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.
The Forbes Billionaires List, however, said Musk still trails Amazon's Bezos by $US7.8 billion.
Forbes has a more conservative estimate based on the Tesla stake that he has pledged as a collateral for personal loans.
To take that into account, it applies a 25 per cent discount to his shareholding, according to its report in November.
Musk, who co-founded and sold Internet payments company PayPal Holdings Inc, now leads some of the most futuristic companies in the world.
Besides Tesla, he heads rocket company SpaceX and Neuralink, a start-up that is developing ultra-high bandwidth brain-machine interfaces to connect the human brain to computers.
He set up the Boring Company to make affordable tunnels below busy city streets for an all-electric public transportation system to avoid the nasty traffic jams in US cities.
Australian Associated Press