Symantec ( SYMC) contributed to the Nasdaq 100's plunge Thursday, as losers outweighed winners in a tech sector heavy with earnings reports.

Symantec shares were sliding 12.8%, after the IT security company beat fiscal second-quarter expectations but offered weak guidance . Excluding items, Symantec posted earnings of $263 million, or 29 cents a share, compared with $261 million, or 26 cents a share, in the year-ago period. Analysts were expecting earnings of 26 cents a share.

For the third quarter, Symantec sees revenue of between $1.41 billion and $1.45 billion. Excluding charges, it sees earnings of between 25 cents and 30 cents a share. Analysts are expecting revenue of $1.47 billion and earnings of 31 cents a share. The stock was falling $2.69 to $18.33.

Cadence Design Systems ( CDNS) was falling 11.9% after the semiconductor design software maker also narrowly beat third-quarter expectations but provided lackluster guidance.

Excluding items, the company said it earned $97.4 million, or 33 cents a share, vs. analysts' expectation of 32 cents a share. For the fourth quarter, Cadence forecast revenue of $465 million to $475 million and earnings, excluding items, of 45 cents to 47 cents a share. Analysts were expecting revenue of $468.1 million and earnings of 46 cents a share. Shares were losing $2.57 to $19.12.

Symantec and Cadence are both components of the Nasdaq 100, which was sliding 27.25 points to 2161.34.

Palm ( PALM) shares also were sliding 18.2% after Bear Stearns lowered its rating on the handheld device maker to underperform from peer perform. RBC Capital Markets reiterated its sector perform rating, but dropped its price target to $7 from $16. The cuts come a day after Palm closed its $325 million investment from Elevation Partners. Shares were falling $1.85 to $8.33.

NII Holdings ( NIHD) was plummeting 19.8% after the Latin American digital wireless communications provider beat Wall Street's third-quarter outlook, but reported slowing subscriber growth. The company reported adjusted net income of $104 million, or 61 cents a share, on revenue of $853 million. Analysts were expecting earnings of 53 cents a share on revenue of $847 million.

NII reported 327,000 net subscriber additions, bringing its total digital subscriber base to 4.4 million, up from 3.2 million this time last year. That's a little bit slower than expected -- NII blamed hurricanes in Mexico -- and the company acknowledged it "has some ground to make up" to reach its guidance of 1.275 million net subscriber additions for the year. The company's churn rate also increased to 1.6% from 1.5% in the year-ago period. Shares were losing $13.75 to $55.69.

The down day did, however, produce some sizable winners. Akamai Technologies ( AKAM) was jumping 14.3% after the Internet infrastructure company beat profit expectations and upped its full-year outlook. The company reported adjusted net income of $62.4 million, or 34 cents a share, on revenue of $161.2 million. Analysts polled by Thomson Financial had expected earnings of 33 cents a share on revenue of $161 million.

For the full year, the company now expects revenue of between $625 million and $629 million, up from its earlier view of $615 million to $625 million, according to Reuters. Akamai also sees normalized earnings of $1.28 to $1.29 a share. Analysts had forecast earnings of $1.27 on revenue of $625.4 million. Shares were gaining $4.71 to $37.68.

Monster Worldwide ( MNST) was also rising 7.1%, after the online job search site swung to a third-quarter profit. The company earned $33.3 million, or 25 cents share, vs. a loss of $83.8, or 64 cents a share, in the year-ago period. Revenue also jumped 18% to $337 million. Shares were gaining $2.57 to $38.64.

Advent Software ( ADVS) was adding 18% after the company beat expectations for the third quarter and guided above expectations for the fourth. The investment management software maker reported earnings of 12 cents a share on revenue of $55.5 million, up 21% from a year ago. Reuters saw earnings of 7 cents a share. For the fourth quarter, Advent sees revenue of between $56 million and $59 million, guiding above Reuters' view of $56.9 million. Shares were climbing $8.36 to $54.90.