On 7 May, MaCCI senior member Volker Nocke presented his latest research at the U.S. Department of Justice (Antitrust Division) in Washington, D.C. The paper entitled "An Aggregative Games Approach to Merger Analysis in Multiproduct-Firm Oligopoly" – joint work with MaCCI researcher Nicolas Schutz – makes three contributions. First, it shows that the Herfindahl index, which plays an important role in antitrust practice, provides an adequate measure of the welfare distortions introduced by market power, and that the induced change in the (naively-computed) Herfindahl index is a good approximation for the market power effect of a merger. Second, it provides conditions under which a merger raises consumer surplus, and conditions under which a myopic, consumer-surplus-based merger approval policy is dynamically optimal. Third, it studies the aggregate surplus and external effects of a merger.