Hedge Funds summarizes the academic research on hedge funds and commodity trading advisors. The hedge fund industry has grown tremendously over the recent years. According to some industry estimates, hedge funds have increased from $39 million in 1990 to about $972 million in 2004 and the total number of hedge funds has gone up from 610 to 7,436 over the same period. At the same time, hedge fund strategies have changed significantly. In 1990 the macro strategy dominated the industry while in 2004 the equity hedge strategy had the largest share of the market. There has also been a shift in the type of investor in hedge funds. The first part of this book summarizes hedge fund performance, including comparisons of risk-return characteristics of hedge funds with those of mutual funds, factors driving hedge fund returns, and persistence in hedge fund performance. The second part reviews research regarding the unique contractual features and characteristics of hedge funds and their influence on the risk-return tradeoffs. The third part reviews the role of hedge funds in a portfolio including the extent of diversification benefits and limitations of standard mean-variance framework for asset allocation. Finally, the authors summarize the research on the biases in hedge fund databases.