Company: OSBC
Filing Date: 2025-04-23
Form Type: S-4
Source: 0001104659-25-037832
Chunk: 410

Company: OLD SECOND BANCORP INC
Filing Date: 2025-04-23
Form: S-4
Chunk 410
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 this Agreement be given their fair and literal meaning, and that this Agreement is not to be strictly construed against any party, including the drafter of this Agreement. The Parties hereto acknowledge that DuPage County, Illinois**

<div align='center'>C-1-21</div>

TABLE OF CONTENTS

is a convenient forum, agree that any controversy or claim relating to this Agreement shall be brought in State or Federal Court in and for DuPage County, Illinois and therefore submit to the personal jurisdiction of such courts. IN WITNESS WHEREOF, the parties have executed this Agreement to be effective as of the Effective Date.

| ​ | OLD SECOND BANCORP, INC. |   |   |                                  | ​ | ​ | DARIN CAMPBELL |   |   |   | ​ |
| ​ | By:                      | ​ | ​ | ​                                | ​ | ​ | By:            | ​ | ​ | ​ | ​ |
| ​ | ​                        | ​ | ​ | Chris Lasse, SVP Human Resources | ​ | ​ | ​              | ​ | ​ | ​ | ​ |
| ​ | Date:                    | ​ | ​ | ​                                | ​ | ​ | Date:          | ​ | ​ | ​ | ​ |

C-1-22

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#### Annex B​
February 18, 2025

The Board of Directors 
 Bancorp Financial, Inc. 
 1515 West 22 nd Street 
 Suite 100 West 
 Oak Brook, IL 60523

Members of the Board:

You have requested the opinion of Keefe, Bruyette & Woods, Inc. (“KBW” or “we”) as investment bankers as to the fairness, from a financial point of view, to the common stockholders of Bancorp Financial, Inc. (“Bancorp Financial”) of the Merger Consideration (as defined below) to be received by such stockholders in the proposed merger of Bancorp Financial with and into Old Second Bancorp, Inc. (“Old Second”) (such merger, the “Merger”), pursuant to the Agreement and Plan of Merger (the “Agreement”) to be entered into by and between Bancorp Financial and Old Second. Pursuant to the Agreement and subject to the terms, conditions and limitations set forth therein, at the Effective Time (as defined in the Agreement), by virtue of the Merger and without any action on the part of Old Second, Bancorp Financial or the stockholders of either