San Francisco, Sep 16 (DPA) Adobe Systems is to buy internet services firm Omniture for $1.8 billion, the company said Tuesday. The deal will mark the biggest acquisition by Adobe since its $4.3-billion purchase of Macromedia in 2005.

Omniture, based in Utah, makes software that allows firms to analyze the use of their internet sites and help them maximize advertising and retail opportunities. Adobe, whose key products include Photoshop and Flash, will pay $21.50 a share for

Omniture, a 45-percent premium on the company's closing price prior

to the acquisition.

Adobe said that its net income in the third quarter fell 29 percent to $136 million, as revenue slipped to $697.5 million from $887.3 million a year ago. The results beat Wall Street expectations, and Adobe chief executive Shantanu Narayen said he was pleased with the 'solid revenue' for the quarter.