** Intuitive Surgical ISRG.O falls 2.7% to $542 premarket
** Deutsche Bank downgrades co to "sell" from "hold", cuts PT to $440 from $515
** Stock rated "buy" on avg; median PT is $590, per LSEG-compiled data
** As of last close, ISRG up 6.7% this year
(Reporting by Twesha Dikshit)
((Twesha.Dikshit@thomsonreuters.com))