Square has invested $50 million - about one per cent of its total assets - in bitcoin, arguing that the cryptocurrency is an "instrument of economic empowerment".
The payments firm says it has bought 4709 bitcoins, which are currently trading at nearly $11,000, up from just over $7000 in January.
Square launched bitcoin trading in 2018 through its Cash App. Last year it formed Square Crypto to focus on contributing to bitcoin open-source work.
Jack Dorsey, the company's founder, has long been a crypto champion, predicting in 2018 that bitcoin would one day become the world's "single currency".
Square's decision to link its investment to economic empowerment chimes with Dorsey's recent spat with Brian Armstrong, the boss of crypto exchange Coinbase.
After Armstrong said that Coinbase would keep out of politics and societal issues, Dorsey responded that crypto "is direct activism against an unverifiable and exclusionary financial system which negatively affects so much of our society".