The Nasdaq composite index fell 81.47, or 2 percent, to 3,685.52, and the Standard & Poor's 500 index inched up 7.27 to 1,438.10.
The Dow Jones industrial average rose 84.97 to close at 10,606.95, led by Eastman Kodak, which rose $2.69 to $57.56.
At the end of regular trading, Intel closed down $2.13 at $64.63, and Microsoft dropped $1.13 to $68.69. Both are Dow components.
"The markets are focused more and more on valuation and stability," said Brian Belski, a market strategist at U.S. Bancorp Piper Jaffray. Belski said the market turbulence of the past few months has drained enthusiasm, compelling investors to buy more stable stocks.
"People have taken on a lot of pain this year, and they're being very selective," he said. "When people are thrown for a loop, they tend to buy more defensively."
Economic reports released today gave investors some reason for optimism. Manufacturing activity in July was unchanged from June, according to the National Association of Purchasing Managers' index, which remained at 51.8 percent. The data showed slowing growth in inventories and overall manufacturing but an acceleration in prices for material and labor.
Consumer spending increased 0.5 percent in June compared with May's 0.3 percent increase, according to Commerce Department data released today. However, when price increases are excluded, spending increased only 0.2 percent in June, compared with a 0.3 percent increase in May.
Construction spending also dropped for a third straight month, falling 1.7 percent in June following May's 0.2 percent decline.
Overall, some analysts said the data paints a picture of a slowing economy, which could keep the Federal Reserve from raising interest rates when it meets in late August.
The CNET tech index lost 34.97 to close at 2,697.91. Losers edged out winners, with 70 of the 97 stocks in the index falling, 24 rising and three remaining unchanged.
Nearly all of the 18 sectors tracked closed lower. Internet services companies posted the sharpest drops, falling 3 percent, while makers of semiconductors and semiconductor equipment followed close behind, dropping nearly 3 percent each. Distributors of computer components were the day's largest gainers, climbing a slim 0.86 percent.
The initial public offering of SpeechWorks International posted the highest percentage gain on the Nasdaq. Shares of the maker of speech recognition software rose $36.75, or nearly 184 percent, to $56.75 on a volume of 14.9 million shares.
Meanwhile, S1 shares took a hit after the company said revenue may not meet analysts' expectations in the second half of the year.
The online financial services company reported a second-quarter loss of $2.82 a share, wider than the $2.74 estimate of analysts surveyed by First Call/Thomson Financial. The shares fell $7.31, or nearly 29 percent, to $18.13. Volume exceeded 7.4 million shares, nearly five times the stock's average daily volume of 1.5 million shares.
Among members of the CNET tech index, Inktomi fell $8.69 to $98.31, and RealNetworks dropped $3.63 to $38.81.
Shares of EarthLink Network fell $1.56, or nearly 13 percent, to $10.94, while Tollgrade Communications fell $21.66, or almost 22 percent, to $83.31 on a volume of 2.9 million shares, nearly five times more than the phone equipment maker's average volume of about 600,000 shares.
The Philadelphia semiconductor index fell 38.02, or almost 4 percent, to 955.83, led by chipmaker Lattice Semiconductor, which fell $4 to $50.88.