Dubuque-based Heartland Financial USA Inc. plans to buy Signature Bancshares Inc. of Minnetonka, Minn., according to a release. The acquisition is Heartland’s 20th since 1994 and its 13th transaction in the past six years. Signature Bank is a commercial and private bank with about $390 million in total assets, $326 million in net loans outstanding and $339 million in deposits as of Sept. 30. Signature Bank will be merged into Heartland’s Minnesota-based subsidiary, Minnesota Bank & Trust, with the combined organization operating as Minnesota Bank & Trust. Together Signature Bank and Minnesota Bank & Trust will have more than $600 million in combined assets and operate as one of Heartland’s locally managed subsidiary banks. Based on Heartland’s closing common stock price of $47.30 per share on Nov. 10, the stock and cash transaction is valued at about $53.4 million, including the consideration to be paid in exchange for the termination of Signature options, subject to certain adjustments. The actual transaction value will change due to fluctuations in the price of Heartland common stock. After the closing of the acquisition of Signature in the first quarter of 2018, Heartland will have 118 full-service banking locations in 12 states.