The duo of John Overdeck and David Siegel founded Two Sigma Advisors in 2001 along with Mark Pickard, who is now retired. John Overdeck was formerly the managing director at D.E. Shaw & Co., where David Siegel also worked as Chief Information Officer. Mr. Siegel worked at Paul Tudor's Tudor Investment Corp, and hence, has brought his algorithmic experience over to Two Sigma. According to the latest estimates, Two Sigma has over $20 billion in assets under management.