The M3 figures - which include broad range of bank accounts and are tracked by British and European monetarists for warning signals about the direction of the US economy a year or so in advance - began shrinking last summer. The pace has since quickened.
The stock of money fell from $14.2 trillion to $13.9 trillion in the three months to April, amounting to an annual rate of contraction of 9.6pc. The assets of insitutional money market funds fell at a 37pc rate, the sharpest drop ever.