The martingale theory of price bubbles defines an asset bubble to exist when the asset's price process is a strict local martingale, that is, a local martingale that is not a martingale. Using this definition of a price bubble, for continuous semimartingales, we characterize the conditions under...

This paper studies an equilibrium model with heterogeneous agents, asset price bubbles, and trading constraints. Market liquidity is modeled as a stochastic quantity impact from trading on the price. Bubbles are larger in liquid markets and when trading constraints are more binding. Systemic...