eBay is suing Craigslist to "safeguard its four-year financial investment". The auction site owns a 28.4% stake in the ad listings company.

In a statement, eBay has said that in January, Craigslist executives took actions that "unfairly diluted eBay's economic interest by more than 10%" although has not detailed the actions.

All that is revealed in the closed case documents is the claim that Craigslist's founder Craig Newmark and its CEO Jim Buckmaster adopted unspecified measures that have "disadvantaged" eBay and its investment.

Craigslist has said it was surprised and disappointed by eBay's "unfounded allegations" and that the lawsuit "came to us out of the blue".