James Simons, Medallion Hedge Fund and Renaissance Technologies, president testifies about the risks that hedge funds pose in the financial markets, before the House Oversight Committee, and HEARING BEFORE THE SENATE PERMANENT SUBCOMMITTEE ON INVESTIGATIONS by Jonathan Mayers, Counsel on Behalf of Renaissance Technologies LLC...

The most successful hedge fund in history describe their business model as a positive expected value game.

The model developed by Renaissance for Medallion and Medallion with barrier options makes predictions that are profitable only slightly more often than not. Moreover, the predicted price movements can be easily overwhelmed by external events. To compensate for these factors, the model generates a large number of recommendations, so that by virtue of the mathematical principle known as the law of large numbers, the variability of the returns produced by the model is greatly reduced.