Aggregate Alpha in the Hedge Fund Industry: A Further Look at Best Ideas

This article is an examination of the stock-picking behavior of nearly 1,500 hedge funds using regulatory mandated position-level data from the SEC (Form 13F). Using data from June 1999 to December 2018, abnormal excess alpha is found on both a gross and dollar basis. Breaking the 20-year sample into two periods, the authors note a significant decline in gross alpha after the 2008 global financial crisis. In contrast, dollar alphas remain economically and statistically significant. This finding coincides with an increase in aggregate assets in the post-crisis period, suggesting asset growth may be impeding gross alphas. To test this hypothesis, the authors analyze the Best Ideas within manager portfolios. They find no significant difference between the alphas generated by managers’ Best Ideas and the rest of their portfolios, suggesting asset growth is not a significant determinant of alpha deterioration. These findings broadly contrast with prior studies conducted on mutual funds, suggesting differences in portfolio construction and incentive effects.