Publications

This article compares the approach to antitrust remedies in digital markets in two jurisdictions, the EU and the US. Our study is based the cases against Google, with a particular focus on the problems faced by the European Commission in finding suitable remedies in Google Shopping and Google Android. Our analysis of remedies in the US emphasizes their comparative breadth and distinct purpose, restoring lost competition. We compare the design and objectives of EU and US laws, and explain how these differences impact the abilities of the European Commission and US courts to formulate proper remedies. We find that the European Commission – despite its intensive investigation into the facts - is held back in its ability to impose suitable remedies as a consequence of the design of EU law, as well as the procedures followed in competition law cases. The procedures under the US Sherman Act grant significantly more discretion to the Department of Justice and courts to find proper remedies. We conclude that despite challenges in both jurisdictions, EU and US competition authorities can work symbiotically if the US acts as a second-mover, using lessons from European enforcement to develop suitable remedies. In contrast, we find that on the EU side it will be necessary to amend the relevant laws and procedures to fix their remedy issues.

Sponsored search positions are typically allocated through real-time auctions, where the outcomes depend on advertisers’ quality-adjusted bids—the product of their bids and quality scores. Although quality scoring helps promote ads with higher conversion outcomes, setting these scores for new advertisers in any given market is challenging, leading to the cold-start problem. To address this, platforms incorporate multi-armed bandit algorithms in auctions to balance exploration and exploitation. However, little is known about the optimal exploration strategies in such auction environments. We uti- lize data from a leading Asian mobile app store that places sponsored ads for keywords. The platform employs a Thompson Sampling algorithm within a second-price auction to learn quality scores and allocate a single sponsored position for each keyword. We empirically demonstrate two key ways in which exploration increases platform revenues. First, we quantify how exploration enhances efficiency by discovering high-quality new advertisers, a mechanism well-established in standard bandit problems. Second, un- like standard non-strategic bandit problems, we find that exploration can serve as a tool to increase market thickness, thereby boosting platform revenues. Based on these insights, we propose a customized exploration strategy in which the platform adjusts the level of exploration for each keyword according to specific keyword-level charac- teristics. We derive the Pareto frontier for revenue and efficiency and offer actionable policies that highlight substantial gains for the platform on both fronts when using a customized exploration strategy.

We use the approval of lithium as a maintenance treatment for bipolar disorder (BD) in Denmark in 1976 to investigate the career effects of mental health. Comparing people with and without BD, across cohorts with access to lithium at different ages and relative to people with other mental conditions, we find that access to treatment innovations increases labor market participation by 30 percent and earnings by 26 percent. These benefits operate largely through a reduction in the risk of disability, rather than through changes in occupation or educational achievement. Benefits are larger for people with less parental wealth.

We study whether political polarization shapes US cities' disclosures on climate mitigation (i.e., net zero transition initiatives). Using textual analysis of cities' budgets and annual reports, we categorize these disclosures into two types: (i) tangible descriptions of ongoing projects and (ii) intent, the non-committal discussions of the high-level project purposes and future plans. We find that while there is partisan difference in the ongoing project disclosures, it remains stable over time, suggesting that political polarization doesn't affect the implementation of underlying projects. However, we observe a growing divergence in intent, which is inherently more discretionary as it reflects promises rather than concrete actions. Consistent with cities acting in accordance with the preferences of their stakeholders, we find similar results when we examine the cities' communications with the citizenry and disclosures directed at bondholders.