The billionaire owner of a Bermuda-based fund management company has been named as the wealthiest man in South Africa and the second-wealthiest in the entire continent.Allan Gray, the chairman of asset management firm Orbis rocketed into magazine Ventures Africa’s annual rich list with a fortune estimated at $8.5 billion.It is his first appearance on the list — largely because his business empire has never been publicly quoted so it was difficult to estimate his total worth.Mr Gray, 75, who lives in South Africa, founded the Front Street firm in 1989, which is run by his son William and employs around 80 people.Mr Gray founded Orbis after working in the US, South Africa and London.Mr Gray pushed diamond mining tycoon Nicky Oppenheimer from the top spot in South Africa. Mr Oppenheimer, who family owned a large share of mining firm De Beers, the biggest producer of diamonds in the world, fell to fifth place.His Allan Gray Ltd investment management firm is the largest privately-owned firm of its type in South Africa and retains close links with the Bermuda operation.Mr Gray founded the firm as a one-man company in Cape Town in 1973 and pioneered performance related investment management fees in Southern Africa.The firm now manages more than $10 billion in investors funds.He was pipped at the post for richest man in Africa by Nigerian mining-to-retail entrepreneur ALiko Dangote, who is worth $20.2 billion.Mr Gray was born and brought up in East London on the south-east coast of South Africa and qualified as a chartered accountant before achieving a Master’s degree at the prestigious Harvard Business School.Mr Gray in 2007 gave $130 million to fund a charity to give bursaries to South African high school students — at the time, the largest ever single donation in South African history.