Mark Zuckerberg’s fortune grew by an estimated $25 billion in a single trading day after Meta shares jumped nearly 12 percent on September 22, 2026.

The rally was driven by investor excitement over Meta’s artificial intelligence ambitions ahead of its annual Meta Connect conference, and by Wells Fargo raising its price target on the stock to $796 from $640. The bank pointed to user adoption of Muse, Meta’s new AI assistant.

Forbes estimated Zuckerberg’s net worth at about $253.6 billion after the surge, placing him sixth on its real-time billionaires list. The one-day gain ranked among the largest ever recorded for an individual billionaire.

The gains were paper wealth, tied to his roughly 13 percent stake in Meta, and can swing with each trading session. Days later, a Goldman Sachs downgrade wiped billions off again, a reminder of how quickly market moods change.

The swing shows how concentrated founder wealth moves with a single trading day. Zuckerberg’s Meta stake accounts for almost all of his net worth, so a 12 percent share move translates into tens of billions on paper. He has pledged to give away most of his wealth through the Chan Zuckerberg Initiative.