Common Knowledge and the Value of Defending a Fixed Exchange Rate ? An Explanation of a Currency Crisis

Based on a framework originally developed by Morris and Shin (1995), this model shows how a currency crisis may be triggered by a lack of common knowledge regarding government type. Speculators receive noisy differential information concerning the value a government places on maintaining an exchange rate parity. When this value falls in a particular region, the government will abandon the peg if a sufficient number of speculators sell their currency. However, it will maintain the peg if no attack is launched. This paper shows that, in this region, it is always optimal for the speculators to attack the currency thereby forcing a devaluation