Square ([[SQ]] +7.8%) stock gains as Bitcoin drives up past $43K after Tesla said it invested in the cryptocurrency and will accept Bitcoin for payment on a limited basis soon.Bitcoin has risen about 14% to $43.4K after sliding below $32K in late January.The fintech purchased $50M of the crypto in October; since 2018, the Square Cash app has allowed customers to trade Bitcoin.See how SQ's total return in the past year compares with the PYPL, Bitcoin, and the S&P 500 in chart below.Last October, PayPal ([[PYPL]] +3.6%) introduced its own service for trading Bitcoin, with plans to allow customers to pay for purchases with the digital currency.