Working papers

Innovation Networks and Business-Stealing. (2023). CEPR Discussion Paper DP17911. With Philippe Aghion, Matthew O. Jackson and Antoine Mayerowitz.

Abstract. We use the universe of US Patent and Trademark Office (USPTO) data on patents and inventors from 1976 to 2017 to look at how inventors’ potential concern for business-stealing affects coauthorship on patents. First, we find an inverted-U shape in the fraction of coauthors that an inventor has per year who are new as a function number of other inventors also working in an inventor's field. Second, we find that after a breakthrough invention, an inventor brings in persistently fewer than usual new coauthors. Third, a higher potential concern for business stealing—as measured either by the number of others working or the average price markups by firms in the area—leads to a higher drop in the fraction of new co-authors per patent after a breakthrough. We show how these patterns can be explained via a simple model in which inventors trade off gains from collaboration against threats of business stealing.

Abstract. We find evidence that patent grants influence the stock returns of firms that are connected through technological knowledge dependencies. Using the direction of patent citations between publicly listed companies, we construct a daily exposure of each firm to new patent grants to its knowledge upstream firms (neighborhood) weighted by how intensely they are cited by it. We find that a percent increase in the market value of patents granted to a firm’s neighborhood increases its abnormal returns by about 0.5 basis points each day within three days of patent grant. These spillovers are quantitatively significant, and are about 20 percent in size relative to returns generated a firm's own patents. Moreover, stock returns attributable a firm's neighbors increase over the course the week of grant, whereas they fade out with respect to its own patent grants, suggesting a gradual diffusion of information in financial markets. We further show patents granted to product market rivals decrease, and patents granted to suppliers increase, stock returns of firms. However, accounting for them does not affect our estimates of financial spillovers attributable to technological knowledge dependency. We test for robustness using alternative controls and measures of patenting, restricting analysis to firms operating across industries, using placebo weights for knowledge dependencies, and demonstrating that financial spillovers tend to be localized within a firm's immediate connections.

Foreign competition and R&D specialization. With Antoine Mayerowitz.

Abstract. We examine the impact of the surge in Chinese patenting in the US on the specialization and quality of innovation produced by US firms. Using the rise in Chinese patents filed in the USPTO since the 2000s across various technologies, and leveraging the variation in firms' exposure to these technologies through a shift-share IV design, we demonstrate that the firms most affected by Chinese competition experience an increase in their R&D specialization through a reduction in the number of R&D lines of firms, the scope of patents and the originality of their innovations. We further document that exposure to foreign competition is also associated with a decline in broad measures of patent quality, despite an increase in the number of patents filed by the affected firms. We suggest that these results are consistent with a basic model where firms trade-off research effort on originality with producing more specialized and incremental innovations. Our findings shed light on new potential explanations behind the documented growth in specialization and decline in R&D quality in recent decades.


Innovation Networks and Business-Stealing. (2023). The Economics of Creative Destruction. Ed. Ufuk Akcigit and John van Reenen. Harvard University Press. With Matthew O. Jackson and Antoine Mayerowitz.

Case studies

Analytical Tools in Private Equity: Return Bridge. (2019). Harvard Business School Background Note 220-119. With Victoria Ivashina.

Clayton, Dubilier & Rice at 40. (2018). Harvard Business School Case 819-055. With Josh Lerner and Terrence Shu.

Valuation Techniques in Private Equity: LBO Model. (2018). Harvard Business School Background Note 218-106. With Victoria Ivashina and Alexey Tuzikov.

Works in progress

Perceptions of innovation. With Xavier Jaravel and Josh Lerner.

Heterogeneous technological change.

A century of unequal opportunity in India.

Framing games.