The wealth of 643 of US' richest billionaires rose from $2.95 trillion to $3.8 trillion between March 18 and September 15. This marks a 29% increase over those six months. That's according to a report by the Institute for Policy Studies and Americans for Tax Fairness said. Tesla founder Elon Musk's wealth increased by 273% in the period to $92 billion. Jeff Bezos wealth increased 64.8%, from $113 billion to $182. Mark Zuckerberg's wealth increased from $54 billion to $100.