First Interstate BancSystem, Inc. (NASDAQ: FIBK)(“First Interstate”), parent company of First Interstate Bank, and Mountain West Financial Corp. (OTCBB: MTWF)(“Mountain West”), parent company of Mountain West Bank, National Association announced today that First Interstate has signed a definitive agreement to acquire the Helena-based Mountain West. With assets of $647 million, as of September 30, 2013, Mountain West Bank currently operates 12 branches throughout central and western Montana in Helena, Great Falls, Missoula, Kalispell, Whitefish, and Bozeman. “Like First Interstate Bank, Mountain West Bank is a community bank whose success has been built on a foundation of commitment to its customers and communities,” said Tom Scott, Chairman of First Interstate. “Bringing these two companies together gives us the opportunity to expand our state-wide market in Montana and provides us with a solid presence in the Helena Market. We’re confident this acquisition will create long-term value for both companies: our customers, our employees, our shareholders and our communities.” First Interstate President and CEO Ed Garding added, “We are excited about the possibilities created through the combination of our two companies and are honored to have Mountain West become a part of our organization. They’ve worked hard to create a strong franchise and are a recognized leader in the Helena community and the other communities they serve across Montana.” “We are delighted to be joining the First Interstate organization,” said Rick Hart, CEO of Mountain West. “With First Interstate Bank, our customers will benefit from an expanded line of financial services and innovative solutions, while continuing to benefit from personalized service and local decision-making. Our customers, employees and shareholders will be joining a company where people can be proud to bank, proud to work and proud to invest.” Pursuant to the terms of the definitive merger agreement, Mountain West shareholders will receive 0.2552 shares of First Interstate Class A common stock plus $7.125 in cash in exchange for each share of Mountain West common stock they hold. Mountain West shareholders will be allowed to elect, subject to allocation procedures, to receive their specific merger consideration in all stock or all cash in amounts intended to be substantially equal in value to the above described combination of both stock and cash for each share of Mountain West common stock. The value received by Mountain West shareholders will fluctuate based on First Interstate’s stock price. Based on First Interstate’s closing stock price of $24.77 February 10, 2014, Mountain West shareholders would have received consideration value at approximately $13.45 per share, with a total value paid to Mountain West shareholders and option holders of approximately $72.8 million.