Isabel dos Santos, the oldest daughter of Angola's longtime president, Jose Eduardo dos Santos, is the richest woman in Africa. Though her representatives deny that her holdings have any connection with her father, research in Angola shows that President dos Santos has transferred stakes in several companies to his daughter. Her most valuable asset -- worth at least $1.1 billion -- is a 25% stake in Unitel, one of Angola's two mobile phone networks, where Isabel dos Santos is a board member. She also sits on the board of Angola's Banco BIC, where she also has a 25% stake. In Portugal, she owns a slice of former state oil company GALP in a partnership with Angolan state oil company Sonangol and Portuguese billionaire Americo Amorim. She owns 25% of ZON Optimus, a listed Portuguese cable TV company formed by the merger of ZON Multimedia and Optimus; and just under 20% of Banco BPI, one of Portugal's largest publicly traded banks. Forbes listed Isabel dos Santos' net worth at $500 million a year ago. Her net worth has ballooned since then primarily due to continued research into her holdings by Forbes and Angolan journalist Rafael Marques de Morais. Her first business, opened in 1997 when she was 24, was a restaurant called Miami Beach in Luanda, the Angolan capital.