Un sistema disperso de mercados concentrados: Propiedad común y oligopolios regionales en el transporte público de Costa Rica[A Dispersed System of Concentrated Markets: Common Ownership and Regional Oligopolies in Costa Rica's Public Bus Transport]

Bus routes in Costa Rica are concessions that the State grants to private operators. This article measures how concentrated their control is when ownership is traced back to the ultimate owners. Using the 2018 shareholder certifications and the kinship network among shareholders, a cascading matrix model assigns the 383 routes to concessionaire companies, to legal owners and to economic units that group each family. Once families are consolidated, the equivalent number of agents falls from 155 companies to 103 units, and common ownership, measured with the modified Herfindahl-Hirschman index, leaves 72 independent decision centers. At the national level, no index comes close to the oligopoly thresholds. In four of the six planning regions, however, the four largest agents control between 50\,\% and 59\,\% of the routes, and almost four in five cantonal markets exceed the tight-oligopoly threshold; with routes weighted by passengers, five regions are oligopolistic. Agent size follows a lognormal distribution plus a cluster of single-route owner-operators, the same in every region, and the number of agents in each region is enough to reproduce its concentration. The per-person limit in Article 11 of Law 3503 is almost always met, yet half of the routes belong to concessionaires that share an owner with another concessionaire. The results suggest that regulators should look at the economic group as a whole when they grant and renew concessions.