UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

Current Report

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):  March 26, 2014

Old Second Bancorp, Inc.
(Exact name of registrant as specified in its charter)

37 South River Street
Aurora, Illinois  60507
(Address of principal executive offices) (Zip code)

(630) 892-0202
(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o            Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o            Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o            Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o            Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 7.01. Regulation FD Disclosure.

On March 26, 2014, Old Second Bancorp, Inc. (the “Company”), issued a press release announcing its commencement of marketing efforts in connection with its underwritten public offering of 13,500,000 shares of newly issued common stock, to be offered pursuant to a registration statement filed with the Securities and Exchange Commission.

A copy of the press release is furnished herewith as Exhibit 99.1 to this Current Report on Form 8-K.  Pursuant to the rules and regulations of the Securities and Exchange Commission, such exhibit and the information set forth therein and herein are deemed to be furnished and shall not be deemed to be “filed” under the Securities Exchange Act of 1934, as amended.

Item 9.01.                                        Financial Statements and Exhibits.

(d)                                 Exhibits.  The following exhibits are filed herewith:

99.1                        Press release issued by the Company on March 26, 2014

The information contained in this Form 8-K pursuant to Item 7.01 and the materials filed as exhibits shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any offer or sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. A registration statement relating to these securities has been filed with the Securities and Exchange Commission but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective.

2

Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

3