Examining a standard monopolistic competition model with unspecified utility/cost functions, we find necessary and sufficient conditions on their elasticities for welfare losses to arise from trade or market expansion. Two numerical examples explain the losses (under unrealistic elasticities).

Price dispersion of US imports are investigated across US districts of entry. Markups explain about 31% of price dispersion, while marginal costs of production explain about 69%; effects of trade costs, for which we have actual data, are almost none.

We develop a two-factor, two-sector trade model of monopolistic competition with variable elasticity of substitution. Firms' profits and sizes may increase or decrease with market integration depending on the degree of asymmetry between countries. The country in which capital is relatively...