A list of Montanan companies. Many well known Montana companies have been included. While this list isn't definitive, these are most of the top businesses in the state of Montana. As a country, the United States has encouraged entrepreneurship throughout much of its history. The state of Montana is no exception to this rule, and new businesses are started in Montana daily, ranging from corporations to LLCs to partnerships to sole proprietorships. This list, however, is mostly focused on the largest corporations in the state of Montana.