research

Unregulated online platforms often host extreme and socially undesirable content. As mainstream platforms tighten moderation, some users shift to unmoderated alternatives, leading to a leakage of extreme content. I develop a duopoly model where an ad-funded mainstream platform competes with an unmoderated fringe. Heterogeneous users choose platforms and create content reflecting their views. The mainstream platform trades off attracting fringe users with making content safer for advertisers. With strong network effects, the socially optimal moderation is more lenient than the profit-maximizing one. Therefore, regulation mandating stricter moderation may backfire by increasing overall content unsafety.

Presented at 2025 TILEC - Economic Governance of Social Media (scheduled), 2025 EARIE, U. Autónoma de Barcelona Workshop (scheduled), 2025 Economics of Digitization Workshop, U. Pablo de Olavide seminar, EU Commision's JRC Workshop, 2024 Jornadas de Economía Industrial, 2024 Spanish Association of Law and Economics Meeting, 2024 ENTER (Brussels)

Sectors occupy different positions in the production network: some are highly central, with strong linkages to other sectors, while others are more peripheral. Yet neither the antitrust literature nor competition authorities have considered whether sectoral centrality affects the impact of mergers. I develop a theoretical model showing that firms in central sectors have weaker incentives to act anticompetitively, as they internalize part of the potential harm due to their ties to the aggregate economy. However, because their effects spread more widely, mergers in central sectors can have larger aggregate consequences. As a result, assessing mergers based solely on consumer surplus in the merging sector may be misleading. Empirically, I show that a one-standard-deviation increase in sector centrality raises the probability that a potential merger is approved by the European Commission by 8 percentage points -- despite centrality never being explicitly mentioned in the case assessments.

Presented at 2025 Spanish Association of Law and Economics Meeting, 2025 Jornadas de Economía Industrial