The founders, Garrett Camp and Geoff Smith, bought the company back with the help of investors including Ram Shriram of Sherpalo Ventures, Accel Partners, and August Capital, they said. Financial terms were not disclosed.

Camp will be chief executive of the company.

"We realized there were few long-term synergies between the two businesses," Camp said in a release. "It is best for us to part ways and focus on our respective strengths."

StumbleUpon, founded in 2001, has more than 7.4 million users and issues 425 million recommendations per month. The company suggests Web sites based on reader reviews and personal preferences of its members.

When eBay purchased the company two years ago, the startup was considered a pioneer of the so-called "Web 3.0" niche. The term refers to technology which pairs up general Internet search capability with a user's personal data and aggregated community data, in an effort to deliver more relevant results than a standard search engine such as Google Inc.

But San Jose, Calif.-based eBay itself has stumbled, acknowledging last month that it still has a long way to go in improving its online marketplace. Chief Executive John Donahoe, echoing investors, said at the time that the marketplace business has not kept up with the changing competitive landscape and customers' needs.

Ebay shares fell 39 cents, or 2.6 percent, to close at $14.63 on Monday. Shares gained 25 cents to $14.88 in after-hours electronic trade.

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