Six days after the launch, three Harvard seniors claimed Zuckerberg reneged on an agreement to build a site for them and used their ideas to create what eventually became Facebook.
Cameron and Tyler Winklevoss and Divya Narendra claimed Zuckerberg had agreed to build a website called HarvardConnection.com for them before abandoning them to create his own site. They eventually filed a lawsuit that was settled in 2008.
As part of that settlement, they received 1.2 million Facebook shares. Those shares were worth $300 million when Facebook had its IPO.