Facebook co-creator Mark Zuckerberg pocketed more than a billion US dollars (£630 million) today after one of the biggest US stock market flotations.
The social networking site's shares rose 5% early in their first day of trading after the listing valued the company at 104 billion dollars (£66 billion) - bigger than Amazon or Disney.
The sale of 421 million shares at 38 US dollars (£24) each is thought to have netted up to 18.4 billion dollars (£11.6 billion) for the company.
And chief executive Mr Zuckerberg, who created the website in his Harvard University dorm room in 2004, sold about 30 million shares, pocketing some 1.15 billion US dollars (£724.6 million).
He will retain a large stake in the company, making him worth an estimated 19.1 billion US dollars - the 23rd richest person in the world at the age of 28.
One thousand millionaires are expected to be created by the flotation, including a small number of the 100 London-based staff.
Trading in the shares was delayed by about half an hour due to technical problems today.
Mr Zuckerberg's reported wealth was about the same as the £12.3 billion market value of Royal Bank of Scotland, after its shares fell 5% today.
Investors such as U2 frontman Bono are thought to have made huge sums, with music magazine NME predicting the float has made the singer the richest rock star on the planet.
James Hughes, chief market analyst at Alpari UK, said: "The share price jumped from 38 dollars per share to a high of 42 dollars in the first 15 minutes of trading.
"However, the real value of Facebook is not likely to be known until the hype of the IPO has died away and investors have been able to digest how the company is going to evolve to be the money making machine many expect it to be."
The status on Mr Zuckerberg's Facebook page read: "Mark listed FB on NASDAQ."
Despite the hype and the success of its early trading as a listed company, many believe the stock is overvalued.
A recent Bloomberg survey of 1,250 global investors, analysts and traders found that 79% said Facebook's valuation was not justified, with only 7% deeming the valuation fair.
Facebook's mobile phone platform is thought to need improvement, while its effectiveness as an advertising space has also been questioned.
These doubts were brought into sharp focus on Tuesday when General Motors, the US's largest car manufacturer, said it would stop advertising on the site.
Facebook has more than 900 million users who log in at least once a month, but it makes only a few dollars per year from each one, chiefly through advertising.
The site's revenue last year was 3.7 billion dollars (£2.34 billion), up from 153 million dollars (£96 million) in 2007, with the majority earned through advertising.
But social gaming on Facebook was a big money-spinner and there was also potential for further exploitation of data on users to enable more targeted advertising.
Ajay Bhalla, professor of global innovation management at Cass Business School, said: "With its IPO priced in excess of 100 billion dollars, Facebook has no doubt been extremely successful in capturing the investor mood at the right time.
"However, investors cannot bank on the current undisputed position it commands in the social network world.
"The ability of Facebook to reinvent itself will depend not just on having a sticky customer base but also on its capacity to introduce new products."
And the company's laid-back management style that sees Mr Zuckerberg wear his trademark hoodie and sandals may also have to change now the company is accountable to shareholders.
Richard Hunter, head of equities at Hargreaves Lansdown Stockbrokers, said worries had been expressed about corporate governance at the company - especially the power still resting with the founder.
Mr Zuckerberg is thought to control more than 50% of the shares in the company as part of agreements with other shareholders.
Trading began under the ticker symbol FB two days after massive interest in the sale prompted the company to boost the number of shares it planned to sell, with 84 million more - worth up to 3.2 billion dollars (£2 billion) - being added to the IPO.
But the entire increase comes from insiders and early investors, so the company will not benefit from the additional sales.
Facebook board members Peter Thiel and James Breyer are among those who sold more shares, but Mr Zuckerberg is not thought to have increased the number he sold.
Facebook is the latest in a series of online firms to sell shares to the public in recent months, following online voucher firm Groupon in November and online games maker Zynga in December.Reuse content