While the labor market implications of mergers have been historically ignored as "out of market" effects, recent actions by the Department of Justice (DOJ) place buyer market power (i.e., monopsony) at the forefront of antitrust policy. We develop a theory of multi-plant ownership and monopsony...

We contribute a theory in which three channels interact to determine the degree of monopsony power and therefore the wedge between a worker's spot wage and her marginal product (henceforth, the wage markdown): (1) heterogeneity in worker-firm-specific preferences (nonwage amenities), (2) firm...