According to Decrypt, documents submitted by Vanguard Group, the world's second largest fund management company, to the U.S. Securities and Exchange Commission (SEC) show that its current holdings of Bitcoin mining company stocks have increased to approximately US$560 million, including a 60% increase in Marathon Digital MARA shares, from 10.9 million shares to 17.5 million shares (approximately US$280.5 million); and an 18% increase in Riot Blockchain shares, from 15.2 million shares to 17.9 million shares (approximately US$281 million).