Jack Dorsey’s Square already lets customers buy and sell Bitcoin on its popular Cash App. Soon, it may let them buy and sell stocks.

Square is testing out a new Cash App feature that would enable users to make free stock trades, according to a video outlining the product’s features seen by Bloomberg. While the exact date of its launch is yet to be determined, employees began testing the new feature in recent weeks, according to a person familiar with the company who asked not to be identified discussing private matters.

A spokesman for Square declined to comment.

The free stock trading feature would position Square as a direct competitor to fintech startup Robinhood Markets Inc., which has gained millions of customers by offering no-fee trading, and most recently garnered a valuation of $7.6 billion. Robinhood has since expanded into other offerings such as options trading and margin trading, which would not be offered in Square’s initial product, the person said. Eventually, Square’s new service and others like it could pose a challenge to more established online brokers, like E*Trade Financial Corp.

Square’s Cash App started out by letting users send money to friends, and has since expanded into debit cards and bitcoin trading. While Square doesn’t consistently give updates on how many people are using Cash App, the company said it had more than 15 million monthly active users as of last December. Though there isn’t an immediate path to profitability for most free financial products, the race to add more users to platforms like Cash App has been fierce, with other businesses like PayPal Holdings Inc.’s Venmo also seeing big growth.

Right now, fintech companies offering such products largely make money on the interchange fees when customers use their debit cards or on fees they charge for transferring funds to banks instantly. In its most recent letter to shareholders, Square said that revenue from Cash App was $135 million for the quarter, excluding Bitcoin. In a note published earlier this month, KeyBanc analyst Josh Beck said revenue from Cash App could reach $2 billion over the next three years.