Investment Decisions Under Ambiguity: Evidence from Mutual Fund Investor Behavior

This study provides novel evidence on the role of ambiguity aversion in determining the response of mutual fund investors to historical fund performance information. We present a model of ambiguity averse investors who receive multiple performance-based signals of uncertain precision about manager skill. A key implication of the model is that when investors receive multiple signals of uncertain quality, they place a greater weight on the worst signal. We find strong empirical support for this prediction in the data. Fund flows display significantly higher sensitivity to the worst performance measure even after controlling for fund performance at multiple horizons, performance volatility, flow-performance convexity, and a host of other relevant explanatory variables. This effect is particularly pronounced in the case of retail funds in contrast to institutional funds. Our results suggest that fund investor behavior is best characterized as reflecting both Bayesian learning and ambiguity aversion.