In the 1980s, the market for high fructose corn syrup (HFCS) was highly concentrated, with five HFCS producers (defendants) accounting for 90 percent of sales. The HFCS products were standardized and fungible. In 1988, one producer raised its price, and the other four producers immediately followed. A class of HFCS buyers (plaintiffs) sued, alleging a price-fixing conspiracy in violation of § 1 of the Sherman Act. The parties agreed that the plaintiffs had to show an explicit, not merely tacit, agreement. The plaintiffs presented evidence that the defendants had excess production capacity, yet they still bought HFCS from one another and resold it to customers. Additionally, the defendants’ market share remained stable even as output grew. The plaintiffs presented noneconomic evidence in the form of statements from the defendants suggesting a conspiracy, including references to “an understanding within the industry not to undercut each other’s prices” and to new entrants having to “play by the rules.” The district court held there was not enough evidence for a reasonable jury to find the existence of a price-fixing conspiracy and granted summary judgment to the defendants. The plaintiffs appealed.