We develop a theory of innovation waves, investor sentiment, and merger activity based on Knightian uncertainty. Uncertainty-averse investors are more optimistic on an innovation when they can make contemporaneous investments in multiple uncertain projects. Innovation waves occur when there is a...

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...