S&P Global Ratings, the American credit rating agency, has granted a rating to Michael Saylor's Bitcoin (BTC) proxy Strategy (Nasdaq: MSTR). Related: What is Bitcoin mining? Explained Led by co-founder and executive chairman Michael Saylor, Strategy is the world's leading Bitcoin treasury firm. It now holds 640,808 BTC, worth approximately $74 billion, on its balance sheet. The company raises funds to acquire Bitcoin by selling a common stock, MSTR, and preferred stocks, STRF, STRK, and STRD. Thomas Lee ...