The Aiyagari model with liquidity shoch

Neste trabalho é desenvolvida uma versão do modelo de Aiyagari (1994) com choque de liquidez. Este modelo tem Huggett (1993) e Aiyagari (1994) como casos particulares, mas esta generalização permite dois ativos distintos na economia, um líquido e outro ilíquido. Usar dois ativos diferentes implica em dois retornos afetando o "market clearing", logo, a estratégia computacional usada por Aiyagari e Hugget não funciona. Consequentemente, a triangulação de Scarf substitui o algoritmo. Este experimento computacional mostra que o retorno em equilíbrio do ativo líquido é menor do que o retorno do ilíquido. Além disso, pessoas pobres carregam relativamente mais o ativo líquido, e essa desigualdade não aparece no modelo de Aiyagari.A version of the Aiyagari (1994) model with a liquidity shock is developed in this work. The model has Huggett (1993) and Aiyagari (1994) as particular cases, but the general one allows for two assets in the economy, a liquid and an illiquid one. Using two di erent assets implies in two returns clearing the market, so the computational strategy used by Aiyagari and Hugget does not work here. Therefore, Scarf's triangulation algorithm replaces it. Our computational experiment shows that the equilibrium return of the liquid asset is smaller than the return of the illiquid one. In addition, poor people carry relatively more of the liquid asset, which is a source of inequality that is not present in the Aiyagari's work

Preventing Bank Runs

Diamond and Dybvig (1983) is commonly understood as providing a formal rationale for the existence of bank-run equilibria. It has never been clear, however, whether bank-run equilibria in this framework are a natural byproduct of the economic environment or an artifact of suboptimal contractual arrangements. In the class of direct mechanisms, Peck and Shell (2003) demonstrate that bank-run equilibria can exist under an optimal contractual arrangement. The difficulty of preventing runs within this class of mechanism is that banks cannot identify whether withdrawals are being driven by psychology or by fundamentals. Our solution to this problem is an indirect mechanism with the following two properties. First, it provides depositors an incentive to communicate whether they believe a run is on or not. Second, the mechanism threatens a suspension of convertibility conditional on what is revealed in these communications. Together, these two properties can eliminate the prospect of bank-run equilibria in the Diamond-Dybvig environment

Is money essential? An experimental approach

Monetary exchange is deemed essential when better incentive-compatible outcomes can be achieved with money than without it. We study essentiality both theoretically and experimentally, using finite-horizon monetary models that are naturally suited to the lab. We also follow the mechanism design approach and study the effects of strategy recommendations, both when they are incentive-compatible and when they are not. Results show that output and welfare are significantly enhanced by fiat currency when monetary equilibrium exists. Also, recommendations help if they are incentive-compatible but not much otherwise. Sometimes money is used when it should not be and we investigate why, using surveys and measures of social preferences