Mark Zuckerberg’s wealth dropped as much as US$31 billion, among the biggest one-day drops in wealth ever, after Meta Platforms Inc.’s fourth-quarter results fell short of analysts’ expectations.

Meta is in the midst of a historic stock collapse after its earnings on Wednesday showed no growth in monthly Facebook users last quarter relative to the prior period, raising concerns about the company’s future growth. Shares tumbled 24 per cent at 10:25 a.m. in New York Thursday.

Meta’s steep decline leaves Zuckerberg, the company’s chief executive officer, with a net worth of about US$92 billion, down from US$120.6 billion as of market close on Wednesday, according to the Bloomberg Billionaires Index. It’s enough to push the 37-year-old outside the list of the Top 10 wealthiest people in the world for the first time since July 2015.

A one-day wealth loss of US$31 billion would rank as the second-biggest ever caused by a share-price decline, only rivaled by the volatile swings in Elon Musk’s fortune. The world’s richest person lost US$35 billion in a day in November as Tesla Inc. shares fell following a Twitter poll in which Musk asked voters if he should sell 10 per cent of his stake in the company. His net worth also plunged US$25.8 billion last week.

Meta’s co-founders are also facing unprecedented declines in their personal fortunes. Dustin Moskovitz, the world’s 79th-richest person with a net worth of US$21.2 billion as of Wednesday, has lost about US$3 billion, while Eduardo Saverin, worth US$17.5 billion, is down more than US$4 billion. 

The US$2.5 billion personal fortune of Sheryl Sandberg, Meta’s chief operating officer, fell by more than US$100 million, according to data compiled by Bloomberg. Compared with Zuckerberg, however, Sandberg’s wealth is less concentrated in the company’s shares, softening the blow.

For Meta, the disappointing earnings add to its challenges. It’s in the middle of a number of regulatory fights and also looking to justify its strategic shift to bet on an immersive internet known as the metaverse. Meanwhile, other platforms like TikTok and YouTube are gaining ground with younger users.