From November 2021 to December 2022 he lost around $US165 billion ($NZ259b), Guinness World Records said in a blog on its website.
BBC reports the figures are based on data from publisher Forbes, but Guinness said other sources suggested Musk's losses could have been higher.
It follows a fall in value of shares in Musk's electric car firm Tesla after he bought Twitter last year.
His $US44b takeover of the social media company has sparked concerns among investors that Musk is no longer giving Tesla enough attention.