The £330m acquisition is the first since News Corporation had an emergency meeting in February with 50 executives to discuss its internet strategy.
Nate Elliott, an analyst at Jupiter Research, said: "It's a bit surprising as [Intermix] has only just removed the cloud of legal action by the New York State Attorney over allegedly putting spyware onto users' machines.
"It's a low-level portal with a wide mix of services. But it's getting good traffic so it is doing well at attracting eyeballs with things like movie trailers and celebrity content. The tie-in with Fox [owned by News Corporation] will clearly help it do more of that."
Murdoch described Intermix as owning "some of the web's hottest properties". It has 30 sites of which the jewel is myspace.com which includes blogs, chat, music, picture sharing services and classified advertising.
Myspace.com is predicted to double News Corporation's US web traffic to 45 million unique users monthly.
Analysts have suggested that the acquisition is driven by News Corporation's wish to increase its share of global internet advertising revenues, which are expected to grow 30 per cent this year.
During the internet boom years News Corporation spent £200m on the now defunct eVentures and £460m on healthcare site Healtheon. It also launched the highly successful Sun web site to support its UK tabloid newspaper.
Intermix will become part of Fox Interactive Media, the new home of News Corporation's internet assets.
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