American business tycoon Warren Buffett has finally joined the exclusive $100 billion club that includes Elon Musk, Jeff Bezos and Bill Gates.

The 90-year-old is the chairman of investment firm Berkshire Hathaway, which has seen its shares rise to a record level this year.

On Wednesday his net worth edged above $100 billion for the first time.

Regarded as the world's most successful investor, Mr Buffett has given away billions of his wealth to charity.

While Mr Buffett has been a fixture at the top of the world's wealth rankings for decades, his wealth hasn't topped $100 billion until now.

One reason is his sizeable charitable donations - he has given away more than $37 billion in Berkshire Hathaway stock since 2006.

Mr Buffett is a co-founder of the Giving Pledge, a campaign to encourage billionaire philanthropy. Mackenzie Scott, ex-wife of Amazon founder Jeff Bezos, has also signed up to the pledge and gave away more than $4 billion of her fortune in just four months last year.

The fifth member of the exclusive cohort is LVMH's Bernard Arnault and his family.

Facebook co-founder Mark Zuckerburg has just slipped out of the exclusive list, according to the Forbes real-time billionaires list.

Mr Buffett's net worth comes almost entirely from owning about one-sixth of Berkshire Hathaway, a roughly $600 billion company.

Its share price is up 15% this year, surpassing $400,000 a share. The investment firm had been struggling in recent years to find deals to spark its growth given its sheer size.

The Omaha-based company is a major shareholder in Apple and other tech stocks that have seen their values surge during the pandemic.

Berkshire Hathaway was a failing textile company before Mr Buffett took control of it 1965. It now owns more than 90 businesses.