Trading platform Robinhood could lose a significant revenue source should the United States Securities and Exchange Commission move to ban the controversial payment for order flows (PFOF) — routing retail trading orders to market makers.

Brokers like Robinhood often use the practice to offset trading fees, thus providing zero commission trading to its retail customer base.

According to the Wall Street Journal on Wednesday, Robinhood’s initial public offering filing revealed that the broker earned 81% of its Q1 revenue from payment for order flows covering stock, options and crypto. As previously reported by Cointelegraph, Robinhood filed for its IPO on Thursday.

SEC Commissioner Gary Gensler has previously criticized the practice, and the GameStop saga from earlier in the year has also put the matter in the spotlight. Indeed, the company paid a $65million fine imposed by the SEC back in December amid allegations that Robinhood misled retail customers about the use of PFOF.

Meanwhile, Robinhood has stated that any SEC action against PFOF, including stringent regulations or an outright ban, could negatively impact its business. Payment for order flow is a banned practice in jurisdictions such as Canada and the United Kingdom.

The uncertainty over the SEC’s stance on PFOF under Gensler is the latest hurdle for Robinhood in its IPO journey. Back in June, the SEC’s inquiry into the company’s crypto trading business reportedly delayed its IPO filing.

Related: Facing $70M in fines from regulators, Robinhood files for IPO

Indeed, Robinhood’s crypto division has experienced significant growth in 2021 with its Q1 performance constituting a sixfold increase over the previous quarter. Back in April, the company announced a new chief operating officer to oversee its expanding cryptocurrency trading operations.

As previously reported by Cointelegraph, the U.S. Financial Industry Regulatory Authority fined Robinhood $70 million back in June. The FINRA fine was reportedly due to “widespread and significant harm” attributed to the company against thousands of its users.