Through extending a standard Grossman and Stiglitz (1980) noisy rational expectations economy by a heterogeneous signal structure with signal-specific differences in uncertainty, we show that price momentum as well as reversal are not intrinsically at odds with rational behavior. Differences in...

α (“Alpha”) has symbolic importance on the investments side of finance. That is, a fundamental pillar of modern finance theory is the risk-return relation, and traditionally alpha is taken to represent the degree of “mispricing” in asset returns. But, such an interpretation is not...

This paper finds that the majority of stock price movements remain unexplained after controlling for both public and private information. This suggests that economists' inability to explain asset price movements is the result of either noise or naive asset pricing models.

The quality of information in financial asset markets is often hard to estimate. This paper analyzes information transmission in asset markets when agents treat information of unknown quality as ambiguous. We consider a market with risk-averse informed investors, risk-neutral competitive...

Biographical note: DuffieDarrell: Darrell Duffie is the Dean Witter Distinguished Professor of Finance at Stanford University's Graduate School of Business. His books include "How Big Banks Fail and What to Do about It" and "Dynamic Asset Pricing Theory" (both Princeton).