The Nasdaq dropped 10.51 points to 2,138.21, and the Dow Jones industrial average fell 22.41 points to 10,571.31. The markets closed at 10 a.m. PDT for the holiday.
The steepest drop came from Internet Security Systems, which tumbled $20.18 to $29.99, but a flock of other security stocks also slipped. Network Associates was down 81 cents to $12.15, and VeriSign fell $2.05 to $58.45.
Another maker of Internet security software, Check Point Software, added to the sector's woes. The company warned that its revenue will miss estimates in the second quarter and could be off for the full year. Shares were down $6.36 to $44.59.
i2 Technologies was one of many software companies to say it will miss revenue targets and post a wider-than-expected second-quarter loss. The business-to-business software maker blamed the economic climate. Shares were up 37 cents to $18.60.
Web site software maker BroadVision, down 89 cents to $4.04, announced it will miss second-quarter expectations by a wide margin. It also announced the resignation of its chief financial officer.
Rational Software plunged $5.25 to $22.20 after a warning Monday night. The software development tools maker said first-quarter results may fall short of forecasts because of new signs of weakness overseas.
Software maker Epiphany, down $1.12 to $9.39, joined the warnings club when management said its second-quarter loss would be bigger than expected because of a slowdown in overseas sales.
Among technology bellwethers, Microsoft fell 15 cents to $70.45; Oracle rose 19 cents to $19.77; Cisco Systems fell 3 cents to $19.19, and Intel rose 43 cents to $30.49.
Amazon.com fell 40 cents to $14.13. AOL Time Warner dropped 30 cents to $ 52.76, and Yahoo shed 23 cents to $19.81.
Staff and Reuters contributed to this report.