** Online grocer Ocado down 6.6 pct, 2nd top falleron Stoxx 600 & bottom of FTSE 250 as Exane BNPParibas cuts rating to "underperform" following Tuesday's marginpressure warning
** Brokerage expects H2 gross margins to fall, earningsprogression be short of market expectations
** Exane expects little net profit growth over 3-4 yrs
** Stock closed down about 11 pct on Tuesday
** 1.5x 30-day daily avg volume through in an hour
** 8 brokerages rate stock "buy" or higher, 4 "hold" & 3"sell"
** Up to Tuesday's close, stock -8.6 pct compared with +4.5pct on FTSE 350 Food & Drug Retailers index (Reuters Messaging:pranav.kiran@thomsonreuters.com@reuters.net)