Sens. Elizabeth Warren, D-Mass, and Tom Cotton, R-Ark., accused Finra Wednesday of exposing investors to “real risk” through lax oversight of broker-dealers.

“Each day that Finra fails to take stronger action is another day that working families will be exposed to an unacceptably high risk of misconduct,” the senators charged in a letter to Finra Chairman and CEO Richard Ketchum.

They asked for a comment from Ketchum by June 15.

The letter essentially repeats allegations National Bureau of Economic Research scholars made in February that Finra was allowing many broker-dealers with a history of criminal and federal and state securities regulatory infractions to remain in the industry.

The patterns of conduct cited in the study are concerning, Warren and Cotton wrote. They asked the FINRA chief to detail what steps the agency is taking to address high levels of misconduct and recidivism in the brokerage industry and to tackle the problem of firms with a large share of employees with a history of misconduct-disclosures on BrokerCheck.

A Finra spokesperson said the self-regulatory organization is considering the issues raised in the letter.

“We’ve received the senators’ letter, share their concerns about these issues and are pursuing measures to address them," the spokesperson said. "Finra looks forward to working with them on these and other important investor protection issues.”