We provide a model for why high beta assets are more prone to speculative overpricing than low beta ones. When investors disagree about the common factor of cash-flows, high beta assets are more sensitive to this macro-disagreement and experience a greater divergence-of-opinion about their payoffs. Short-sales constraints for some investors such as retail mutual funds result in high beta assets being over-priced. When aggregate disagreement is low, expected return increases with beta due to risk-sharing. But when it is large, expected return initially increases but then decreases with beta. High beta assets have greater shorting from unconstrained arbitrageurs and more share turnover. Using measures of disagreement about stock earnings and economic uncertainty, we verify these predictions. A calibration exercise yields reasonable parameter values.
Hong acknowledges support from the National Science Foundation through grant SES-0850404. Sraer gratefully acknowledges support from the European Research Council (Grant No. FP7/2007-2013 - 249429) as well as the hospitality of the Toulouse School of Economics. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.
Harrison Hong & David A. Sraer, 2016. "Speculative Betas," Journal of Finance, American Finance Association, vol. 71(5), pages 2095-2144, October. citation courtesy of