CHICAGO (CNN/Money) - Technology stocks finished lower in a volatile, shortened session Thursday as disappointing unemployment numbers helped spark profit taking.

The Nasdaq Composite Index dropped 15.27 to close at 1,663.46, according to preliminary results. The Amex Technology Index shed 9.21 to 598.17, while the Morgan Stanley Technology Index finished 3.78 lower at 376.89.

Among blue chips, Microsoft (MSFT: Research, Estimates) fell 41 cents to $26.47, Intel (INTC: Research, Estimates) slipped 50 cents to $21.71, and IBM (IBM: Research, Estimates) lost 79 cents to $83.95.

Today's abbreviated session was volatile as investors digested a pair of economic reports. Shares headed lower after the Labor Department reported a higher-than-expected unemployment rate in June, while the new weekly jobless claims were also higher than anticipated.

Stocks began recouping some lost ground after the Institute for Supply Management reported the services sector grew at a faster-than-expected clip in June. After Wednesday's strong advance, however, investors opted to cash in on the rally. And with the earnings-reporting season set to begin, investors are becoming more selective with their positions.

To that end, a few earnings pre-announcements are beginning to trickle out. Siebel Systems (SEBL: Research, Estimates) gained 34 cents to $9.80 after the software maker said it plans additional cost-cutting measures and to restructure its operations. The company also said its second-quarter earnings would come in at the low end of its previous guidance and that customers are delaying purchases.

In other earnings-related news, webMethods (WEBM: Research, Estimates) tumbled 27 cents to $8.10 after the business software firm warned its first-quarter results would be below estimates, citing weak IT spending in the North American market.

Elsewhere, AT&T (T: Research, Estimates) shed 46 cents to $19.42 after Standard & Poor's lowered the telecom firm's long-term debt rating to "BBB" from "BBB+" late Wednesday. The agency cited a challenging market facing AT&T amid competitive pricing and the slow economic recovery.