Company: OSBC
Filing Date: 2025-05-08
Form Type: 424B3
Source: 0001104659-25-046065
Chunk: 9

Company: OLD SECOND BANCORP INC
Filing Date: 2025-05-08
Form: 424B3
Chunk 9
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/prospectus contains information about Old Second and its common stock.

Q: What will Bancorp Financial stockholders receive in the merger?**

A:

If the merger is completed, each outstanding share of Bancorp Financial common stock (except for treasury stock or shares owned by Old Second and Bancorp Financial, in each case, other than shares held on behalf of third parties or as a result of debts previously contracted, and shares held by Bancorp Financial stockholders who properly exercise their appraisal rights) will be converted into the right to receive 2.5814 shares of Old Second common stock, which we refer to as the “exchange ratio,” and $15.93 in cash, without interest, which, together with the exchange ratio and any cash in lieu of fractional shares as discussed below, we refer to as the “merger consideration.”

Old Second will not issue any fractional shares of Old Second common stock in the merger. Instead, a Bancorp Financial stockholder who otherwise would have received a fraction of a share of Old Second common stock will receive an amount in cash equal to such fraction multiplied by the average closing

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price of Old Second common stock as quoted on NASDAQ during the five full trading days ending on and including the fifth trading day prior to the date the merger is consummated.

**Q:

Will the value of the merger consideration to Bancorp Financial stockholders change between the date of this proxy statement/prospectus and the time the merger is completed?**

#### A.
Yes. Although the exchange ratio is fixed, which means that it will not change between now and the date the merger is completed, the value of the stock component of the merger consideration is dependent upon the value of Old Second common stock and, therefore, will fluctuate with the market price of shares of Old Second common stock.

**Based on the closing price of Old Second common stock on February 24, 2025, the last trading day before public announcement of the merger, of $18.08 per share, the merger consideration represented approximately $62.60 in value for each share of Bancorp Financial common stock. Based on the closing price of Old Second common stock on May 7, 2025, the last practicable trading date before the date of this proxy statement/prospectus, of $16.36 per share, the merger consideration represented approximately $58.16 in value for each share of Bancorp Financial common stock. The market price of shares of Old Second