** Shares of regional bank First Interstate Bancsystem
FIBK.O fall as much as 3.5%, last down 3.2% at $25.16
** The bank on Friday announced the upcoming retirement of
its CEO Kevin Riley
** Riley, who has been the CEO since 2015, will continue to
serve in his role until the $30 bln bank appoints a successor
** Stephens says it found the news surprising and believes
most investors likely had a similar reaction
** Adds that it is pleased to see the departure is not
immediate, but the duration of the executive search will remain
a focal point in the story over the near term
** Brokerage says it won't be surprised to see buyout
speculation increase
(Reporting by Arasu Kannagi Basil in Bengaluru)
((ArasuKannagi.Basil@thomsonreuters.com;))