RONALD LEE GILMAN, Circuit Judge. This case involves allegations of anticompetitive behavior in the market for burial monuments in the state of Michigan. Three independent monument builders and a nonprofit trade association of monument builders—the Michigan Division of the Monument Builders of North America—(collectively, the Builders) filed the present lawsuit against 20 cemetery operators and the Michigan Cemetery Association (collectively, the Cemeteries). The lawsuit alleges that the Cemeteries are engaged in (1) an illegal tying arrangement, in violation of § 1 of the Sherman Act, (2) an illegal conspiracy to restrain competition and monopolize trade, also in violation of § 1 of the Sherman Act, (3) an illegal conspiracy to restrain trade, in violation of § 2 of the Sherman Act, and (4) violations of the Michigan Prepaid Funeral and Cemetery Sales Act, M.C.L. § 328.225.

The district court dismissed the Builders’ claims after concluding that the proposed geographic market as set forth in the complaint was too narrow as a matter of law. Subsequently, the district court denied motions for sanctions against the Builders that were filed by several of the cemetery operators. For the reasons set forth below, we AFFIRM the judgment of the district court on the merits of the antitrust claims, but VACATE its denial of sanctions and REMAND the case for further proceedings on that issue.