** Shares of British homebuilder Vistry VTYV.L down more than 10% at 292.8 pence, top loser on FTSE midcap .FTMC index, which is up 0.5%
** Shares hit lowest since August 2011
** VTYV expects H1 profit to be significantly lower than year ago
** Co pauses share buyback programme to focus on reducing debt and ramps up discounts to clear inventory
** Expects events in the Middle East to create upward pressure on material and labour prices into H2
** Including session's moves, stock down about 52%
(Reporting by Megha Anilkumar Nair)
((MeghaAnilkumar.Nair@thomsonreuters.com;))