Jim Simons Stood By One Quant Investing Rule That Helped Him Earn 66% Returns For 30 Years, 'You Just Stick With It, And It Worked'

Jim Simons, a mathematician turned investor with remarkable success, once mentioned to a group of students that the only rule he’s stood by while investing is not letting gut instinct interfere with his math.

What Happened: In a newly resurfaced 2014 talk at San Francisco State University, the Renaissance Technologies founder explained the hedge fund's cardinal rule: "We never override the computer. No one ever comes in any day and says the computer wants to do this and that's crazy and we shouldn't do it … You just stick with it, and it's worked."

The comment offers a rare window into the firm behind the Medallion Fund, whose returns, roughly 66 percent a year before fees between 1988 and 2018, have made Simons a legend on Wall Street. Renaissance builds thousands of predictive signals from decades of market data, then lets algorithms trade automatically across stocks, futures and currencies.

Human second‑guessing, Simons said, would break the historical testing that underpins every line of code: "You can't study the past and wonder whether the boss was gonna come in and change his mind."

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Quant funds routinely tweak models, but outright vetoes risk injecting bias and erasing the statistical edge. Simons, a former National Security Agency code‑breaker and Stony Brook University math chair, argued that discipline mattered more than any single signal. "The only rule is you never hit the override button," he told students, calling it the bedrock of Renaissance's culture.

What To Know: Mathematician‑turned‑hedge‑fund legend, Simons, was born in Newton, Massachusetts, in 1938, earned a Ph.D. from Berkeley, co‑created Chern‑Simons theory, chaired Stony Brook's math department, and later founded Renaissance Technologies, whose model‑driven trades rewrote Wall Street records.

With his wife Marilyn, Simons launched the Simons Foundation in 1994, channeling billions to math, basic science, and autism research. The billionaire philanthropist died in New York at 86, leaving three children, five grandchildren, and a great‑grandchild.

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