** Microsoft-backed cybersecurity firm Rubrik's RBRK.N shares rise 20.7% to $66.75 premarket
** RBRK late on Thursday forecast Q1 revenue in the range of $259 million to $261 million vs analysts' estimate of $246.12 million, according to data compiled by LSEG
** Co posted Q4 revenue of $258.1 million vs analysts' average estimate of $233.10 million
** RBRK up 49.4% since its Nasdaq debut last April
(Reporting by Padmanabhan Ananthan)
((Padmanabhan.Ananthan@thomsonreuters.com;))