"CBS Corp. says it has agreed to buy online technology news and entertainment company CNet Networks Inc. for about $1.75 billion.

The owner of the CBS television network and TV stations said Thursday the deal will boost its online presence and allow it to tap the growing market for online advertising.

The New York media company says it has offered $11.50 per share for San Francisco-based CNet. The bid represents a 45% premium above CNet's closing price of $7.95 on Wednesday.

One of CNet's largest shareholder has been agitating for a shake-up at the company after its shares fell sharply in the past year. CNet's Web sites include News.com, TV.com, Mp3.com, MySimon and GameSpot.

CNET shares soared more than 41%, or $3.30, to $11.25 in premarket trading."