Company: OSBC
Filing Date: 2025-05-08
Form Type: 424B3
Source: 0001104659-25-046065
Chunk: 45

Company: OLD SECOND BANCORP INC
Filing Date: 2025-05-08
Form: 424B3
Chunk 45
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 the conditions to the closing is that no order, injunction or similar decree issued by any governmental authority of competent jurisdiction or other legal restraint will prohibit the consummation of the transactions contemplated by the merger agreement. If any plaintiff were successful in obtaining an injunction prohibiting the parties from completing the merger pursuant to the merger agreement, then such injunction may delay or prevent the effectiveness of the merger. If a lawsuit is filed, the parties may incur costs in connection with the defense or settlement of any such lawsuits, which could have an adverse effect on Old Second’s and/or Bancorp Financial’s financial condition and results of operations and could prevent or delay the completion of the merger.

Bancorp Financial stockholders may have appraisal rights in connection with the merger.

If the merger agreement is adopted by Bancorp Financial stockholders, those stockholders who do not vote in favor of the merger and who properly comply with all of the requirements of Section 262 of the DGCL may be entitled to receive payment in cash for the fair value of their shares, as determined by the Delaware Court of Chancery, instead of receiving the merger consideration. In addition, Old Second’s obligation to complete the merger is conditioned on holders of no more than 7.5% of the aggregate outstanding shares of Bancorp Financial common stock having properly notified Bancorp Financial of their intent to exercise appraisal rights. Neither Bancorp Financial nor Old Second can predict how many stockholders will seek appraisal. For more information, see “Bancorp Financial Stockholders’ Appraisal Rights.”

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TABLE OF CONTENTS

### Risks Relating to Old Second’s Business
You should read and consider risk factors specific to Old Second’s business that will also affect the combined company after the merger. These risks are described in the sections entitled “Risk Factors” in Old Second’s Annual Report on Form 10-K for the year ended December 31, 2024, and in other documents incorporated by reference into this proxy statement/prospectus. Please see the section entitled “Where You Can Find More Information” in the forepart of this proxy statement/prospectus and “Incorporation of Certain Documents by Reference” beginning on page 126 for the location of information incorporated by reference into this proxy statement/prospectus.

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### BANCORP FINANCIAL SPECIAL MEETING OF STOCKHOLDERS
Date, Time and Place of the Bancorp Financial Special Meeting

The Bancorp Financial special