One forty, one forty-four, one forty-seven, one thirty-nine. This was just four days. The speed at which the euro rose against the dollar and sterling last week, before its reversal against the dollar on Friday, has been astonishing. In trade-weighted terms the euro touched its highest level ever.

This convulsion in foreign exchange rates is the direct response to unsynchronised monetary policies. The Federal Reserve announced last week that it would switch to aggressive monetary easing, a policy to increase the liquidity in the economy by purchasing financial assets outright.