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 carmaker.
He has a 20 per cent stake in the carmaker and about $42 billion of 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 $811.61.
Shares in the electric car company soared on hopes that a Democrat-controlled US Senate would usher in a new green agenda.
The Forbes Billionaires List, however, said Musk still trails Amazon’s Bezos by $7.8 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, now leads some of the most futuristic companies in the world.
Besides Tesla, he heads rocket firm SpaceX and Neuralink, a startup that is developing ultra-high bandwidth brain-machine interfaces to connect our brains to computers.