Exxon Corporation (Exxon) and 13 other oil companies (defendants) made up 80 to 90 percent of the oil and petrochemical industry. These defendants shared salary information with each other using various types of surveys and meetings. The salary information was compiled, analyzed, and disseminated by Towers Perrin, a third-party consultant. The defendants then used the information to set salaries for managerial, professional, and technical (MPT) employees. Roberta Todd sued on behalf of a class of Exxon employees (plaintiffs), alleging an unlawful information exchange in violation of § 1 of the Sherman Act, 15 U.S.C. § 1. The plaintiffs argued that the defendants’ information exchange artificially depressed MPT salaries. The district court found that the plaintiffs failed to allege several necessary elements and dismissed the claim. The plaintiffs appealed.