Tesla Inc chief and billionaire entrepreneur Elon Musk has surpassed Amazon.com Inc's top boss Jeff Bezos to become the world's richest man, Bloomberg News says.
Including Thursday's gains in Tesla shares, Musk, 49, had a net worth of more than $US188.5 billion ($A243.6 billion), $US1.5 billion more than Bezos, the report said.
Musk's personal wealth has been boosted by last year's more than eight-fold surge in the shares of Tesla, which became the world's most valuable car maker.
He has a 20 per cent stake in the car maker and about $US42 billion of unrealised paper gains on vested stock options, according to the Bloomberg report.
Tesla shares were up as much as 7.4 per cent on Thursday at a record high of $US811.61.