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 teaching math at Berkeley after selling out to Simons at six times the price for which he had bought his Axcom interests sixteen months earlier. Straus then took Berlekamp's place, running Medallion's revamped trading system, which returned 39.4% in 1991, 34% in 1992 and 39.1% in 1993, according to Medallion annual reports. The Medallion fund is considered to be one of the most successful hedge funds ever. From 1994 through mid-2014, it averaged a 71.8% annual return, before fees. The fund has been closed to outside investors since 1993 and is available only to current and past employees and their families. The firm bought out the last investor in the Medallion fund in 2005 and the investor community has not seen its returns since then. About 100 of Renaissance's some 275 employees are "qualified purchasers", meaning they generally have at least $5 million in assets to invest. The remaining are "accredited investors", generally worth at least $1 million. By 2000, the computer-driven Medallion fund had an average annual return of 34% after fees from its 1988 inception. Simons ran Renaissance until his retirement in late 2009. Between January 1993 and April 2005, Medallion only had 17 losing months and out of 49 quarters over the same period, Medallion had only three losing quarters. Between 1989-2005 Medallion had only one year showing a loss: 1989. During 2020 the Medallion fund surged 76%. Medallion as a retirement fund Renaissance Technologies terminated its 401(k) retirement plan in 2010 and employees' account balances were put into Individual Retirement Accounts. Contributions could be made to a standard Individual Retirement Accounts and then converted to a Roth IRA regardless of income. By 2012, Renaissance was granted a special exemption by the United States Labor Department allowing employees to invest their retirement money in Medallion arguing that Medallion had consistently outperformed their old 401(k) plan. In 2013, Renaissance's IRA plans had 259 participants whose $86.6 million contribution grew to $153 million that year without fees or annual taxes. Renaissance set up a new 401(k) plan, and in November 2014 the Labor Department allowed that plan to be invested in Medallion as well. Renaissance Institutional Equities Fund (RIEF) In 2005,