A last-minute U.S. budget deal sent European shares to 20-month highs on Wednesday, pushing some regional indexes into "overbought" territory and leaving them vulnerable to a pullback.
The agreement to postpone steep austerity measures in the world's largest economy triggered a rally in assets that depend on economic activity, such as equities, but the deal was only a partial fix to the country's budget woes.
Meanwhile, the U.K.'s FTSE 100 topped the psychologically important 6,000 level, closing up 2.1 percent. The index last topped 6,000 in July 2011.
However, further U.S. political showdowns are expected over the next two months, all of which could dent investor sentiment and result in increased share price volatility.
"We'll see a few more days of euphoria but then the reality will set in," said Mike Turner, head of global strategy and asset allocation at Aberdeen Asset Management, adding he would sell futures contracts on major indexes at the first sign of fresh political jitters.
The euro zone Euro STOXX 50 and Germany's Dax moved into "overbought" territory on their 20-day Relative Strength Index, a momentum indicator, meaning that some short-term sellers may start to take profit on the indexes in the coming days.
In Europe, euro zone manufacturing output for December was released on Wednesday morning. The purchasing managers' index (PMI) data give an indication of the region's economic health in terms of industrial activity. The figure for the euro zone edged down to 46.1 in December from November's 46.2.