Stocks plunged Thursday after falling home sales and rising jobless claims provided the latest evidence that credit market troubles are taking a toll on the real economy.

Weak results from automakers also fueled the market's worst sell-off in a month, and good news from a number of technology stocks did little to help that sector. Worries about the health of Washington Mutual (NYSE: WM) also weighed on the market.

The result was a loss of more than 2% for the major indexes, the worst day for the Dow and S&P since June 26.

Some technology investors had reason to smile, though.

Qualcomm (NASDAQ: QCOM) rocketed 17% after settling its long-running legal battle with Nokia (NYSE: NOK), and Amazon.com (NASDAQ: AMZN) surged 11.6% on blow-out results.

Baidu.com (NASDAQ: BIDU), Sybase (NYSE: SY), Cirrus (NASDAQ: CRUS), GSI Commerce (NASDAQ: GSIC), Ariba (NASDAQ: ARBA), Vasco Data (NASDAQ: VDSI), Digi (NASDAQ: DIGI) and Teledyne (NYSE: TDY) were other earnings winners.

Microsoft (NASDAQ: MSFT) and Apple (NASDAQ: AAPL) both lost 4% after Microsoft's analyst meeting included tough talk about growing competition from Apple's Mac sales.

Cadence Design (NASDAQ: CDNS), TechTarget (NASDAQ: TTGT), MEMC (NYSE: WFR), Teradyne (NYSE: TER) and Benchmark Electronics (NYSE: BHE) fell on their earnings news.

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Juniper (NASDAQ: JNPR) lost 1.4% despite getting its new CEO from Microsoft. After the close, its shares jumped 10% after the company's results beat Wall Street estimates.

The Nasdaq tumbled 45 to 2280, the S&P lost 29 to 1252, and the Dow plunged 283 to 11,349. Volume declined to 5.95 billion shares on the NYSE, and 2.55 billion on the Nasdaq. Decliners led by a 27-6 margin on the NYSE, and 20-8 on the Nasdaq. Downside volume was 88% on the NYSE, and 81% on the Nasdaq. New highs-new lows were 33-134 on the NYSE, and 53-105 on the Nasdaq.