With bitcoin ([[BTC-USD]]) back in a bull market after early 2021 jitters, CFRA notes investors are now wondering what other equities have exposure to the cryptocurrency - and a zoom-in on payments companies suggests positive implications for its players. Square (SQ), for example, allows users to buy and sell bitcoin, and users of its popular peer-to-peer money app Cash App can also swipe over and buy bitcoin. "So, how much bitcoin has its users bought? A lot" - about $4.6B last year, nearly a ninefold increase in sales from 2019.Square makes very little profit on selling bitcoin, about 2% per dollar of bitcoin sold. That meant just an incremental $97M in gross profit. And while Square's bitcoin profits pale in comparison to its other services, it could be a meaningful driver in the future, CFRA says. Assuming a case where bitcoin sales double every year for the next five, and