Mark Zuckerberg-led Facebook put up 421 million shares of its common stock up for sale late yesterday at a price to the public of USD 38 per share, the company said in a statement.

The shares would begin trading on the NASDAQ exchange today under the symbol 'FB'. In addition, Facebook and the selling stockholders have granted the underwriters a 30-day option to purchase up to 63,185,042 additional shares of Class A common stock to cover over-allotments, if any, it added.

The over-allotment could see Facebook raising a total of USD 18.4 billion. Zuckerberg is expected to ring the opening bell at Nasdaq remotely from Facebook's California headquarters.

Welcoming the IPO, the company is holding an overnight "hackathon" where engineers stay up all night writing programming code to come up with new features for the site.

The public offer is expected to close on May 22. Facebook roped in financial giants like Morgan Stanley, J P Morgan, Goldman Sachs, Bank of America Merrill Lynch, Citigroup and Deutsche Bank Securities to serve as book runners for the offering.

At USD 16 billion, the size of Facebook's IPO is the third-largest for a US company, with the largest being the Visa IPO, which raised USD 17.9 billion in 2008, according to Renaissance Capital. For a company that began in a Harvard dorm eight years ago, the IPO will bring a windfall which will give it the financial muscle to develop more services and features and employ the best in the business.

Zuckerberg is selling about 30 million of his shares, but Zuckerberg is selling about 30 million of his shares, but will still remain Facebook's largest shareholder.

He will own 503.6 million shares, or 32 per cent of Facebook's total shares after the IPO, with his stake in the company worth USD 19.1 billion, going by the 38 dollars stock price. He will control the company with 56 per cent of its voting stock. Zuckerberg, who celebrated his 28th birthday on Monday, has created a place for himself in the pantheon of Silicon Valley wizards who changed the way people use technology.

Apple CEO Steve Jobs was among Zuckerberg's mentors. In Facebook's meteoric rise since it was founded in 2004, Zuckerberg's public persona took a hit as his friends from Harvard claimed he stole their idea of a social network that let people share everything from their photos to their thoughts online. Facebook was the subject of a Hollywood movie that went on to win three Academy Awards last year.

At a market value of USD 104 billion, Facebook would be among the most valuable US firms, ahead of giants like Amazon which is valued at USD 98 billion and Cisco USD 89 billion. It would however still be behind Google (USD 203 billion) and Apple (USD 495 billion).

The Facebook IPO will also make several of its employees millionaires if not billionaires. California estimates that it could get USD 2 billion from the taxes that Facebook's newly minted millionaires will owe to the state.

Facebook's IPO had been closely followed in the media as well as by corporate America.

The company conducted roadshows in major cities like New York, Chicago and Boston, with Zuckerberg's hoodie and casual dressing styling also grabbing headlines.

PTI