We propose a new theory of systemic risk based on Knightian uncertainty (or "ambiguity"). We show that, due to uncertainty aversion, beliefs on future asset returns are endogenous, and bad news on one asset class induces investors to be more pessimistic about other asset classes as well. This...

We present a novel source of disagreement grounded in decision theory: ambiguity aversion. We show that ambiguity aversion generates endogenous disagreement between a firm's insider and outside shareholders, creating a new rationale for corporate governance systems. In our paper, optimal...