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...

We analyse a card payment system to assess the economic impact of the interchange fee. This fee is paid by the bank of the merchant, the acquirer, to the bank of the consumer, the issuer. We build up a mode in order to explore whether the interchange fee can enhance the participation to the...