These notes review two simple heterogeneous agent models in economics and finance. The first is a cobweb model with rational versus naive agents introduced in Brock and Hommes (1997). The second is an asset pricing model with fundamentalists versus technical traders introduced in Brock and...

This paper surveys work on dynamic heterogeneous agent models (HAMs) in economics and finance. Emphasis is given to simple models that, at least to some extent, are tractable by analytic methods in combination with computational tools. Most of these models are behavioral models with boundedly...

An information-theoretic thought experiment is developed to clarify why the maximum entropy methodology is appropriate for predicting the equilibrium state of economic systems. As a first step, object allocation problems, modeled as knapsack problems, are shown to be equivalent to congestion...

We consider discrete-time dynamic principal-agent problems with continuous choice sets and potentially multiple agents. We prove the existence of a unique solution for the principal's value function only assuming continuity of the functions and compactness of the choice sets. We do this by a...

The maximum entropy methodology is applied to the Schelling model of urban segregation in order to obtain a reliable prediction of the stable configuration of the system without resorting to numerical simulations. We show that this approach also provides an implicit equation describing the...

Dybvig ( 1988a , 1988b ) solves in a complete market setting the problem of finding a payoff that is cheapest possible in reaching a given target distribution (“cost-efficient payoff”). In the presence of ambiguity, the distribution of a payoff is, however, no longer known with certainty. We...

We provide simple examples to illustrate how wealth-driven selection works in asset markets. Our examples deliver both good and bad news. The good news is that if individual assets demands are expressed as a fractions of wealth to be invested in each asset, e.g. because traders maximize an...

In a complete market for short-lived assets, we investigate long run wealth-driven selection on a general class of investment rules that depend on endogenously determined current and past prices. We find that market instability, leading to asset mis-pricing and informational efficiencies, is a...

We study the impact of diverse beliefs on conduct of monetary policy. We use a New Keynesian Model solved with a quadratic approximation. Aggregation renders the belief distribution an aggregate state variable. Diverse expectations change standard results about a smooth trade-off between...

This paper studies the effect of new fund flows on investment behavior and the resulting equilibrium price of risk. The Small Fund Industry model shows equilibria with overinvestment in unprofitable and underinvestment in profitable investment opportunities. The Large Fund Industry model derives...