Updated from 1:31 p.m. EDT

Tech stocks were on the rise Thursday, boosted by

Checkfree's

( CKFR) steep ascent following a $4.4 billion buyout.

The e-commerce infrastructure provider's shares were gaining 23.3%, after the company announced it had accepted

Fiserv's

(FISV) - Get Fiserv, Inc. Report

all-cash offer of $48 a share. The offer represents a premium of more than 30% over Checkfree's closing price of $36.83 on Wednesday. The deal is expected to close by the end of the year. Checkfree shares closed up $8.57 to $45.40.

The Nasdaq 100, of which Checkfree is a component, was up about 21.5 points to 1966.60.

Sirenza Microdevices

( SMDI) was soaring 17.3%, after the company, which makes radio frequency components for wireless networks used in the defense and aerospace industries, easily beat Wall Street's second-quarter projections. Excluding items, the company earned $8.7 million, or 17 cents per share, compared to $7.2 million, or 16 cents per share, in the year ago period. A poll of analysts by Thomson Financial predicted profits of 14 cents per share. Sirenza's stock jumped $1.92 to $13.04.

O2Micro International

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jumped 7.6%, after swinging to a second-quarter profit and being upgraded by Needham & Co. The firm rated the stock a strong buy, up from buy, after O2Micro reported profits of $5.7 million, or 15 cents a share, compared to a loss of $2.5 million, or 6 cents a share, in the year-ago period. Shares gained 98 cents to $13.86.

Smith Micro Software

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advanced 15.6%, after the software maker was upgraded to market outperform from market perform by Rodman & Renshaw. The firm's rating change came a day after the company's adjusted earnings beat expectations. Shares gained $2.14 to $15.88.

8X8

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jumped 14.3%, after the voice over Internet protocol provider swung to a fiscal first-quarter profit. The company posted GAAP net income of $508,000, or a penny a share, compared to a net loss of $1.8 million, or 3 cents a share for the year-ago period. Analysts expected a loss of 3 cents a share. Shares gained 19 cents to $1.52.

On the down side,

Entegris

(ENTG) - Get Entegris, Inc. Report

sunk 12.6%, after the semiconductor component maker posted sliding second-quarter profits and guided lower than Wall Street's third-quarter expectations. The company reported net income of $14.8 million, or 11 cents per share, down from $18.2 million, or 13 cents per share, in the year-ago period.

Entegris expects sales from continuing operations to be down between 4% and 8%, to approximately $142 million to $148 million and earnings of between 5 cents and 7 cents a share, excluding certain expenses. Analysts polled by Thomson Financial expect earnings of 15 cents a share on revenue of $168.8 million. Shares fell $1.38 to $9.60.