Empirical work has drawn attention to the high degree of productivity differences within industries and their role in resource allocation. This paper examines the allocational efficiency of such markets. Productivity differences introduce two new margins of potential inefficiency: selection of the right distribution of firms and allocation of the right quantities across firms. We show that these considerations affect welfare and policy analysis, and market power across firms leads to distortions in resource allocation. Demand-side elasticities determine how resources are misallocated and when increased competition from market expansion provides welfare gains.

Resource-based theories propose that firms grow by diversifying into products that use common capabilities. We provide evidence for common-input capabilities, using a policy that removed entry barriers in input markets to show that the similarity of a firm’s and an industry’s input mix determines firm production choices. We model industry choice and economies of scope from input capabilities. When the model is estimated for Indian manufacturing, input complementarities make firms 5% more likely to produce in an industry and are quantitatively as important as time-invariant drivers of coproduction rates. Upstream entry barriers were equivalent to a 9.5% tariff on inputs.