NEW YORK - MARK Zuckerberg, the 23-year-old founder of social networking site Facebook, is the youngest ever self-made billionaire, according to an annual list published by Forbes magazine.

'He is the youngest billionaire in the world right now and we also believe he is the youngest self-made billionaire in history,' said the magazine's Associate Editor Matthew Miller, unveiling this year's super-rich list.

The magazine put the former Harvard student's personal wealth at US$1.5 billion (S$2 billion), based on what it said was a conservative valuation of US$5 billion for Facebook and Mr Zuckerberg's estimated 30 per cent stake.

It played down speculation that the site could be worth as much as US$15 billion, which was based on Microsoft paying US$240 million for a 1.6 per cent stake in the company last year.

'Would it really fetch that much today? Some analysts - and a few Facebook investors - doubt it,' the magazine said. It said it based its valuation on Facebook's estimated annual sales of 150 million. -- AFP