Facebook has landed a $500 million (£320 million) investment from Goldman Sachs and Digital Sky Technologies (DST), valuing the social networking site at $50 billion (£32.3 billion).
The investment values Facebook at roughly twice that of Internet giants Yahoo or eBay, but still some way off Google, which is valued at $190 billion (£122 billion).
The deal underlines an impressive 12 months for the social network, which has already added over half a billion users and, according to figures from Internet traffic analysts Experian Hitwise, has surpassed Google to become the most visited site in the world.
Facebook, founded by chief executive Mark Zuckerberg, has so far resisted floating its shares on the stock market. Zuckerberg last year dismissed rumours of a public floatation, saying that he did not see such a thing as a major goal for the company.
The Press Association reports that, according to Wedbush Morgan analyst Lou Kerner, if Facebook were to go public, it could expect to trade at around $100 billion (£65 billion).