World equity markets plunged again yesterday, ending a week-long dive that matched the falls during the Great Crash of 1929.

The turmoil prompted a pledge from global policymakers to implement an aggressive but broad-brush plan to combat the financial crisis. Policymakers from the Group of Seven nations meeting in Washington said they would use "all available tools" to prevent the failure of any systemically important bank after a day of almost indiscriminate selling in Asia and Europe, and unprecedented volatility in the US.