very little is known about them. The firm is known for its ability to recruit and retain scientific types, for having a personnel turnover that is nearly non-existent, and for requiring its researchers to agree to intellectual property obligations by signing non-compete and non-disclosure agreements. Monemetrics In 1978, Simons left academia and started a hedge fund management firm called Monemetrics in a Long Island strip mall. The firm primarily traded currencies at the start. It did not occur to Simons at first to apply mathematics to his business, but he gradually realized that it should be possible to make mathematical models of the data he was collecting. Monemetrics’ name was changed to Renaissance Technologies in 1982. 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. His first recruit was Leonard Baum, a cryptanalyst from IDA who was also the co-author of the Baum–Welch algorithm. When Baum abandoned the idea of trading with mathematical models and took to fundamental trading, Simons brought in algebraist James Ax from Cornell University. Ax expanded Baum's models for trading currencies to cover any commodity future and subsequently Simons set up Ax with his own trading account, Axcom Ltd., which eventually gave birth to the profitable fund — Medallion. During the 1980s, Ax and his researchers improved on Baum's models and used them to explore correlations from which they could profit. Medallion Fund In 1988, Renaissance established its most profitable fund, the Medallion fund (previously the Limroy Colombian fund), which used an expanded form of Leonard Baum's mathematical models improved by algebraist James Ax to explore correlations from which they could profit. Simons and Ax, who were classmates at the University of California, Berkeley, started Medallion, which they named after their awards in mathematics. The initial success of the company's models led Simons to base the fund's trades entirely on the models. By April 1989, however, peak-to-trough losses had mounted to about 30%. Ax claimed to have accounted for such a decline in his models and insisted on continuing to trade. Simons wanted to pause and reevaluate; Simons, as majority owner, prevailed, and Ax departed. Simons then asked Berkeley professor Elwyn Berlekamp to run Medallion. A consultant for Axcom whom Simons had first met at the IDA, Berlekamp had acquired most of Ax's stake in Axcom and became its CEO. He