Central bankers would like to be able to get back to business as usual.

Stocks in Europe and the US slid as China unexpectedly increased its benchmark interest rate and after Apple's earnings forecast fell short of some expectations.

Shares on Wall St advanced overnight, helped by better-than-expected results from Citigroup and expectations the Federal Reserve would further ease monetary policy.

Waiting for that magic moment when one Australian dollar can buy one US dollar has assumed a symbolic importance.