First Security Bank

First Security Bank Montana First Security Bank is a division of Glacier Bank based in Bozeman, Montana. It is the area's largest bank in deposit market share and number of locations. First Security serves Gallatin County. The bank has branches in Bozeman, Belgrade, Three Forks, Big Sky, West Yellowstone, and Four Corners. First Security Bank is one of the top employers in Gallatin County and was recognized as Montana's Employer of Choice (over 25 employees) in 2013 by the Montana State Employer's Council (MSEC).