The U.S. Consumer Financial Protection Bureau sued three of the nation’s largest banks over fraud on Zelle, saying they exploited users’ expectations of security to get them to sign up for the payment platform, without enacting appropriate safeguards.

In a Friday news conference, CFPB Director Rohit Chopra alleged that Bank of America Corp., JPMorgan Chase & Co. and Wells Fargo, as well as Zelle operator Early Warning Services LLC, allowed fraud to flourish on Zelle and “played dumb” when customers reported fraudulent activity on their accounts.