Zscaler rises after Mizuho upgrades rating to 'outperform'
** Cloud security firm Zscaler's ZS.O shares rise 1.7% to $234.25 premarket ** Mizuho upgrades rating to "outperform" from "neutral" ** Brokerage confident that ZS is well-positioned in Secure Access Service Edge and Zero Trust markets ** Average rating of 48 analysts is "buy"; median PT is $330.45 - data compiled by LSEG ** As of last close, stock up 27.7% this year (Reporting by Anhata Rooprai in Bengaluru) ((Anhata.Rooprai@thomsonreuters.com))