On the other side of the Atlantic, too, prices rocketed after the US government outlined its plan to rescue the ailing financial system.
The US Treasury Secretary said he intends to create a rescue fund, worth hundreds of billions of dollars, to cover the bad debts on US mortgages that are dragging down the financial system.
Henry Paulson said he will ask Congress to take action on legislation next week.
He also said he wants to update the financial regulatory system, but that would have to wait until the end of this "difficult period".
"I am convinced that this bold approach will cost American families far less than the alternative, a continuing series of financial institution failures, and frozen credit markets unable to fund economic expansion."
President Bush said: "This is a pivotal moment for America's economy.
"We must act now to protect our nation's financial health from risk."
He said government intervention was essential due to the precarious state of the financial markets.
US Treasury Secretary Henry Paulson has said the government needs to take additional steps to help boost the US financial market - but would have to get Congress' approval.
The US Treasury confirmed it will guarantee money market funds up to an amount of $50bn to ensure their solvency.
The country's financial regulator has also temporarily halted short-selling until October 2, following Britain's lead taken by the Financial Services Authority from midnight.
That came after the Prime Minister told Sky News that the behaviour of some City institutions had been 'irresponsible'.
US Treasure Secretary Henry Paulson has warned he was hatching a plan to rescue banks from the "toxic" assets that have led to the crisis.
New York's main share index responded by posting its biggest gain for nearly six years last night - up 410 points, or nearly 4%.
I think we need, at the very least, a return to good old, boring banking
Europe's central banks have offered up more cash to jittery banks, to boost confidence and persuade them to lend to each other.
The European Central Bank, which oversees the 15-nation euro zone, has offered $40bn. In London, the Bank of England said it provided nearly ÂŁ20bn.
The FSA measures are designed to stop traders creating a lack of confidence in companies by selling shares, actively contributing to a fall in price from which they profit when they buy them back.
Halifax Bank of Scotland blamed the practice for wiping more than ÂŁ3bn from its value before a takeover by Lloyds TSB reversed its fortunes.
SKY
Quite a rollercoaster