SHAREHOLDER ALERT: Rigrodsky Law, P.A. Announces Investigation of Great Western Bancorp, Inc. Merger

announces that it is investigating Great Western Bancorp, Inc. (GWB) (NYSE: GWB ) regarding possible breaches of fiduciary duties and other violations of law related to GWBs agreement to be acquired by First Interstate BancSystem, Inc. (First Interstate) (NASDAQ GS: FIBK ).