FTSE falls for third day, U.S. stimulus concerns weigh

* FTSE 100 down 0.5 percent

* Sports Direct (Dusseldorf: ZVX.DU - news) drops after results

* Wood Group (Frankfurt: JWG1.F - news) falls; engineering profit to drop in 2014

By Tricia Wright

LONDON, Dec 12 (Reuters) - Britain's top share index fell for a third straight day on Thursday as uncertainty over the outlook for U.S. monetary policy continued to take its toll on investor sentiment.

Sports Direct was the sharpest faller on the FTSE 100, off 3.7 percent, with some analysts blaming the sporting goods retailer's comments on trading after it reported a rise in first-half profit.

"Solid (KOSDAQ: 050890.KQ - news) delivery from Sports Direct, but the rhetoric on current trading is not as bullish as usual and we are shaving forecasts (admittedly from the top of the range)," Oriel Securities said.

"The shares' momentum is unlikely to persist given the in-line nature of the results," said the broker, which has a "hold" rating on the stock. Sports Direct, up 92 percent in 2013, hit a record high on Wednesday.

Mid-cap energy services company Wood Group also came under pressure, off 10.7 percent, after warning that profits from its engineering division would be down by 10 to 15 percent next year due to continuing weakness in Canada.

Hopes for the traditional festive rally were further eroded on Thursday, with the FTSE 100 off 31.73 points, or 0.5 percent, at 6,475.99 points by 0855 GMT, taking its loss in December so far to 2.6 percent. The index has risen in all but two of the last 20 Decembers, Thomson Reuters Datastream shows.

Equities are suffering on worries over when the U.S. Federal Reserve will scale back its stimulus, with a provisional budget deal clinched in Washington on Tuesday fuelling concerns it may start the process as early as next week.

"(The market) thinks they're going to taper next week; the mood seems to have changed on that quite dramatically which I think might knock (a Santa rally) on the head," said Ian Williams, equity strategist at Peel Hunt.

As long as the FTSE stays above last week's low at 6,480 on a closing basis, the technical picture for the index remains intact, according to Fawad Razaqzada, technical analyst at Gain Capital (Other OTC: CGHC - news) . The index is however currently trading around this level.