Recent studies find that transactions volume and volatility spread of exchange-traded single-stock options predict the underlying stock’s future returns. Most of the firms with exchange-traded options have large market capitalization and are actively traded. It is a puzzle why it takes days...

This paper incorporates model ambiguity into the traditional hedge fund models to explore how ambiguity influences the manager's investment strategy, risk attitude and compensation structure. We find the manager is ambiguity aversion. Model ambiguity enhances her level of endogenous risk...