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