Until Thursday the dollar was doing fairly well. The US economic data were not the punchiest ever seen: manufacturing activity, as measured by the Institute of Supply Management's purchasing managers' index, touched a six-year low. But a string of Federal Reserve bosses continued to hint that dollar interest rates would begin to head higher this month and that was all investors seemed to care about.

The dollar's bull run came to a dramatic end on Thursday when the European Central Bank revealed its latest measures to lift euro zone inflation from 0.1% to its 2% target. To say the least, they came as an anticlimax and the euro shot higher. Typically, as investors bought the euro they sold the dollar. So the dollar ended up with a loss of three and a quarter cents to the euro - 3% - and it was down by a quarter of a cent against sterling.