |
|  |  | Chief Operating Officer and |
|  |  | Chief Financial Officer |

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## Exhibit 99.1

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| | | |
|:---|:---|:---|
| **(NASDAQ:OSBC)** | **(NASDAQ:OSBC)** | **Exhibit 99.1** |
| **Contact:** | **Bradley S. Adams** | **For Immediate Release** |
|  | **Executive Vice President,** | **May 19, 2026** |
|  | **Chief Operating Officer and**<br>**Chief Financial Officer**<br>**(630) 906-5484** |  |

---

**Old Second Bancorp, Inc. Annual Stockholders Meeting**

**AURORA, IL, –** Old Second Bancorp, Inc. ("Old Second") (NASDAQ: OSBC), announced the Annual Stockholders Meeting will be held on May 19, 2026 at 9:00 am CDT.

Shareholders and investors may access the presentation made at the meeting under the Presentations tab on the Investor Relations section of Old Second's website (www.oldsecond.com).

**About Old Second Bancorp, Inc.**

Old Second Bancorp, Inc., is a financial services company with its main headquarters located in Aurora, Illinois. The Company is the holding company of Old Second National Bank (the "Bank"), a national banking organization headquartered in Aurora, Illinois that provides commercial and retail banking services, as well as a full complement of trust and wealth management services. The Company has offices located in Cook, DeKalb, DuPage, Kane, Kendall, LaSalle and Will counties in Illinois.

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