Seminar The macroeconomic effects of mergers and acquisitions in the United States Add to calendar 2026-01-20 11:00 2026-01-20 12:15 Europe/Rome The macroeconomic effects of mergers and acquisitions in the United States Conference Room Villa La Fonte YYYY-MM-DD Print Share: Share on Facebook Share on BlueSky Share on X Share on LinkedIn Send by email Scheduled dates Jan 20 2026 11:00 - 12:15 CET Conference Room, Villa La Fonte Organised by Department of Economics This event features a discussion with PhD Candidate Brian Cabaco (University College London). I study the macroeconomic impact of merger waves in the United States since 1980 and document these have generated substantial economic losses. Using firm-level event studies, I provide new evidence that merger announcements generate positive abnormal returns for acquirers and their competitors, but not the targets' competitors, patterns inconsistent with industry signaling channels and instead suggesting anticompetitive effects. I aggregate the estimated abnormal returns to construct a novel proxy for merger activity and show consolidation waves predict persistent declines in GDP and labor productivity alongside rising prices. To rationalise these findings, I develop a firm dynamics model with an auction-based market for mergers and variable markups that successfully replicates merger matching patterns, firm sales concentration, and the markup distribution. The model reveals mergers lead to large welfare losses through worsened allocative efficiency from higher markups and reduced firm entry.