International Trade and Macroeconomic Dynamics with Heterogeneous Firms

We develop a stochastic, general equilibrium, two-country model of trade and
macroeconomic dynamics. Productivity differs across individual, monopolistically
competitive firms in each country. Firms face a sunk entry cost in the domestic
market and both fixed and per-unit export costs. Only relatively more productive
firms export. Exogenous shocks to aggregate productivity and entry or trade costs
induce firms to enter and exit both their domestic and export markets, thus
altering the composition of consumption baskets across countries over time. In a
world of flexible prices, our model generates endogenously persistent deviations
from PPP that would not exist absent our microeconomic structure with heterogeneous
firms. It provides an endogenous, microfounded explanation for a Harrod-
Balassa-Samuelson effect in response to aggregate productivity differentials and
deregulation. Finally, the model successfully matches several moments of U. S.
and international business cycles.