First-generation models explain currency crises in terms of weakening macroeconomic fundamentals caused by the pursuit of policies that are incompatible with a' fixed exchange-rate regime. For example, expansionary fiscal policies (or recurrent budget deficits) leading to monetisation of the deficit can cause foreign exchange reserves to fall to critical levels. Speculators who want to make a profit can buy foreign exchange reserves, causing them to be exhausted and forcing the country to devalue or abandon the exchange-rate peg. The process of collapse of fixed exchange-rate regimes due to weakening macroeconomic fundamentals in Latin American economies incurring high levels of foreign debt in the 1970s, have been stylised in the first-
8 generation models.
Second-generation models differ from first- generation models by recognising the existence of nonlinear behaviour resulting in multiple equilibria. For instance, if an economy is not subject to shocks then the optimal equilibrium solution is the pursuit of a fixed exchange-rate policy. However, if the economy is subject to a severe shock (due to high unemploy- ment) then the government can engage in discretion- ary policy (devalue under sticky wages) and thereby renege on its commitment to a fixed exchange-rate
9 regime in order to achieve short-run welfare gains.
Such time-inconsistent behaviour in exchange-rate