Facebook is set to close the books on its IPO, initial public offering, as early as Tuesday due to exceptionally high demand.

The world's leading social media site has been drumming up strong interest ahead of its planned opening on Friday 18th May.

The demand has led to Facebook increasing share prices from $28-35, to between $34 and $38.

Facebook is now expected to float on the stock market at over $100 billion, dwarfing that of rival Google which opened to less than $2 billion in 2004.

Despite such a high valuation, there are still concerns about the company's ability to make money through its mobile applications.

Advertising currently accounts for 82 per cent of Facebook's revenue, but more and more of the website's 900 million users are logging in on advert-free mobile applications.

Facebook is currently seeking other ways of generating revenue, with the announcement of its own app store, as well as a current trial in New Zealand of charging users to promote their own posts.