Endogenous diversification in a market with incomplete information generates a state-dependent premium for bearing idiosyncratic risk because time series variation in average idiosyncratic risk affects the disutility of under-diversification. This idea delivers a metric that maps the marginal disutility of under-diversification to the covariance of idiosyncratic risk with average idiosyncratic risk. The metric helps explain thecross-section of returns in the US between 1973 and 2014, especially in periods of low average idiosyncratic risk. In such periods, portfolios tests generate intercepts from three and five-factor models that are economically large, and present in both small and large capitalization stocks. We observe similarly large intercepts in markets outside the US, particularly in large stocks.

About Sunil Wahal

Dr. Sunil Wahal is the Jack D. Furst Professor of Finance at Arizona State University’sW. P. Carey School of Business. Before joining the ASU faculty in 2005, Dr. Wahal was on the faculty at the Goizueta Business School, Emory University, and at the Krannert School of Management, Purdue University. He received his Ph.D. in Finance from University of North Carolina, Chapel Hill in 1995. Dr Wahal’s research focuses on trading issues (market microstructure), short and long-horizon trading strategies, and delegated portfolio management for mutual funds and institutional investors. He has published extensively in the Journal of Finance, the Journal of Financial Economics, the Review of Financial Studies and numerous other journals. He is a consultant to Dimensional Fund Advisors, advises a number of investment committees, and regularly interfaces with practitioners in a variety of ways. He is a regular speaker at academic and practitioner conferences.

More information about Sunil Wahal: webapp4.asu.edu/directory/person/825492

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