Ben Bernanke, head of the US Federal Reserve, said on Tuesday that the weak dollar had “contributed to the unwelcome rise in import prices and consumer price inflation”. He added that the Fed was watching “the implications of changes in the value of the dollar for inflation and inflation expectations”.

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John Authers on Ben Bernanke’s remarks on the US dollar

Such comments might seem unexceptional to the uninitiated. But they triggered a rise of 2 cents in the dollar’s value against the euro in a matter of minutes and dramatic rises against other currencies.