Diamond Bancorp’s banking subsidiary manages four bank offices located in Chicago, Schaumburg, Elmhurst and Northbrook, Illinois and had almost $165m in assets and about $135m in deposits, as of 30 June 2013.

Wintrust president and CEO Edward Wehmer said, "This transaction provides a great opportunity to expand our presence on the north side of the city of Chicago and to supplement our suburban franchise."

Diamond Bank president Matthew Gambs added, "the transaction allows us to continue focusing on serving our customers, while at the same time providing our customers with access to a wider range of products and services."

Based on the terms of the merger agreement, outstanding shares of Diamond common stock outstanding will be converted into the right to receive cash merger consideration.

The transaction, which is expected to close by early in the fourth quarter of 2013, is subject to approval by concerned banking regulators and the satisfaction of certain closing conditions.

Having assets of nearly $18bn, Wintrust operates as a financial holding company and manages 15 community bank subsidiaries, with over 115 banking locations located in the greater Chicago and Milwaukee market areas.