Operational woes aren't the end of Robinhood's challenges. The company has been under regulatory scrutiny for the way it earns revenue -- zero commissions doesn't necessarily mean "free," after all. It uses a model called payment for order flow, selling its customers' orders to market makers who fill them at a marked-up price. The Securities and Exchange Commission fined Robinhood $65 million in 2020 for claiming this practice saved its clients money when it actually cost them $34 million more.