Company: OSBC
Filing Date: 2025-05-08
Form Type: 424B3
Source: 0001104659-25-046065
Chunk: 177

Company: OLD SECOND BANCORP INC
Filing Date: 2025-05-08
Form: 424B3
Chunk 177
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The SEC’s rules permit companies and intermediaries (such as brokers) to deliver a single copy of this proxy statement/prospectus to multiple stockholders who share the same address, unless one or more of those stockholders has objected to householding. This practice is known as “householding.” Householding reduces printing and mailing costs and helps conserve environmental resources.

If you are a Bancorp Financial stockholder and would like to receive a separate copy of this proxy statement/prospectus, please contact Bancorp Financial at:

1515 West 22nd Street, Suite 100W 
 Oak Brook, Illinois 60523 
 Attention: Corporate Secretary 
 (630) 413-9580

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### OTHER MATTERS
As of the date of this proxy statement/prospectus, the Bancorp Financial board of directors knows of no other matters that will be presented for consideration at its special meeting of stockholders, other than as described in this proxy statement/prospectus. If any other matters properly come before the Bancorp Financial special meeting, or any adjournment or postponement thereof, and are voted upon, the enclosed proxies will be deemed to confer discretionary authority on the individuals that it names as proxies to vote the shares represented by the proxies as to any of these matters.

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### OLD SECOND ANNUAL MEETING STOCKHOLDER PROPOSALS
A stockholder seeking to present any business at Old Second’s annual meeting of stockholders must submit a notice in writing to the Corporate Secretary, at 37 South River Street, Aurora, Illinois 60507, not earlier than 120 days and not later than 90 days prior to the first anniversary of the preceding year’s annual meeting; provided that, if the date of the annual meeting is moved to more than 30 days before or more than 60 days after the anniversary date of the previous year’s meeting, for notice by the stockholder to be timely it must be delivered to us not earlier than 120 days prior to the date of such annual meeting and not later than 90 days prior to the date of such annual meeting or, if the first public announcement of the date of such annual meeting is less than 100 days prior to the date of such annual meeting, then the tenth day following the day on which public announcement of the date of such meeting is first made by Old Second.

A stockholder seeking to include a proposal in Old Second’s proxy