Renaissance Technologies LLC (also known as RenTech[4] or RenTec[5]) is an American hedge fund based in East Setauket, New York,[6] on Long Island, which specializes in systematic trading using quantitative models derived from mathematical and statistical analysis.

[18] James Simons founded Renaissance Technologies following a decade as the Chair of the Department of Mathematics at Stony Brook University.

[21] Renaissance Technologies' hedge fund has employed mathematical models to analyze and execute trades, many of them automated.

The book The Quants describes the hiring of speech recognition experts, many from IBM, including the current leaders of the firm.

[22] Renaissance employs specialists with non-financial backgrounds, including computer scientists, mathematicians, physicists, signal processing experts and statisticians.

[25] Mathematician Isadore Singer referred to Renaissance's East Setauket office as the best physics and mathematics department in the world.

[27] The firm is known for low personnel turnover[28] and for requiring its researchers to agree to intellectual property obligations by signing non-compete and non-disclosure agreements.

[29] In 1978, Simons left academia and started a hedge fund management firm called Monemetrics in a Long Island strip mall.

Simons started recruiting some of the mathematicians and data-modeling types from his days at the Institute for Defense Analysis (IDA) and Stony Brook University.

He worked with Sandor Straus, Jim Simons and another consultant, Henry Laufer, to overhaul Medallion's trading system over the course of six months.

In 1990, Berlekamp led Medallion to a 55.9% gain, net of fees, and then returned to his duties as a Berkeley professor after selling out to Simons at six times the price for which he had bought his Axcom interests sixteen months earlier.

[33] "Since 1988, his flagship Medallion fund has generated average annual returns of 66% before charging hefty investor fees—39% after fees—racking up trading gains of more than $100 billion.

Warren Buffett, George Soros, Peter Lynch, Steve Cohen, and Ray Dalio all fall short.

[14] Renaissance Institutional Equities Fund had difficulty with the higher volatility environment that persisted throughout the end of the summer of 2007.

Simons said other hedge funds have been forced to sell positions, short-circuiting statistical models based on the relationships among securities.

According to an article in Bloomberg in November 2020,[41] Renaissance saw a decline of about 20% through October in its long-biased fund, according to a person familiar with the matter.

The firm, founded by former codebreaker Jim Simons, told investors that its losses are due to being under-hedged during March’s collapse and then over-hedged in the rebound from April through June.

“It is not surprising that our funds, which depend on models that are trained on historical data, should perform abnormally (either for the better or for the worse) in a year that is anything but normal by historical standards,” Renaissance told clients in a September letter seen by Bloomberg.From December 1, 2020 to February 1, 2021, according to Bloomberg, clients (LPs) had withdrawn $5 billion from the fund.

The company cited a number of reasons for this, including the fact that "institutional investors may alter their trading activity to avoid public disclosure".

Because Medallion could claim that it owned just one asset – the option – and held it for more than a year, investors could declare their gains to be long-term investments.

In September 2021, Simons, Mercer, and other Renaissance executives agreed to pay up to $7 billion in taxes and penalties to settle the dispute with the IRS.

[44][45] According to OpenSecrets, Renaissance was the top financial firm contributing to federal campaigns in the 2016 election cycle, donating $33,108,000 by July.