Facebook chief executive Mark Zuckerberg has joined Bill Gates and Amazon founder Jeff Bezos as one of the world's three richest men.

According to calculations by Bloomberg, the 34-year-old has overtaken Warren Buffett to become the world's third-richest person as Facebook's shares rose by 2.4 per cent.

Zuckerberg is now worth $81.6 billion, nearly $400 million more than Buffett, according to the rankings.

Bezos is classified as the world's richest man with a personal fortune estimated to be worth $141 billion, followed by Bill Gates with an estimated $94.2 billion.

Zuckerberg's climb means that, for the first time ever, the world's three richest people are all technology leaders.