Cigarette manufacturing is a concentrated industry dominated by only six firms, including the two parties here. P developed a line of generic cigarettes offered at a list price roughly 30% lower than that of branded cigarettes. By 1984, generics had captured 4% of the market, at the expense of branded cigarettes, and D entered the economy segment, beating P's net price. P responded in kind, precipitating a price war. D's volume discounts to wholesalers were larger. D's rebate structure also encompassed a greater number of volume categories than P's, with the highest categories carrying special rebates for orders of very substantial size. P increased its own wholesale rebates. This precipitated a price war at the wholesale level, in which P five times attempted to beat the rebates offered by D. D always maintained a real advantage over P's prices. P contends that by the end of the rebate war, D was selling its generic products at a loss. This rebate war occurred before D had sold a single generic cigarette. P sued alleging trademark infringement, unfair competition, and eventually an antitrust claim under § 2(a) of the Clayton Act, as amended by the Robinson-Patman Act. P claimed that D's discriminatory volume rebates were integral to a scheme of predatory pricing, in which D reduced its net prices for generic cigarettes below average variable costs. After P's June 1985 increase, list prices on generics did not change again until the summer of 1986, when a pattern of twice yearly increases in tandem with the full-priced branded cigarettes was established. The jury returned a verdict for P. The District Court held that D was entitled to judgment as a matter of law on three separate grounds: lack of injury to competition, lack of antitrust injury to P, and lack of a causal link between the discriminatory rebates and P's alleged injury. P appealed, and the Court of Appeals affirmed. The Supreme Court granted certiorari.