Research

This paper studies the welfare effects of patent evergreening, the increasingly prevalent practice of layering secondary patents around a brand drug to extend effective market exclusivity. Using the universe of small-molecule drugs approved from 1995 to 2019, I find that secondary patenting delays generic entry, in a pattern suggestive of strategic incentives, and is negatively associated with investment in primary R&D. A back-of-the-envelope welfare analysis built on a structural demand model suggests that for the patent types that block entry, the loss from deterred generic competition decisively outweighs the gain from the associated quality improvements, and amounts to an average of \$55-\$140 per potential consumer.

This paper analyzes the welfare effects of trade policy in the global commercial aircraft duopoly, focusing on the decades-long dispute between the European Union and the United States over Airbus and Boeing. We develop a structural model of demand and supply with endogenous product entry and use it to simulate the two principal policy instruments: subsidies and tariffs. The simulations show that nominally symmetric policies can generate markedly asymmetric firm-level outcomes because their effects depend on firms' underlying costs, product portfolios, and market positions. Endogenous product entry is the primary adjustment margin and accounts for most of the resulting profit and welfare effects.