Net worth of the billionaires opposing California's wealth tax: Elon Musk: $844 billion Larry Page: $262 billion Sergey Brin: $243 billion Mark Zuckerberg: $228 billion Larry Ellison: $209 billion Yes. We must tax billionaires. And it starts in California. | Bernie Sanders

Elon Musk becomes the first person ever to top the $800 billion mark in net worth. CNBC's Robert Frank has the details. Watch more: cnb.cx/3ZTlz9L | CNBC

Tesla billionaire Elon Musk is officially buying Twitter. Musk is the world’s richest person with a net worth of $268.2 billion (that’s over $96 billion more than Jeff Bezos who is ranked 2nd). Twitter’s board has decided to sell the company, accepting Tesla billionaire Elon Musk’s offer of $54.20 per share in cash, which values the company at around $44 billion. Shares of Twitter added to recent gains and jumped more than 5% on Monday after the social media company formally accepted the buyout