As per the definitive agreement originally inked in January, the aggregate purchase price was determined at $38.5m, which will be paid through a grouping of 40% cash and almost 60% shares of Wintrust common stock.

Following completion of the transaction, FNBI will be merged into Wintrust’s wholly-owned subsidiary, Old Plank Trail Community Bank, while its banking locations will operate as branches of the latter.

Commenting on the acquisition, Wintrust president and CEO Edward Wehmer said, "This transaction provides a terrific opportunity to expand our presence in the southern part of our market area and helps us continue on our path to become Chicago’s Bank."

FNBI president Gilbert Rynberk emphasized that, "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."

Founded in 1945 and headquartered in Lansing, Illinois, US, FNBI manages seven bank branches in the south and southwest suburbs of Chicago, as well as one location in northwest Indiana.

Operating as a community bank, it had about $365m in assets and almost $323m in deposits, as of 31 March 2013.

With assets of approximately $17bn, Wintrust manages 15 community bank subsidiaries, now with over 100 banking locations located in the greater Chicago and Milwaukee market areas and offers personal and commercial banking services.