Now that the economic recovery is well underway, there are renewed concerns that the financial sector is back to engaging in some of the same problematic activities that played a role in sparking the Great Recession. For one thing, sub-prime mortgage loans are back, and “too big to fail” banks remain huge.

One organization that’s supposed to be keeping an eye on financiers is the Financial Industry Regulatory Authority, or FINRA—an independent nonprofit that was established in the merger of National Association of Securities Dealers and the regulatory arm of the New York Stock Exchange in 2007. But some have doubts that FINRA is doing its job.

At a senate hearing on Thursday, Senator Elizabeth Warren grilled FINRA’s chairman, Richard Ketchum, about how his agency deals with misconduct among advisors—in other words, when financial advisors violates investment rules or commits fraud. While the hearing was called to discuss regulatory reforms and whether American stock markets have become too complex, Warren took the opportunity to question whether the financial industry was being properly regulated. “As the head of FINRA,” Warren asked Ketchum, “what are you going to do to make sure that the elderly and the people who can least afford bad financial advice don’t fall into the net of someone who’s already got a documented history of misconduct?”

Warren’s questions were pointed, but for good reason: During the hearing she brought up a new study, from the University of Chicago’s Booth School of Business and the University of Minnesota, that found misconduct to be alarmingly frequent among financial advisors. The study, which used FINRA’s database to look at disclosures indicative of fraud and wrongdoing at nearly 4,000 securities firms, is the first large-scale evaluation of the industry’s behavior. It looked at the records of 1.2 million financial advisors working between 2005 and 2015, and found that one in 13 were flagged for misconduct. More worryingly, although half of those advisors were fired as a result, 44 percent were reemployed within a year.

The study also found that misconduct was concentrated among firms with certain types of customers: “Our results suggest that misconduct is widespread in regions with relatively high incomes, low education, and elderly populations. These results suggest that firms that specialize in misconduct with several unscrupulous financial advisors are likely targeting vulnerable consumers, while other firms use their reputation to attract sophisticated consumers,” the study’s authors wrote.

The study Warren cited also compiled a list of firms where misconduct was highest. Topping the list was Oppenheimer & Co. where nearly 20 percent of advisors have misconduct records, followed by First Allied Securities and Wells Fargo Advisors. Firms with the lowest misconduct rates were Morgan Stanley and Goldman Sachs—where less than 1 percent of advisors had been disciplined for misconduct.

Ketchum, who is retiring later this year, told Warren he agreed that the study’s results were “dismaying,” and that it’s curious that firms continue to hire people with such records of misconduct. That said, he pointed to the fact that FINRA suspends and bars roughly 1,000 people a year for misconduct and keeps tabs on high-risk advisors, but Warren seemed unsatisfied with his answer. Near the end of her questioning, she pressed Ketchum on what FINRA plans to do beyond its current efforts: “You obviously are not getting them out of the industry. They’re still there, and they’re there in big numbers, and they’re concentrated in places where they are most likely to encounter unsophisticated consumers. And I think that’s a real problem we’ve got.”