The combined net worth of Elon Musk and Jeff Bezos has approached $500 billion on 27th October, fueled by the unrelenting rally in Tesla Inc. shares and a broad surge in tech stocks. The value of the two fortunes — a sum bigger than the market value of Johnson & Johnson and about equal to that of America’s biggest bank, JPMorgan Chase — is yet another watershed moment in what’s shaping up to be a historic week for billionaires. Musk, co-founder of publicly traded Tesla and closely held rocket company SpaceX, has added $122.3 billion to his fortune this year, pushing his net worth to $292 billion. Amazon.com Inc. founder Bezos is worth $196.3 billion. Musk’s wealth has ballooned partly because he hasn’t sold any of his Tesla stock for years, instead tapping banks for loans using his stake in the electric-vehicle maker as collateral. The 10 richest Americans, including Bill Gates and Mark Zuckerberg, are worth a total of $1.4 trillion.