The stock price of the US influencer online brokerage firm Robinhood plummeted nearly 7% on Monday. Gary Gensler, chairman of the US Securities and Exchange Commission (SEC), said that the controversial ban on payment for order flow (PFOF) has already been “put on the table.”

Gensler told the media that there was an “inherent conflict of interest” in order flow payments, but did not say whether the SEC discovered situations where the conflict of interest caused investors to lose money. Gensler said staff are reviewing this practice and may make recommendations in the coming months.

Order flow payments are one of Robinhood's biggest revenue streams, meaning the company passes throughSend users' stock, options, and cryptocurrency orders toThe return or compensation that a market maker receives from the execution of high-frequency transactions. While this type of payment is very small, forwarding a large number of orders to a third party for processing can be very profitable. Order flow payments are a controversial practice that has attracted the attention of the Financial Industry Supervisory Authority.

Robinhood has said that if the PFOF model changes, brokers and the industry will be able to adapt.

Prior to Gensler's comments, the SEC said on Friday that the agency was stepping up investigations into the “gamification” and features that encourage trading in online brokerage trading software. These features are being used by online brokers and investment advisors to stimulate retail investors to trade more stocks and other securities and take more risk.

By Monday's close, Robinhood's stock price had plummeted 6.89% to $43.64. The stock rose more than 24% in August.