A U.S. watchdog is suing Capital One for allegedly misleading consumers about its offerings for high-interest savings accounts — and “cheating” customers out of more than $2 billion in lost interest payments as a result.

Federal regulators said in a lawsuit on Tuesday that the giant bank deliberately underpaid savings account interest, even as rates rose.

Despite its relatively low interest rate, the CFPB alleged, the 360 Savings account was advertised as a high-interest savings account.