The legality of a horizontal merger under section 7 of the Clayton Act turns on a reckoning of its social costs and benefits. This paper reviews what economics has to say about that reckoning and explores the relationship between economic learning and merger law and policy

We introduce knowledge spillovers in a model of innovation competition à la Federico et al. (2017) and Denicolò and Polo (2018), which otherwise features horizontal mergers that harm innovation due to the business stealing effect. With knowledge spillovers, competition discourages investment...