Tech moguls lose big on Forbes 400 The person who experienced the biggest losses, however, was Facebook executive Mark Zuckerberg. Zuckerberg's personal wealth reportedly dropped $8.1 billion after the social network went public in May. Zuckerberg still has a personal wealth of $9.4 billion, according to the list, which puts him in the 36th slot on the list of the nation's richest people. Facebook, Zynga and Groupon were all hailed as promising initial public offerings that would show how hot the tech industry could be - and also set off alarms about a new tech bubble. All three are now trading far below their opening prices. Facebook, as of Wednesday, was trading at just under $23 per share from its debut price of $38. Zynga was trading at around $3.17 per share from its IPO price of $9.50 Groupon, priced at $20 for its market debut, was trading at $5.15 per share - a price that's up nearly 10 percent on the day because of the company's announcement Wednesday morning that it would begin processing credit card payments. The list brings into focus a longer narrative that's been dominating the technology industry this year: new technology companies with business models based on more intangible ideas - from Groupon's coupons to Zynga's in-game goods. It's also worth noting that Zynga and Facebook's destinies are closely linked. After all, it's not solely bad news for tech. There are at least two notable figures who are doing very well, according to the list. Larry Ellison, of Oracle, is third on list with a fortune of $41 billion, even as his company grapples with the challenge of providing more robust cloud services. The other techie doing well on the list, of course, is Forbes 400 regular Bill Gates - the richest person on the list for the 19th year thanks to a $66 billion net worth. Others rounding out the top 10 are investor Warren Buffett, Charles and David Koch of Koch Industries, four members of Wal-Mart's Walton family and businessman and New York Mayor Michael Bloomberg. (Washington Post Co. Chairman and chief executive Donald E. Graham is a member of Facebook's board of directors.) Facebook's Zuckerberg drops off top billionaires list AP: Groupon launches payments service in U.S. to let merchants take credit cards, rivals Square Zynga posts loss; Facebook investors worry