Plaintiffs’ attorneys have filed multiple antitrust class actions against Visa Inc. following the Sept. 24 U.S. Department of Justice complaint alleging the global payments company maintains an unlawful monopoly in U.S. debit card network services markets.

At least four class actions filed in New York or California federal courts since Oct. 1 allege Visa has forced merchants and consumers to pay artificially inflated prices for debit card transactions. All of these lawsuits demand treble or triple damages and an injunction that would end Visa’s alleged anticompetitive practices.