Facebook has told investors in a $2 billion fundraising that its much-anticipated stock-exchange listing could come as early as April 2012, setting the stage for one of the most highly anticipated initial public offerings in recent years.

In a 100-page memorandum sent to Goldman Sachs ( GS) clients taking part in the cash call, the social network indicated that it would begin disclosing comprehensive financial information or go public by April next year, according to investors who received the document.

The news is likely to trigger a frenzy of activity among investors, banks and other advisers keen to be involved in a potential IPO. The fundraising values Facebook at $50 billion, more than listed companies with bigger revenue such as Time Warner ( TWX). The document shows that Facebook had revenue of $1.2 billion and profits of $355 million in the first nine months of 2010, investors said.

Facebook's revelation could also help to quell criticism that the company and Goldman structured the latest fundraising to get around U.S. rules requiring companies with more than 500 shareholders to publicly disclose financial information.

In the document, Facebook states that it expects to exceed the 500 investors threshold by 2011, forcing it to report financial data as listed companies do. The requirement removes one of the attractions of staying private and is often one cause for companies to go public.

Under U.S. law, companies must disclose financial data within 120 days of the end of the year in which they cross the 500-shareholder limit, putting a firm date on Facebook's likely move.

Facebook and Goldman, which is leading the fundraising and investing $375 million of its own funds into the company, had been criticized for setting a special purpose vehicle to allow the bank's clients and top executives to buy into Facebook.

Critics had charged that the structure was designed to comply with U.S. rules without forcing Facebook to reveal financial information because the special purpose vehicle could be treated as one investor, rather than a collection of hundred of shareholders.

Facebook and Goldman declined to comment.

One person close to the situation said even before the fundraising, Facebook had expected to cross the 500-shareholder limit in 2011. With more early employees leaving and selling their shares, it was seen as inevitable, this person said.

Having to disclose financial information was one factor that prodded Google ( GOOG) towards an IPO in 2004, said Lise Buyer, a former Google executive who managed the process. However, she said a far more important reason was Google's desire to give all investors equal access to the company.

"Google wanted to see all investors treated fairly, whether it's Goldman Sachs or farmer Joe," Buyer said. "Facebook has taken a 180-degree different approach so far."