Shares of

SigmaTel

( SGTL) were among technology's losers Thursday, slumping 13% after the chipmaker slashed its first-quarter guidance.

The company now sees sales of $30 million to $35 million, down from an earlier view of $52 million to $60 million. Analysts polled by Thomson First Call had an average forecast for sales of $54.5 million. SigmaTel said its results were hurt by order pushouts, a decline in flash prices and slower-than-expected adoption of its STFM 1000 product, which was plagued by firmware issues and delays in reference designs.

The company also said a tax issue could lower earnings by as much as 50 cents a share. "The company is evaluating alternatives relative to this tax strategy and is not providing specific revised EPS guidance at this time," it said. In late January the company predicted that it would post a loss of 1 cent to 8 cents a share, excluding items, for the first quarter. Shares were trading down $1.36 to $8.77.

Nokia

(NOK) - Get Report

rose 4% after the cell phone maker lifted its forecast for 2006 mobile device market volume. The company now expects handset volume to rise 15%, up from an earlier view of 10%. Nokia attributed the better-than-expected outlook to strong subscriber growth. Shares were up 97 cents to $21.19.

Shares of

ATI Technologies

( ATYT) rose 8% after the graphics-chips maker's second-quarter results topped forecasts. The company earned $34.1 million, or 13 cents a share, on revenue of $672.4 million. Excluding items, the company earned $44.8 million, or 17 cents a share, for the February quarter. Analysts expected earnings of 11 cents a share, before items, and revenue of $648.4 million. During the year-earlier period, ATI earned $57.2 million, or 22 cents a share, on revenue of $608.2 million. Excluding items, the company earned $65.4 million, or 25 cents a share, in the year-ago period.

For the fiscal third quarter, ATI anticipates revenue of $640 million to $680 million. Analysts project sales of $643.8 million. Shares were higher by $1.27 to $17.

Google

(GOOG) - Get Report

fell 2% after the Internet search giant said that it would sell 5.3 million shares of stock. "This offering will partially meet the anticipated needs of index funds to purchase Google Class A common stock when Google is added to the

S&P 500

index," the company said. Google said the proceeds from the offering would be used for general purposes, including working capital and capital expenditures. Based on Wednesday's closing price of $394.98, Google would raise more than $2 billion in the offering. Shares were recently down $9.85 to $385.13.

Shares of

Tvia

(TVIA)

slid 9% after the provider of display processors said that fourth-quarter sales would be flat on a sequential basis. For the third quarter, the company posted sales of $2.7 million. The lone analyst forecast calls for fourth-quarter sales of $2.9 million. Tvia blamed the weak forecast on an unexpected material shortage. Shares recently were down 28 cents to $2.73.

Other technology movers included

Level 3 Communications

(LVLT)

, down 20 cents to $5.40;

Lucent Technologies

( LU), up 4 cents to $3.08;

Intel

(INTC) - Get Report

, down 12 cents to $19.70;

Sun Microsystems

(SUNW) - Get Report

, down 6 cents to $5.19;

Apple Computer

(AAPL) - Get Report

, up 21 cents to $62.54;

Oracle

(ORCL) - Get Report

, up 5 cents to $13.77;

JDSU

(JDSU)

, down 1 cent to $4.17;

Sirius Satellite Radio

(SIRI) - Get Report

, up 5 cents to $5.04;

Cisco Systems

(CSCO) - Get Report

, up 27 cents to $21.84; and

Microsoft

(MSFT) - Get Report

, up 17 cents to $27.19.