A great book about RenTec and Jim Simons came out recently: The Man Who Solved the Market: How Jim Simons Launched the Quant Revolution. Everyone in the industry worships Simons and RenTec as practically god-like. What they've managed to do shouldn't really be possible and is out of this world. According to Wikipedia over a 20 year period between 1994 and 2014, RenTec realized an 71.9% annualized return in their internal Medallion fund. And before anyone says that's a fluke, let's calculate the probability of such a "fluke" using some simplifying assumptions:
1. S&P 500 returns are log-normally distributed with a log-return of 10% and volatility of 10%
2. RenTec made a mean annualized return of 71.9% over 20 years
3. The returns of RenTec are independent from year to year
We get a PAnd before someone says that it's a scam, there's no outside investors in the Medallion fund anymore, so if it is a scam, they would only be scamming their own employees. And if that was the case, I think we would know.