We develop a simple model of the exchange rate in which agents optimize their portfolio and use different forecasting rules. They check the profitability of these rules ex post and select the more profitable one. This model produces two kinds of equilibria, a fundamental and a bubble one. In a...

The rational expectations efficient market model of the exchange rate has failed empirically. In this paper we develop a model of the exchange rate in which agents use simple forecasting rules. Based on an ex post evaluation of the relative profitability of these rules they decide whether to...