The tech index gained 6.38 points to 1,652.72. CNET's technology indexes were mixed.
But another series of anthrax detections--including one at CBS-TV News in New York and one involving a letter sent from Atlanta to Nairobi, Kenya--put a damper on the broader markets. The Dow Jones industrial average lost 69.75 to 9,163.22.
Quarterly reports from the likes of Advanced Micro Devices, Broadcom, Apple Computer and Macromedia helped boost the Nasdaq into positive territory.
In the semiconductor sector, Texas Instruments, Advanced Micro Devices and Broadcom reported quarterly results.
TI--down $2.89, or 10 percent, to $27.02--said it lost 3 cents per share on a pro forma basis, or 7 cents including all special items in its third quarter. Management said it can't predict when the company will return to profitability.
Advanced Micro Devices, or AMD, fell 21 cents to $9.50 after it posted its first loss in almost three years, blaming slow PC sales and a price war with rival Intel, which was off 22 cents to $24.35.
Broadcom, up $1.87, or 7 percent, to $29.94, was one of the few chipmakers to top estimates. The company, which specializes in chips for cable modems, said its third-quarter loss, excluding certain items, was 13 cents a share. First Call had expected the company to lose 15 cents a share on that basis.
In the software sector, Siebel Systems, SAP and Macromedia all reported results.
Siebel, which makes software for tracking sales and managing customer accounts, on Wednesday reported third-quarter profit of 7 cents a share, missing the 9 cents a share First Call had predicted. Shares lost 27 cents to $17.11.
German software maker SAP also disappointed investors; the company on Thursday reported worse-than-expected third-quarter results and slashed its full-year sales outlook. The company had been one of the few technology heavyweights to avoid a profit warning so far this year. Shares lost 73 cents to $25.83.
Macromedia's shares were up $1.19, or 8 percent, to $15.21 after the maker of Internet-design software on Wednesday posted a lost 6 cents a share, topping First Call's estimate for a loss of 15 cents a share.
Companies specializing in security software reported some better results.
Symantec--up $4.81, or 10 percent, to $52.58--reported a profit of 56 cents a share in the second quarter, ended Sept. 28, excluding certain items. First Call had expected Symantec to earn 43 cents a share.
Check Point Software Technologies, an Israeli Internet-security company, on Thursday said its third-quarter profits rose more than 20 percent, despite a shortfall in revenues after the Sept. 11 attacks. Shares rose $2.81, or 10 percent, to $31.93.
Other big-name tech companies reporting results included Apple Computer, up $1.01 to $18. The Mac maker said its profit in the fourth quarter was 18 cents a share, excluding one-time gains. Results Wednesday topped First Call's expectation for earnings of 16 cents a share.
Sprint announced layoffs along with disappointing results. The long-distance telephone company will eliminate 6,000 jobs, or 7 percent of its work force, and reported a third-quarter loss of $134 million, compared with a loss of $6 million a year ago. Shares fell $1.94, or 9 percent, to $20.05.
Companies scheduled to report quarterly results after Thursday's closing bell were on the rise. Microsoft rose 77 cents to $56.80; eBay was up $1.97, or 3 percent, to $59.06; and Sun Microsystems rose 8 cents to $8.88.
Among other actively traded shares, Oracle rose 60 cents, or 4 percent, to $14.26, and Cisco rose $1.12, or 12 percent, to $16.72.
AOL Time Warner fell 91 cents to $29.90, Yahoo fell 9 cents to $11.27, and Amazon.com fell 45 cents, or 5 percent, to $8.47.
Staff and Reuters contributed to this report.