In 1997, together with Gus Attridge, he co-founded Aspen Pharmacare, a public company traded on the Johannesburg Stock Exchange. It has become the largest Producer of generic medicines on the African continent. He serves as its chief executive and Gus Attridge as its deputy chief executive, and serves on its board of Directors. In 2011, he was worth US$640 million, becoming one of Africa's 40 richest people. His stock portfolio went up 75% in 2013. He is now worth US$1.4 billion.