Updated from 1:11 p.m. EDT

Shares of Autobytel were among the worst-performing technology stocks Monday, falling 29.6% after the Internet automotive marketing services company withdrew its 2004 earnings guidance and warned that 2005 earnings would fall below previous guidance.

The company did not specify what 2005 earnings would be, saying only that they would be "substantially lower than previous guidance." Autobytel said that higher operating costs, including higher acquisitions costs, costs related to Sarbanes-Oxley compliance and costs associated with a previously disclosed internal review of its financial statements led to the earnings revision. Autobytel said that earnings guidance of 25 cents a share during 2004 "should no longer be relied upon." The company left its sales guidance for 2004 and 2005 intact. Analysts polled by Thomson First Call had been expecting 2004 earnings of 24 cents a share on sales of $123.6 million and 2005 earnings of 41 cents a share on sales of $153.8 million. Shares traded down $2.30 to $5.46.

TippingPoint rose 11.9% after the company agreed to be acquired by 3Com for about $430 million in cash. The $47-a-share offer represents a 12.8% premium over Friday's closing price of $41.66. The deal is expected to close in February. TippingPoint, which provides network-based intrusion prevention systems, will operate as a division of 3Com once the deal closes. Shares traded up $4.94 to $46.60.

Shares of Sirius Satellite Radio ( SIRI - Get Report) climbed 5.9% after the company was added to the Nasdaq 100, effective Dec. 20. The index comprises the 100 largest nonfinancial Nasdaq stocks on the basis of market capitalization. Shares traded up 45 cents to $8.04.

PeopleSoft ( PSFT) rose 10.3% after the company finally agreed to be acquired by Oracle ( ORCL - Get Report) for $10.3 billion. The $26.50-a-share price tag represents a 10.4% bump over the $24-a-share offer that PeopleSoft had recently termed inadequate. "After careful consideration, we believe this revised offer provides good value for PeopleSoft shareholders and represents a substantial increase in value from October," PeopleSoft said. Shares of PeopleSoft traded up $2.47 to $26.42, while shares of Oracle traded up $1.35 to $14.63.

Shares of Conexant Systems ( CNXT) traded actively after the chipmaker warned that it now expects a first-quarter operating loss of 18 cents to 20 cents a share on sales of $140 million. Analysts had been expecting a loss of 6 cents a share on sales of $177 million. In November, Conexant forecast a first-quarter loss of 6 cents to 7 cents a share on sales of $175 million to $185 million. The revised guidance includes a one-time charge of $40 million to $50 million, which reflects lower market prices and reduced demand for its DSL and wireless LAN products. Shares ended the day unchanged at $1.87 on volume of more than 34 million shares, or almost four times its average daily volume.

Other technology volume leaders included Microsoft ( MSFT), up 17 cents to $27.25; Lucent , down 9 cents to $3.71; Intel ( INTC), up 7 cents to $22.63; Cisco ( CSCO), down 15 cents to $19.27; and Nextel Communications , up 23 cents to $29.99.