Company: OSBC
Filing Date: 2025-05-06
Form Type: S-4/A
Source: 0001104659-25-045103
Chunk: 53

Company: OLD SECOND BANCORP INC
Filing Date: 2025-05-06
Form: S-4/A
Chunk 53
---
aries for their reasonable expenses incurred in forwarding the proxy materials. These costs will also be subject to the 50/50 cost-sharing arrangement with Old Second.

#### Assistance
If you need assistance in completing your proxy card, have questions regarding the Bancorp Financial special meeting or would like additional copies of this proxy statement/prospectus, please contact our Corporate Secretary, Mr. Michael Spaniak, at (630) 413-9580.

<div align='center'>31</div>

TABLE OF CONTENTS

### BANCORP FINANCIAL PROPOSALS

#### Proposal 1 — Adoption of the Merger Agreement
**As discussed elsewhere in this proxy statement/prospectus, Bancorp Financial stockholders are being asked to approve the merger proposal, which provides for the merger of Bancorp Financial with and into Old Second in accordance with the terms of the merger agreement. Under Delaware law, the approval of the merger agreement by the holders of a majority of the outstanding shares of Bancorp Financial common stock entitled to vote is required in order to complete the merger. If stockholders do not approve the merger proposal, the merger will not be completed.

Bancorp Financial stockholders may vote on the merger proposal by submitting a valid proxy or timely casting a vote via the Internet, as described above, in advance of the meeting. Stockholders may also vote by attending the special meeting and voting live at the meeting. Stockholders are encouraged to carefully read this proxy statement/prospectus in its entirety, including the merger agreement, which is attached as Annex A, for a more detailed description of the terms and conditions of the merger and the other transactions contemplated by the merger agreement.

After careful consideration, the Bancorp Financial board of directors has unanimously determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable, fair to, and in the best interests of Bancorp Financial and its stockholders.

The Bancorp Financial board of directors unanimously recommends that Bancorp Financial stockholders vote “FOR” the merger proposal.

Proposal 2 — Amendment to the Bancorp Financial Stockholders Agreement**

### Background
Bancorp Financial is party to that certain Stockholders Agreement effective as of February 14, 2007 (the “Stockholders Agreement”), by and among Bancorp Financial and certain of its stockholders. The Stockholders Agreement provides that it may be amended by the mutual consent of Bancorp Financial and stockholders holding at least 66 2 ∕ 3 % of the outstanding common stock of Banc