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The US central bank kicks off a two-day meeting later in the day and markets are on alert for any guidance on when and how quickly it will look to wind down its bond buying programme.
After a calmer day on Asian markets, European shares opened down 0.3%, giving back some of the previous day's gains.
"I don't think we will get any great retreat from the expectation that tapering (slowing of bond purchases) is really quite imminent," said Nick Beecroft senior market analyst at Saxo Bank.
"I think the Fed is secretly sitting with its fingers crossed, hoping that the froth continues to be skimmed off asset markets. I don't think they will be bothered at all if the S&P500 or other risk markets fall 5 or 10%, as long as it didn't happen in a (single) day."
The dollar hovered above a two-month low against the yen while
Comments from European Central Bank chief Mario Draghi that the bank remained ready to cut rates again if needed added some extra pressure to an already slightly lower euro.
In the debt markets, German Bund futures dipped in line with US Treasuries on the expectations the Fed may signal it is moving closer to trimming its bond purchases. Analysts also had one eye on the release of Germany's ZEW business sentiment survey at 0900 GMT.
