The 51-year-old entrepreneur recorded an unprecedented $US200 billion ($A294 billion) loss in wealth since November 2021, according to the Bloomberg Billionaires Index.
Musk was reportedly worth $US340 billion 14 months ago.
He is now valued at $US137b, which also cost him the distinction of being the world's wealthiest man.
That title now belongs to French lifestyle brand chairman Bernard Arnault, who's worth $US162b ($A238b).
Forbes dropped Musk from the top-spot in its billionaire rankings in December.
Musk, who operates the electric car company Tesla and aeronautics business SpaceX, acquired the social media platform Twitter for $US44b in October following a prolonged flirtation dating back to April.
It coincided with an ongoing depreciation in Tesla stock value that some shareholders do not believe is coincidental.
Musk joked about losing money on Twitter on the social media platform in November.
"How do you make a small fortune in social media?" he tweeted. "Start out with a large one."
The billionaire businessman has used the platform to advance his politics, which has made him largely unpopular with progressives who tend to be supportive of businesses like Tesla that promote alternative energy.
Tesla recorded a 65 per cent drop in stock value in 2022, capped off by a 44 per cent plummet in December. Even Musk has sold billions of dollars in shares of the company as he continues efforts to make Twitter profitable.
Amazon founder Jeff Bezos became the first person to become worth more than $US200b in April 2021.
Bloomberg puts his current worth at $US107b ($A157b). Musk is the only other person to have reached the $US200b plateau.
He welcomed the new year Sunday on Twitter.
"One thing's for sure," Musk predicted. "It won't be boring."
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