** Cybersecurity firm SecureWorks shares fall 1.5% to $8.35

** U.K.-based Sophos said it will acquire SCWX from DELL for $859 mln

** Shareholders will receive $8.50/share, whereas last close was $8.47

** Before this deal, owner Dell Technologies explored sale of SCWX in 2019, with a then market value of close to $2 bln

** Including session's move, SCWX is up ~13% this year

(Reporting by Rishi Kant in Bengaluru)

((Rishi.Kant@thomsonreuters.com))