Mastercard Loses $18.6 Billion Class Action Court Ruling (2)

Mastercard Inc. faces the prospect of a 14 billion-pound ($18.6 billion) U.K. class action -- the largest of its kind -- after losing another battle at the country’s highest court over illegal swipe fees.

The Supreme Court ruled in favor of a group behind a proposed British suit, representing some 46 million consumers. Friday’s decision also sets the stage for a slew of class-action cases, after the judges made it easier to bring mass claims.

Mastercard has faced numerous legal challenges since European Union courts said its payment fees unfairly restricted competition. The decision means the long-running British case, which ...