Antitrust law has three main targets—collusion, mergers, and monopolization. The first two are relatively uncontroversial targets. While facts and theories in specific cases may be disputed, the overall rationales for these doctrines are widely accepted. Monopolization law, originating in Section 2 of the 1890 Sherman Act, is notoriously different. Unlike other branches of antitrust, which target decisions by firms not to compete with each other, monopolization is portrayed as a dominant firm protecting itself by harming nascent rivals. Since competition—offering more and better products at lower prices—also harms rivals, antitrust observers fall into two warring camps. Skeptics argue that because monopolization is likely to be confused with competition that could benefit consumers, Section 2 cases should bear very high burdens of proof. Activists, on the other hand, believe that one can protect competition by protecting some competitors against the actions of another. The focus on protecting rivals has also led to legal requirements that make little economic sense. One, prior dominance, paradoxically asserts that one cannot monopolize without already having a monopoly. This conflates the nature of the offender with the nature of the offense and undercuts claims that alleged abuses have competitive relevance. Another, profit sacrifice, states that practices cannot be anticompetitive unless they cause the perpetrator short-run losses. This requirement, confusing intent with effect, is neither necessary nor sufficient for economic harm. No one would argue that mergers or collusion should be stopped only if those undertaking them were losing money. We could avoid spurious requirements and limit controversy by recasting monopolization law to make it more like collusion and merger law. This entails focus not on rivals but on monopolization of otherwise competitive complementary markets, e.g., in production inputs, distribution channels, or retail outlets. Complementary market monopolization (CMM) is necessary and sufficient for anticompetitive harm. This focus would allow courts to eliminate dubious requirements and adopt widely accepted tools from other areas of antitrust, e.g., merger guidelines. CMM provides a way to assess exclusionary tactics such as bundled discounts and predatory pricing, bringing to light important and neglected differences between cases regarding direct harms and those based on indirect strategic effects. Moving to CMM could be effected by deleting “or maintain” from the “create or maintain a monopoly” definition of monopolization in Section 2 law.