Uncertainty, Disagreement and the Idiosyncratic Volatility Puzzle
Job market paper
Abstract
Why do stocks with high idiosyncratic volatility earn low returns? Greater fundamental volatility raises both uncertainty and disagreement, with disagreement increasing proportionately more. Under short sale constraints, these forces have opposing effects on prices. We establish a sharp common prior bound relating uncertainty and disagreement and characterize an exact nonlinear rational expectations equilibrium with risk-averse investors, continuously varying positions, and learning from prices. Greater fundamental volatility can raise prices when ownership is sufficiently narrow. Consistent with the theory, we find empirically that the negative relationship between idiosyncratic volatility and subsequent returns strengthens as borrowing costs rise and ownership breadth declines, and that disagreement accounts for much of the anomaly around earnings announcements, when firm-specific public information is revealed.
