The U.S. Department of Justice (DOJ) has filed an antitrust lawsuit against San Francisco-based Visa Inc., alleging that the company has illegally monopolized the U.S. debit card market. The lawsuit, filed in a federal court in Manhattan, accuses Visa of using exclusionary agreements to hinder the expansion of competing networks and suppressing competition by threatening merchants with high fees and paying off potential rivals. The DOJ also claims that Visa's practices are driving up costs for businesses and consumers. This legal action follows a multi-year investigation into Visa's business practices. Visa's stock has fallen by 5% following the news. Notably, several members of Congress, including Nancy Pelosi, had sold significant amounts of Visa stock in the months leading up to the lawsuit.