In an SEC regulatory filing, the payments giant says that last month it received a civil investigative demand from the DoJ seeking documents and information regarding a potential violation of the Sherman Act, a competition law."The CID focuses on Mastercard’s US debit program and competition with other payment networks and technologies," says the filing.In 2021, the DoJ began a similar investigation into Visa and whether the company had restricted the ability of merchants to send debit transactions through less expensive networks.According to Bloomberg, in January the justice department issued more CIDs to Visa seeking additional documents and information.Mastercard CFO Sachin Mehra tells Bloomberg: "It’s not surprising that the DOJ would request information from other players in the debit space."