The Medallion Fund, managed by Renaissance Technologies, is widely recognised as one of the best-performing Hegde Funds in history. With annualised returns (after fees) approaching 40% since its inception, this fund has acquired legendary status in the financial world. This phenomenal success is mainly due to the algorithms developed by former mathematics professor Jim Simons, whose innovative approach to trading has transformed the financial sphere. Find out more below.

 About Jim Simons

Jim Simons was born on April 25, 1938, in Newton, Massachusetts. From an early age, Simons demonstrated an exceptional talent for mathematics, a passion that would shape his academic and professional life. He pursued his graduate studies at the Massachusetts Institute of Technology (MIT), where he earned a B.S. in mathematics. Simons went on to earn his doctorate at the University of California, Berkeley, in 1961, aged just 23. A few years later, in 1964, he worked as a decryptor for the National Security Agency during the Vietnam War. Simons' academic career was marked by important contributions to the field of mathematics, particularly geometry and topology. He has taught at MIT and Harvard University. His research in differential geometry earned him widespread recognition and respect in the mathematical community.

Although already an accomplished academic, Simon's interest in applying mathematical principles to real-world problems led him to explore the financial markets. Thus, in 1978, in a Long Island shopping mall, he founded Renaissance Technologies (RenTec), initially named Monometrics before being renamed in 1982. Simons' transition from academia to hedge funds was not a smooth one. RenTec's early years were marked by strategic recruitment and experimentation, as Simons and his team strove to perfect their trading strategies. Skilled as he was, Simons needed a team to carry out this massive project, and his first key hire began with his former mathematician colleague, Leonard E. Baum. Simons asked him to spend a day at Monometrics to help create a currency trading system. Baum wasn't interested in trading but agreed to do an old friend a favour.

The story soon changed, however, as in 1979, the former, hooked on trading, gave up his university career. Baum, a proponent of short-term forecasting in chaotic environments, was making so much money trading various currencies and using his intuition that trying to create a quantitative style of trading seemed a waste of time. His strategy was to make an investment and hold it until it appreciated, however long that took. This stubborn strategy enabled him to overcome market turbulence and accumulate over $43 million in profits between 1979 and 1982. Simons described him as “having the buy-low part, but not always having the sell-high part”. Holding on to investments in this manner eventually led to losses; when the value of Baum's investments fell by 40%, a clause in his contract with Simons was triggered, forcing Simons to sell all Baum's investments and end their business partnership. Ultimately, Baum would leave the firm in 1984 amid steep losses. The setback was so significant that Simons halted his firm’s trading and even considered giving up trading altogether.

However, Simons kept trying, amassing price data, developing algorithms capable of predicting the markets next move, and setting up trading models that could run on their own. Simons now also had the help of James Ax, a mathematics PHD, who was instrumental in getting the firm off the ground. In 1988, after having been trading in the futures markets for a few years, Ax and Simons established the Medallion Fund, which would later become RenTec’s flagship fund. Despite the success the fund is renowned for today, the early days weren’t that easy. In its first year the fund delivered a net return of 9% while the S&P500 was up over 16% and in its second year the fund lost a 4% while the S&P500 was up over 30%. The tensions that mounted within the company as a result, led to Ax being bought out of the firm in 1989.

Subsequently, Simons brought in Elwyn Berlekamp to help redesign the company’s trading system from the ground up to return to profitability. Berlekamp was a prominent game theorist, having received a PHD in electrical engineering from MIT and made significant contributions to mathematics and coding theory. His strategies leveraged a deep understanding of the Kelly criterion, a method for determining the optimal size of a series of bets to maximize the expected value of the logarithm of wealth. In 1989 he was put in charge of the Medallion fund, leading to the funds first great success, delivering a 59% net return that same year.

Two additional hires that were critical to the fund’s success were Robert Mercer and Peter Brown. Mercer and Brown found their way into Renaissance Technologies after being lured away from IBM by Simons in 1993. The pair were involved in implementing a new trading system, that marked the beginning of a period of outstanding performance. Mercer, on probabilities and executing strategy: “We’re right 50.75% of the time (…) but we’re 100% right 50.75% of the time, you can make billions that way”. Their contributions to the firm eventually led them to the roles of Co-CEO in 2010. Peter brown has since taken over the role of sole CEO, after Mercer’s resignation in 2017.