European stocks finished sharply lower after a day of volatile trading.The indexes fell early on in the session as investors took profits, fretted about the strength of the economic recovery and worried the markets may be overvalued. Then they picked up on the release of encouraging economic data from the US as the Institute for Supply Management reported the manufacturing sector there grew in August for the time in more than a year and a half. In addition pending sales of previously owned homes in the US raced to a two year high in July. But the effect did not last. European banks were big losers, though Germany’s Commerzbank rose on a report it could return to profit next year. Oil prices were also on a rollercoaster ride.