Big US retailers including Walmart contributed to the uncertainty by disappointing investors with their trading updates yesterday.
The FTSE 100 Index along with other world markets has endured a rocky ride since the US presidential election and was flat at 5677.4 today, having closed more than 40 points lower last night.
Ongoing fears that President Obama will be unable to strike an agreement to avoid America's fiscal cliff on January 1 have damaged confidence.
There was little in the way of heavyweight corporate news, although Panmure Gordon stockbrokers upgraded outsourcing firm Serco in the wake of a trading update confirming that it has been trading in line with expectations. Shares in the FTSE 100 Index company were 15p higher at 559.5p.
It was followed on the risers board by engineering group IMI after it said underlying revenues for the four months to the end of October were 3% ahead of last year. IMI's shares responded with a rise of more than 2%, up 22.25p to 964.25p.