A sharp rise in Meta Platforms shares during the September 21 trading session significantly boosted the paper wealth of chief executive Mark Zuckerberg. According to the Bloomberg Billionaires Index, his fortune increased by $25.8 billion in a single day, while Forbes put the one-day gain for the same date at about $25 billion.
The gap reflects different calculation methods, but the driver is the same in both cases: the rise in Meta stock. Most of Zuckerberg’s wealth is tied to his holdings in the company, meaning swings in the share price feed directly into estimates of his net worth.
The report says investor appetite has revived on the back of fresh enthusiasm around artificial intelligence. Meta shares jumped nearly 12% ahead of an AI-focused event, providing the immediate catalyst for the surge in Zuckerberg’s estimated fortune.
On the morning of September 22, Meta shares were trading at $745.69, up 0.60% in the session. The more dramatic move, however, came on Monday, when the rally that drove the wealth headlines took place.
Over broader timeframes, Meta’s performance remains mixed. The stock is up 12.11% over one week, 35.70% over one month, and 13.24% year to date. Even so, it is still down 3.82% over the past year, highlighting how quickly Wall Street sentiment toward the company has shifted. Over five years, the stock has gained 119.31%.
The turnaround follows an uneven period for the company. Business Insider reported on December 4, 2025 that investors had rewarded Meta with a $69 billion boost for cutting metaverse spending. CNBC then reported on July 29, 2026 that the stock fell after disappointing guidance and weakening free cash flow. Now Meta is back in favor as investors again lean into the AI theme.
More broadly, the episode underlines not only the scale of Zuckerberg’s wealth, but also how tightly one individual’s fortune can be linked to a single stock—and how quickly market sentiment can reverse.
