Multiproduct firms and scope adjustment in globalization

A model of heterogeneous firms with variety-specific fixed costs is developed and analyzed to study how multiproduct firms respond to globalization. In contrast with most existing models, the analysis demonstrates that more-productive firms may expand their product scope, which in turn may push up their average costs. A necessary and sufficient condition for scope expansion is that the fixed cost of introducing more varieties increases rapidly with the product scope. With increasing globalization, the percentage of scope-expanding firms diminishes and eventually becomes zero.