First Interstate BancSystem(FIBK) - 2018 Q4 - Annual Report

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington D.C. 20549 FORM 10-K (Mark One) þ Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the fiscal year ended December 31, 2018 or o Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-34653 FIRST INTERSTATE BANCSYSTEM, INC. (Exact name of registrant as specified in its charter) Montana (State or other jurisdiction ...