Jack Dorsey's Square is reportedly testing a free stock-trading service that would rival Robinhood

Jack Dorsey is squaring up to Robinhood with a free stock-trading service.

The Twitter CEO's fintech company, Square, is testing free buying and selling of stocks on its Cash App, according to Bloomberg.

Adding the feature would make Cash App a direct rival to Robinhood, the no-fee trading platform valued at $7.6 billion in July.

Watch Square trade live.

Jack Dorsey is squaring up to Robinhood with a free stock-trading service.

The Twitter CEO's fintech company, Square, is testing free buying and selling of stocks on its Cash App, Bloomberg reported, after viewing a promotional video of the new feature.

Adding the feature would make Cash App a direct rival to Robinhood, the no-fee online trading service valued at $7.6 billion in July. Robinhood counts venture capital firm Sequoia Capital among its investors.

Square's Cash App offers digital money transfers, debit cards, and bitcoin trading. It more than doubled its monthly active users to 15 million in 2018. Square will be looking to emulate its bitcoin success: revenue from the cryptocurrency soared 168% year-on-year in the first half of this year, helping to drive total sales up 44% to $2.1 billion.

Square hasn't settled on a launch date for stock trading, Bloomberg said, citing a person familiar with the company.