Several studies have put forward that hedge fund returns exhibit a nonlinear relationship with equity market returns, captured either through constructed portfolios of traded options or piece-wise linear regressions. This paper provides a statistical methodology to unveil such nonlinear features with respect to returns on benchmark risk portfolios. We estimate a portfolio of options that best approximates the returns of a given hedge fund, account for this search in the statistical testing of the nonlinearity, and provide a reliable test for a positive valuation of the fund. We find that not all fund categories exhibit significant nonlinearities, and that only a few strategies provide significant value to investors. Our methodology helps identify individual funds that provide value in an otherwise poorly performing category. Copyright © 2010 John Wiley & Sons, Ltd.