Simon is currently the Executive Chairman of GEMS, and a board director of the Cheung Kong Holdings Ltd., Orient Overseas (International) Ltd., Wing Tai Properties Ltd., Arnhold Holdings Ltd., Richemont SA, Essar Energy plc, Omnicorp Limited and IRC Limited.
He is now chairman of Gulf Keystone Petroleum and was formerly the chairman of Glencore. He has in the past served on boards and held advisory positions with a number of companies such as Vodafone, Tommy Hilfiger Corporation, Vivendi Universal, Usinor SA, Hermes, General Electric (USA), China National Offshore Oil Corporation (CNOOC), Macquarie Bank, N.M. Rothschild, and Bain (the consultancy company). He continues to serve on the advisory board of Lightbridge Corporation (USA), and was on the Development Advisory Board of Imperial College, London.
Earlier in he career, Simon was the Executive Chairman of the Deutsche Bank Group in Asia. He then established his own company, GEMS, a mid-sized investment group operating across Asia.
He was the oldest person to reach the south pole unsupported, and is a keen explorer.