Facebook may let its employees sell up to $1 billion of their shares to institutional investors at a price that values the company at about $60 billion, an influential industry blog reported.

Facebook is pondering the move after entertaining approaches from a number of major institutions interested in investing in the world's largest social network, the All Things Digital technology blog cited sources as saying on Thursday.

That valuation would surpass previous measures. Last month, the company founded by Mark Zuckerberg in a Harvard dorm room raised $1.5 billion of financing in a round led by Goldman Sachs, which valued it at $50 billion.

Facebook, whose online service counts more than a half a billion users worldwide, is expected to possibly go public around 2012.

A Facebook spokesman declined to comment.

Investors have been eager to buy shares of Facebook before then and have gone to private exchanges, where shareholders like venture capitalists and former employees have put some of their stock up for sale.

Facebook tightly restricts current employees from selling their shares on private exchanges, making it difficult for them to cash in on the company's success.

In 2009, Facebook arranged for Russian investment firm Digital Sky Technologies to purchase at least $100 million of common shares from its employees. DST was also part of the deal led by Goldman Sachs in January.

Last year, Facebook overtook Google Inc to become the most visited website in the United States, according to online analytics firm Experian Hitwise.

The company is generating profits at a faster-than-expected rate, according to a document distributed by Goldman Sachs last month.

Facebook is among several fast-growing privately held Web companies, including Twitter, Zynga and Groupon, that investors have been anxious to buy into ahead of potential public listings.

But liquidity on private exchanges has been low and since Facebook so far has not been forced to publicly report its earnings there is little transparency for investors.

(Reporting by Edwin Chan and Noel Randewich; Editing by Maureen Bavdek and Richard Chang)