New York ? Unexpectedly strong profits at Cisco Systems delighted investors starved for good news Wednesday, sending the Dow Jones industrials up more than 300 points and the Nasdaq composite index up more than 120.

It was Wall Street’s biggest rally since the rebound that followed the post-Sept. 11 selloff. But analysts cautioned against reading too much into the advance, attributing it more to bargain hunting on recent selling, than any improvement in sentiment or business. They also noted that the market has developed a habit of rallying unsustainably.

Traders look at numbers as the final bell nears at the New York Stock Exchange in New York. The Dow Jones closed up 305.28 at 10,141.83 on Wednesday. The sharp rally was triggered by Cisco, after reporting higher-than-expected third-quarter profits late Tuesday.

“Investors have been waiting for a reason to buy. The catalyst today was Cisco,” said Jack Francis, managing director at UBS Warburg. “But this is just a snapback rally. Nothing fundamental has changed in corporate America and I don’t think this is a turnaround.”

The Dow closed up 305.28, or 3.1 percent, at 10,141.83. It was the biggest point and percentage gain since Sept. 24, when the average advanced 368.05 and 4.5 percent.

Broader stock indicators fared even better. The Nasdaq soared 122.47, or 7.8 percent, to 1,696.29, its eighth largest percentage gain ever and biggest point gain since April 18, 2001, when the index advanced 156.22.

The rally was triggered by Cisco, which climbed $3.19, or 24.4 percent, 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.

Cisco rival Juniper Networks rose $1.19, or 14.1 percent, to $9.62, while software company Microsoft jumped $5.50, or 11 percent, to $54.97, helped by a surge in European sales of its Xbox video game systems.