What is off order book trading and how it is different from order book trading. When I check the 0r1O (LSE), Few websites show $1585.46 ( last order book trade which took place on 22nd of May) and few (e.g. yahoo ) return last price as $1802 which is an off book trade.
One more interesting fact I noticed is that Yahoo is returning last close as $1585.46 only which is the last order book trade ( took place on 22nd May ) though there have been continuous off book trades since then.
Edit: I wonder why few investors prefer off book trading over order book in such above cases. Since the last order book trade ( on 22nd of May ) this security has seen rise of $300 in it's price. Isn't it risky especially with this low amount of trading volume?