MARK HENDERSON began his career in New York with Rheem International, Inc., a subsidiary of City Investing Corp. He was seconded by Rheem to South Africa between 1969 and 1973 to establish their South African subsidiary.
In 1974 he joined Panmure Gordon & Co., members of the London Stock Exchange. He became an individual member of the London Stock Exchange in 1979 and a partner of Panmure Gordon & Co. in 1981.
Panmure Gordon & Co. was acquired by NationsBank Corp. in 1986. In that year he became a director of NationsBank (Europe) Ltd. and a member of the Executive Committee of Panmure Gordon & Co., Ltd.
He joined W.P. Stewart in 1998 and acted as Deputy Managing Director of W.P. Stewart & Co., Ltd. and Co-Chairman of W.P. Stewart Asset Management (Europe) Ltd until leaving in December 2007.