In New York, unexpectedly strong profits at Cisco Systems delighted investors starved for good news on Wednesday, sending the Dow Jones industrials up more than 300 points and the Nasdaq composite index higher by more than 120.
It was Wall Street's biggest rally in about eight months.
But analysts cautioned against reading too much into the advance, attributing it more to a rebound from recent selling, than any improvement in sentiment or business.
They also noted that the market has developed a habit of rallying unsustainably.
The Dow closed up 305.28 points, or 3.1%, at 10,141.83, according to preliminary calculations.
It was the biggest point and percentage gain since September 24, when the average advanced 368.05 points and 4.5%.
Broader stock indicators fared even better. The Nasdaq rose 122.45 points, or 7.8%, to 1,696.27, its biggest point gain since April 18, 2001, when the index advanced 156.22 points. It was the eighth largest percentage gain ever.
The S & P 500 index was up 39.35 points, or 3.8%, at 1,088.84, its biggest point increase since April 18, 2001 and biggest percentage gain since September 24.
The sharp rally was triggered by Cisco, which climbed 24.3%, to $16.27 after reporting higher-than-expected third-quarter profits late Tuesday.
The network equipment maker and technology industry bellwether stopped short of predicting a recovery, though - saying instead that it expected little growth in the coming quarter. Still, that didn't curb Wall Street's buying.
Financial stocks were also strong on reports that Merrill Lynch and the New York attorney general were working on a settlement in the investigation of alleged conflicts of interest at the nation's largest brokerage firm.
