Robinhood Financial is facing an investigation over CEO Vlad Tenev’s failure to register with the Financial Industry Regulatory Authority, one of Wall Street’s top regulators, the online broker disclosed Tuesday in regulatory filings.

The firm said it received an “investigative request” from FINRA on Monday.

In question is Robinhood’s compliance with “FINRA registration requirements,” particularly the status of Tenev and his co-founder, Baiju Bhatt. FINRA wants documents and information, Robinhood said.

“Robinhood is evaluating this matter and intends to cooperate with the investigation,” the firm said in the documents.

Although it was previously reported that Tenev lacked a FINRA license, the investigation by FINRA is new. It is sure to add scrutiny to Robinhood’s business practices as the popular online stock trading platform prepares to go public. The fintech offers cryptocurrency trading for seven major coins, including fan favorite DOGE.

FINRA requires employees “engaged in the securities business” to register and pass a series of exams that test their “competence” in the securities industry. It's a stopgap meant to “ensure” brokers have a “minimum understanding and expertise,” according to FINRA.

In the past, Robinhood has argued that Tenev is exempt from FINRA registration because he is CEO of Robinhood Markets, the holding company, not its trading subsidiary, Robinhood Financial.

Robinhood declined to comment.