Great Western Bancorp, Inc. Announces Updated Earnings Date for the Quarter Ending on September 30, 2021

Great Western Bancorp, Inc. (NYSE:GWB), the parent company of Great Western Bank (www.greatwesternbank.com), announced today that it will release financial results for the quarter ending on September 30, 2021 on Tuesday, October 26, 2021. Given the pending merger with First Interstate BancSystem, Inc. (NASDAQ: FIBK), this modified date coincides with the FIBK's earnings release on October 27, 2021, and the Company will not be conducting an earnings conference call this quarter. The press release and the slide presentation relating to the Company's earnings results will be available on the Company's Investor Relations website, ir.greatwesternbank.com.

About Great Western Bancorp, Inc.

Great Western Bancorp, Inc. is the holding company for Great Western Bank, a full-service regional bank focused on relationship-based business and agribusiness banking. Great Western Bank offers small and mid-sized businesses a focused suite of financial products and a range of deposit and loan products to retail customers through several channels, including the branch network, online banking system, mobile banking applications and customer care centers. The bank services its customers through more than 170 branches in nine states: Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota. To learn more about Great Western Bank visit www.greatwesternbank.com.

Forward Looking Statements

The materials posted may contain forward-looking statements, including guidance, involving significant risks and uncertainties, which will be identified by words such as "believe," "expect," "anticipate," "intend," "estimate," "should," "is likely," "will," "going forward" and other expressions that indicate future events and trends and may be followed by or reference cautionary statements. A number of factors could cause actual results to differ materially from those in the forward-looking information. These factors are outlined in our most recent earnings press release and in more detail in our most current 10-Q and 10-K filings. Great Western Bancorp, Inc. disclaims any obligation to update any of the forward-looking statements that are made from time to time to reflect future events or developments or changes in expectations.