Isabel dos Santos, the eldest daughter of Angolan President Jose Eduardo dos Santos, is Africa's first woman billionaire, according to research by Forbes magazine.
Isabel dos Santos bought shares in several Portuguese companies in recent years, including a bank and a cable television company.
"Those stakes, combined with assets Isabel dos Santos owns in at least one bank in Angola, have pushed her net worth over the $1-billion mark ... making the 40-year-old Africa's first woman billionaire," the magazine reported on its website late on Wednesday.
Dos Santos is the main shareholder in ZON Multimedia, Portugal's largest cable television company.
She owns 28.8% through two other companies, Kento and Jadeium, according to Forbes' research.
Dos Santos has a 19.5% stake in Portuguese bank BPI, one of the largest trading on the country's stock exchange. The stake is reportedly worth $465-million.
Dos Santos also owns a quarter of Angolan bank BIC, estimated at $160-million, and a quarter of local telecommunications firm Unitel.
The Unitel stake alone is worth over $1-billion, analysts told the magazine.
Angola is the second-biggest oil producer in Africa, but its people are among the world's poorest. Most survive on less than $2 a day.
The eldest Dos Santos daughter grew up in London, where she studied mechanical and electrical engineering at King's College.
Her first business venture was a restaurant, Miami Beach, which she opened as a 24-year-old in Luanda.
She speaks several languages and is married to Congolese art collector Sindika Dokolo.
Discreet and media shy, she rarely appears in public.
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