AN AMERICAN COURT has dismissed an appeal by two brothers who were seeking to back out of an earlier agreement about their stake in the social networking site Facebook, telling them they cannot renegotiate the settlement.

Twin brothers Cameron and Tyler Winklevoss had reached a settlement with the site’s chief executive and main mastermind Mark Zuckerberg in 2008, claiming that Zuckerberg had not given them a true indication of Facebook’s true value.

The brothers had accepted a $65m settlement at the time, which included $45m worth of Facebook stock – but claimed that the deal was based on a valuation of around $36 a share, while Facebook employees were themselves being offered shares at just under $9 each. When they were last traded last month, shares in the company – which has not been publicly floated – were worth $33 each.

A judge yesterday said the original settlement could not be undone, however, commenting that “at some point, litigation must come to an end.

“That point has now been reached,” judge Alex Kozinski wrote, finding that the Winklevosses were “not the parties bested by a competitor who then seek to gain through litigation what they were unable to achieve in the marketplace”.

PA reports that the third classmate involved in the original settlement, Divya Narendra, had not sought to renegotiate the deal.

Facebook has welcomed the ruling, which could yet be appealed to the US Supreme Court. The twins’ lawyers, however, have said they already plan to seek another rehearing before the end of the month.

The original settlement between Zuckerberg, Narendra and the Winklevosses formed the basis for David Fincher’s 2010 Oscar-winning movie The Social Network – in which the brothers were famously dubbed “the Winklevii” by the Zuckerberg character.

Zuckerberg’s legal concerns are not yet at an end, however; a New York man named Paul Ceglia has refiled a previous lawsuit in which he claimed to actually own an 84 per cent stake in the company, based on an agreement struck with Zuckerberg in 2003.