Jim Simons is an American mathematician, hedge fund manager, and philanthropist, best known for founding the quantitative investment firm Renaissance Technologies. Born on April 25, 1938, he earned a Ph.D. in mathematics from University of California, Berkeley and worked as a codebreaker for the U.S. National Security Agency during the Cold War. Simons revolutionized the finance industry by applying mathematical models and algorithms to trading, leading to significant profits for his firm. His flagship fund, the Medallion Fund, is famous for its high returns and secretive trading strategies, making him one of the wealthiest individuals in the world.