Meta CEO Mark Zuckerberg has vaulted past Dell Technologies Chairman and CEO Michael Dell to become the world’s fourth-richest person, powered by the breakout performance of Meta’s AI assistant Muse. As of the U.S. market close on September 24, Zuckerberg’s net worth was estimated at $266.4 billion.
According to Forbes, Meta shares rose 4.5% that day to close at $777.59, a 2026 closing high. The core catalyst was Muse, Meta’s autonomous AI assistant launched earlier this month—capable of booking travel, sending emails, and managing connected home devices. Zuckerberg has positioned Muse as a critical step toward delivering “personal superintelligence” across Meta’s platforms.
Muse officially launched on September 8, and market reception has far exceeded expectations. Data from market analytics firm Sensor Tower shows that within just five days of release, Muse surpassed OpenAI’s ChatGPT in downloads to become the most-downloaded free app on the U.S. iOS platform. As of Monday local time, cumulative downloads since launch had topped 2.5 million. Zuckerberg’s personal fortune jumped by $25 billion in a single day on September 21 alone.
Rapid reshuffling of the billionaire rankings
Zuckerberg’s ascent up the wealth rankings has been remarkably swift. On September 23, he had just overtaken Google co-founder Sergey Brin to reach fifth place globally; a mere day later, he leapfrogged Dell to claim the No. 4 spot.
Dell’s fortune, by contrast, has been shrinking. On September 24, Dell’s net worth fell by nearly $5 billion to $265.4 billion. Dell Technologies shares closed at $536.02 that day, down 2.5%, marking a fifth consecutive session of declines. Between September 21 and 24, the stock fell nearly 9% cumulatively.
Still, the recent pullback in Dell’s share price does little to dent its powerful annual run. At the start of 2026, Dell Technologies traded around $127 per share; it has since surged roughly 325%. Earlier in September, Dell’s net worth spiked so sharply that he briefly overtook Google co-founder Larry Page to touch second place on the Forbes billionaires list.
BillionaireCompanyNet worth (USD)Daily changeZuckerbergMeta$266.4 billion+approximately $25 billion (Sept. 21, single day)Michael DellDell Technologies$265.4 billion-approximately $5 billion (Sept. 24)
Note: Net worth figures are Forbes estimates as of the U.S. market close on September 24, 2026.
AI narrative reshapes the wealth landscape
The seesawing fortunes of the two billionaires illustrate two distinctly different paths to benefiting from the current AI wave. Dell Technologies has capitalized on the explosive hardware demand driven by AI infrastructure buildout. The company posted record quarterly revenue of $47 billion in its most recent quarter, including $16.4 billion in AI server sales. Dell’s more than threefold stock gain this year reflects the market’s pricing-in of its central role in the AI compute supply chain.
Meta represents the other path—embedding AI capabilities directly into consumer products used by billions of people. Meta’s second-quarter revenue grew 28% year over year to $60.8 billion. Zuckerberg is steering the company through massive AI investment, with 2026 capital expenditures projected between $130 billion and $145 billion. Muse’s rapid rise offers early validation of this strategy: an AI agent that proactively assists users with tasks is emerging as Meta’s new growth narrative.
Judging by market reaction, investor expectations for Muse already extend beyond raw download metrics. Meta shares have climbed 17.8% since the start of 2026, and have continued to rebound since Muse’s launch this month. Dell Technologies, by contrast, despite its enormous year-to-date gains, has seen five consecutive days of declines—a sign that some capital is taking profits off the table.
The top five spots on the global wealth rankings have shifted multiple times within just a few weeks, reflecting the rapid rotation in valuation logic across different segments of the AI value chain. Zuckerberg’s ascent to fourth place globally marks a moment when the commercial value of consumer AI applications is gaining simultaneous confirmation from both capital markets and wealth rankings.
