Compass Lexecon was hired by a third party to assess the competitive effects of the attempted acquisition of Metrobus, a supplier of outdoor advertising in subways and train stations, by JCDecaux, a worldwide leader in outdoor advertising that is particularly strong in Paris and the main French cities, in street advertising and buses. We developed economic analyses of the potential for unilateral and conglomerate effects that were submitted to the French competition authority. Compass Lexecon also opined on the possible delineation of the relevant product market within which to consider outdoor advertising for the purpose ofanalysing the horizontal effects of this transaction. JCDecaux dropped its plans to acquire Metrobus at the end of the Phase II investigation/after the hearing because of the extent of the remedy package it would have had to offer to allay the French competition authority’s concerns, which were aligned with the conclusions of our analyses. The Compass Lexecon team included David Sevy, Valérie Meunier and Anastasia Tseomashko.