Cincinnati, Ohio — Two Midwestern-based banks announced Tuesday that their companies had received shareholder approval to move forward with a proposed merger.

MainSource Financial Group, based in Greensburg, and First Financial Bancorp, based in Cincinnati, announced July 25 their plans to merge.

MainSource Bank will merge into First Financial Bank in a transaction valued at about $1 billion, the initial announcement said. The merger is expected to close in early 2018, subject to all required regulatory approvals, the companies said.

Upon completion of the merger, First Financial Bank will be the surviving entity, according to a news release Tuesday afternoon from the companies. MainSource Bank branches will continue to operate under their current name until the conversion of their operating systems, expected in the second quarter of 2018, the companies said.

Combined, the bank is anticipated to become the sixth largest bank in deposit market share in Indiana.

Upon closing, First Financial shareholders would own about 63 percent of the combined company and MainSource shareholders would own 37 percent, the original merger announcement said.

The combined company will be headquartered in Cincinnati, primarily serving customers in Ohio, Indiana and Kentucky.

First Financial has 102 banking centers in Ohio, Kentucky and Indiana, including five in the Columbus area: 125 Third St., 707 Creekview, 3950 Jonathan Moore Pike and 2531 Eastbrook Plaza in Columbus; and 2070 N. State St. in North Vernon.

MainSource Financial Group operates 101 banking centers. Its Columbus area offices are located at 1901 25th St., 529 Washington St., and 2310 W. Jonathan Moore Pike in Columbus; plus 3880 W. Presidential Way in Edinburgh, 8475 State Road 9 in Hope and 102 Underwood Drive in Westport.