BlackRock Capital Management recently invested in two U.S. bitcoin mining companies, Digital Marathon and Rayot Blockchain. BlackRock's documents for the U.S. Stock Exchange Commission show the company bought 6.71 percent of digital marathon shares and 6.61 percent of Raiot Blockchain's shares. The investment came at a time when bitcoin miners' earnings have increased to $44 million per day. It should be noted that Block Rock with 9 trillion assets under management is the largest capital management company in the world