The antitrust laws are intended to permit procompetitive actions by firms and deter anticompetitive actions. We consider firms' incentives to use the antitrust lawsuits for strategic purposes, in particular to prevent procompetitive efficiency-improvement by rival firms. Our main result is that,...

In horizontal mergers, concentration is often measured with the Hirschmann-Herfindahl Index (HHI). This index yields the price-cost margins in Cournot competition. In many modern merger cases, both buyers and sellers have market power, and indeed, the buyers and sellers may be the same set of...