BUZZ-Zoopla, Rightmove: nerves creep in over OnTheMarket.com

** Zoopla & Rightmove under pressure as Panmure Gordon slaps "sell" ratings on the pair, arguing recently launched rival portal OnTheMarket.com (OTM) poses more of a threat than initially thought

** Zoopla nonetheless risen strongly this week - up more than 20 pct over Mon & Tues when mkt took view OTM launch was damp squib

** Panmure says OTM still looks flawed as a real challenger, but could be "noisy neighbour" for some time, can adapt business model, & will hurt incumbents' profits more than expected

** Broker expects UK property volumes to remain subdued for some time

** Also reckons RMV's current valuation already discounts there being no long-term impact from OTM

** Key concern about Zoopla was OTM's one other portal rule, whereby OTM participants were not to list on more than one other site, effectively making them choose between Zoopla & Rightmove; but press have reported rule largely being ignored

** Rightmove (LSE: RMV.L - news) , which Panmure downgrades to "sell" vs "buy", & Zoopla, which broker starts as "sell", top two FTSE 250 fallers, both down 3.4 pct in relatively strong volumes (RM (LSE: RM.L - news) : tricia.wright1.thomsonreuters.com@reuters.net)