First Interstate BancSystem, Inc. Announces Quarterly Dividend Increase of 6% to $0.12 per Share

First Interstate BancSystem, Inc.'s

Executive Committee of the Board of Directors, at a meeting held on December 12, 2011, declared an increase of more than 6% in its quarterly dividend to $.12 per common share. The dividend is payable on January 17, 2012 to owners of record on January 3, 2012.