We analyze the performance of irrational investors, who mistake expected returns of assets in a multi-asset economy. Mistakes by probabilistically unsophisticated investors that a priori seem small lead to severe underperformance compared with rational investors, under general conditions. Our...

We define the concept of market beliefs in an economy with disagreement, such that equilibrium in a representative agent economy with market beliefs is equivalent to equilibrium in the disagreement economy. In general, the mapping from individual agent beliefs to market beliefs is complex and...

In a production economy, in which agents have heterogeneous beliefs and a social planner has incomplete knowledge about which beliefs are correct, we introduce the concept of Incomplete Knowledge (IK) efficiency. IK-inefficient allocations can be improved upon without taking a stand on which...