Capital One is accused of defrauding customers out of $2 billion

Capital One’s ad had many of the same promises other banks offer for high-yield savings accounts: There were no fees, no minimum deposits, and the money would earn much more in interest than traditional bank accounts.

“What’s the catch? There is none,” boasted the bank.

But according to a lawsuit filed against Capital One on Tuesday by the Consumer Financial Protection Bureau, there was one, and it cost depositors more than $2 billion.

For years, Capital One kept interest on the high-yield product artificially low at 0.30 percent annually last summer, for example, even as the Federal Reserve raised rates above 5 percent.

Banks are generally allowed to pay as little interest as their customers will allow, but Capital One, according to the lawsuit, went too far by deliberately confusing its customers about its products. The bank operated two separate, nearly identically named account options—360 Savings and 360 Performance Savings—and prohibited its employees from volunteering information about or marketing 360 Performance Savings, the higher-paying one, to existing customers.

In its lawsuit, the consumer agency called the practice misleading, abusive and illegal. “The only thing that has ever distinguished 360 Performance Savings from 360 Savings is the former product’s higher interest rate,” the lawsuit states.

A spokesman for Capital One, Sie Soheili, declined to comment on the specific allegations in the suit, but he said the bank, the nation’s ninth largest, disagreed with the claims and would contest them in court. The bank is trying to complete a deal to acquire credit card issuer Discover.

The lawsuit is the latest in a flurry of last-minute admonitions from the consumer agency before the inauguration of President-elect Donald J. Trump. Republicans deeply loathe the agency, which was founded in 2011 and which they have said is an example of bureaucratic overreach, although Mr. Trump kept it alive in his first term.

Almost every business day in the past month, the agency has filed a lawsuit or proposed rule change or other pending case against a major financial institution. The lawsuit Tuesday was not the agency’s first in recent weeks involving Capital One; last month, the regulator accused Zelle, the money transfer app owned by the bank, of failing to protect its customers from more than $800 million in fraud.

Mr. Soheili said in a statement that regulators continued their “recent pattern of filing 11th-hour lawsuits prior to a change in administration.”

A spokeswoman for the consumer agency, Tia Elbaum, responded: “Where we see violations of the law, we will take action.”