The Nasdaq composite index closed up 34.21 to 2,159.67, while the Dow Jones industrial average fell 63.81 to 10,502.40.
Nasdaq trading was halted for an hour when it suffered a second unplanned shutdown in as many days. The outage rippled through exchanges and trading desks across the nation: The Chicago futures and options exchanges also extended trading hours, and the main U.S. stock market gauges kept ticking beyond their normal 1 p.m. PDT close.
Random network outages caused problems that affected price quotes for stocks, a Nasdaq spokesman said. The market suspended trading on its SOES and SelectNet stock order routing systems from 11:31 p.m. PDT to 12:33 p.m. PDT.
"There are market makers who are not seeing their quotes, and so it's not anything like a normal environment," said Matthew Johnson, head of U.S. cash trading at Lehman Brothers. "It's organized chaos, but it's very chaotic."
Shares in Microsoft lost their steam after an initial celebration of Thursday's court ruling. The stock rose 26 cents to $73. Analysts said the ruling shouldn't affect the stock greatly. Expectations that the appeals court would reject the breakup order were already built into the stock price, they said, and there are a gaggle of legal possibilities for the company yet to be sorted out.
Commerce One warned that its second-quarter revenue will miss expectations. The software maker also announced some good news: Germany's SAP is giving it an injection of $225 million. Commerce One's stock rose $1.58 to $5.84.
Agere Systems said it will lay off an additional 4,000 employees, or about 25 percent of its work force, and expects to take up to $900 million in charges as it copes with a severe downturn in the semiconductor industry. Shares in the optical components maker rose $1.31 to $7.30.
Online grocer Webvan's shares were down a penny to 8 cents as the company's shareholders voted to implement a 25-to-1 reverse stock split--one of the few moves that can save the company from getting kicked off the Nasdaq.
Among technology bellwethers, Oracle fell 18 cents to $19; Cisco Systems fell 38 cents to $18.20; and Intel fell 39 cents to $29.25.
Amazon.com fell 21 cents to $14.15. AOL Time Warner rose 92 cents to $53. Yahoo was up 61 cents to $19.99.
Staff writers and Reuters contributed to this report.