Mutual fund giant Fidelity Investments has acquired a 7.4% stake in crypto miner Marathon Digital Holdings for about $20 million, according to a Forbes report. 

• The investment was made on July 22 and was spread across four index-based funds, including Fidelity Extended Market Index Fund (FSMAX), Fidelity Nasdaq Composite Index Fund (FNCFX), Fidelity Total Market Index Fund (FSKAX) and Fidelity Series Total Market Index Fund (FCFMX).
• Fidelity is one of the largest financial services companies in the world, with almost $5 trillion in assets under management and more than 35 million clients.
• The investment reflects the growing institutional and individual interest in investing in crypto-related companies. Several other large institutional firms  have large stakes in Marathon, including Vanguard (7.58%), Susquehanna (2.7%) and BlackRock (1.59%), according to Forbes. 
• Shares of Marathon were up more than 4% on Thursday, potentially on the Fidelity news. Shares of Marathon are up well over 600% over the past year.  
• Marathon said this week it increased its generation of bitcoin by 66% in July.