Banks in Big Sky, Montana, the US. Banks locations in Big Sky, Montana. Find the nearest banks locations, near you. All types of business services Accounting ATM Bank Finance Insurance Lawyer Real estate Travel All banks in Big Sky Closed now American Bank ATM Finance Bank +1 406-995-7111 1700 Lone Mountain Trail, Big Sky, Montana 59716 Write a review Phone Hours Website Directions Closed now First Security Bank ATM Finance Bank +1 406-993-3350 78 Meadow Village Drive, Big Sky, Montana 59716 Write a review Phone Hours Website Directions