James Simons, 68

$2.6bn, hedge funds

East Setauket, New York

James Simons, a Berkeley PhD, started his career as a mathematics teacher at Harvard and MIT and as a cryptanalyst (code-breaker) at the Institute for Defence Analyses at Princeton. In 1978, having dabbled in currency trading while teaching at the State University of New York at Stony Brook, he started his first private investment fund. Now his Renaissance Technologies Corp hedge fund management company, which employs more than 60 scientists to determine investment strategies by statistical modelling, is among the world's most successful. As if Simons' commercial achievements weren't enough, back in 1974 he co-authored a paper that introduced the breakthrough Chern-Simons theory to the world of geometry. Since the mid-1980s, it has gained significant prestige for its use in topological quantum field theory.