There is an extensive literature claiming that it is often difficultto make use of arbitrage opportunities in financial markets. Thispaper provides a new reason why existing arbitrage opportunitiesmight not be seized. We consider a world with short-lived securities,no short-selling constraints...

The evidence from many experiments suggests that people are heterogeneous with regard to their abilities to make rational, forward looking, decisions. This raises the question when the rational types are decisive for aggregate outcomes and when the boundedly rational types shape aggregate...