• Working Papers

“Asymmetric Price Competition on Hybrid Platforms: Theory and Evidence from Amazon", joint with Luise Eisfeld and Li Yu,  August 2026

Many e-commerce platforms operate in hybrid mode: they host third-party sellers, earning ad-valorem commissions, while also retailing directly. In an oligopoly model, this creates two platform-specific incentives – a revenue-sharing effect and a commission-saving effect – implying that platform retail presence can exert weaker competitive pressure than third-party entry, and that common cost shocks are passed through asymmetrically across seller types. Using data from Amazon’s U.S. marketplace and repeated within-product availability changes, we find that third-party prices respond modestly more to third-party entry and exit than to Amazon’s. Consistent with the model, we estimate that commodity cost shocks are fully passed on to final prices by third-party sellers, whereas pass-through is significantly lower in the case of Amazon. 

"Mandating Interoperability in Messaging App Markets", joint with Mudit Dhakar

This paper investigates how mandated interoperability affects market contestability and consumer welfare in messaging app markets where consumers can multi-home.   We develop  a  simple model of direct network effects with two vertically differentiated apps: a free incumbent app with a large installed base, and a paid niche app lacking an installed base but offering superior intrinsic quality. We show that the paid niche app faces a strategic choice between two pricing regimes: a Mass Strategy, which leverages network effects to reach a broader user base, and a Niche Strategy, which relies on its superior intrinsic quality to appeal only to high-value users. By reducing the proprietary network effects generated by single-homing users, an intermediate level of interoperability can hurt the niche app when the incumbent’s installed-base advantage is modest. Our findings highlight a regulatory trade-off: enhancing contestability requires either sufficiently low or sufficiently high interoperability, yet a low level of interoperability may, in some cases, reduce consumer welfare.

"Data, Targeted Advertising and the Quality of Journalism: The Case of Accelerated Mobile Page (AMP)",  joint with Doh-Shin Jeon

This paper studies how newspapers’ adoption of Google’s Accelerated Mobile Page (AMP), a publishing format for mobile devices enabling instant loading of web pages, changes data allocation and thereby newspapers’ incentive to invest in the quality of journalism when consumer data is used for targeted advertising. The adoption of AMP allows Google to obtain consumer data from AMP articles and to combine it with other sources of consumer data to improve the targeting of the advertisements served by Google on other websites. Even if such data combination increases static efficiency, it can reduce dynamic efficiency when it lowers the ad revenue per newspaper traffic and thereby reduces the quality of journalism. Newspapers face a collective action problem as a newspaper’s adoption of AMP generates negative externalities to other newspapers through data leakage. In addition to leveraging its search monopoly power, Google can use a divide-and-conquer strategy to induce newspapers to adopt AMP. We provide policy remedies.

"Vertical Integration and Foreclosure in Two-Sided Markets"

This paper studies vertical foreclosure issue in platforms characterized by bilateral cross-group network externalities. I focus on an environment where the monopolistic platform and downstream sellers face uncertainty over the gains from trade at the contracting stage. As the random shock is non-contractible, contracting creates friction which distorts the platform’s pricing structure. By contrast, vertical integration mitigates this problem by allowing the platform to incorporate the random shock in consumer pricing. Due to the interaction between transaction friction and cross-group network externalities, I find that vertical integration could reduce the platform’s incentive of foreclosure.

• Work-in-Progress

Digital Copyright: Search Engine’s Use of Snippets