James Harris (Jim) Simons, Ph.D. is a cryptanalyst, mathematical physicist, academic, investment advisor, billionaire and philanthropist. In 1982, Simons founded Renaissance Technologies Corporation, a private investment firm based in New York with over $12 billion under management; Simons is still at the helm, as president, of what is now one of the world's most successful hedge funds. According to Institutional Investor magazine, Simons earned an estimated $1.5 billion in 2005 (the largest compensation among hedge fund managers that year ) and $670 million in 2004. Simons' most influential research involved the discovery and application of certain geometric measurements, and resulted in the Chern-Simons form (aka Chern-Simons invariants, or Chern-Simons theory). In 1974, his theory was published in Characteristic Forms and Geometric Invariants, co-authored with the differential geometer Shiing-Shen Chern. The theory has wide use in theoretical physics, particularly string theory. With an estimated current net worth of around $4 billion, he is ranked by Forbes as the 64th-richest person in America.