Do Prices Determine Vertical Integration?*

What is the relationship between product prices and vertical integration? While the literature has focused on how integration affects prices, this paper provides evidence that prices can affect integration. Many theories in organizational economics and industrial organization posit that integration, while costly, increases productivity. It follows from firms’ maximizing behavior that higher prices induce more integration. The reason is that at low prices, increases in revenue resulting from enhanced productivity are too small to justify the cost, whereas at high prices the revenue benefit exceeds the cost. Trade policy provides a source of exogenous price variation to assess the validity of this prediction: higher tariffs should lead to higher prices and therefore to more integration. We construct firmlevel indices of vertical integration for a large set of countries and industries and exploit cross-section and time-series variation in import tariffs to examine their impact on firm boundaries. Our empirical results provide strong support for the view that output prices are a key determinant of vertical integration.