The U.S. stock market’s top regulator is being examined over trading by its own employees.

The Securities and Exchange Commission’s internal watchdog is reviewing whether the agency enforces a ban on employees owning shares that pose conflicts of interest, according to a report to Congress released November 25. The audit by the SEC inspector general follows revelations that officials in the regulator’s New York office invested in securities they’re banned from trading.

SEC employees are restricted from owning shares of most Wall Street banks, which have brokerage and asset-management units that the agency regulates. SEC ethics attorneys said earlier this year they would review internal records to make sure employees are complying with the rule.

The inspector general’s goal is to check the agency’s “efforts to ensure that SEC members and employees comply with the supplemental ethics regulations that prohibit certain securities holdings and restrict trading,” Inspector General Carl W. Hoecker wrote in a semiannual report to Congress.

Researchers at Emory University and Georgia State University found SEC employees have made well-timed trades.

When the employees owned shares of companies under investigation by the SEC, they were more likely to sell than other investors in the months before an enforcement case, according to a paper published in February. The researchers used data on SEC employees’ holdings and trading obtained under the Freedom of Information Act.