Tech billionaires add a record $845bn in nine months on AI-driven US stocks

Net the non-tech loss against the tech gain and the index rose about $783bn over the nine months ^[27]. Musk's gain is 39.6% of that net figure ^[11]. That matches the Economic Times version of Bloomberg's report: roughly 40% of the index's total increase ^[3]. Mezha.net's summary sets the 40% against the tech group's gain instead ^[4]. Measured that way the share is 36.7% ^[13].

The gains are also geographically narrow. Americans accounted for 94% of the net gain ^[6], about $736bn ^[28]. Since Sept. 10 all ten of the world's richest people have been American, the first time since Bloomberg began tracking billionaires in 2012 ^[8].

Single stock and deal events move these fortunes quickly. The report ties the surge to the AI boom and rising tech stocks, particularly in the US ^[2]. Larry Ellison gained $89bn in one day in September 2025 after Oracle touted growth in its AI-linked cloud infrastructure business ^[14]. A year later his net worth is down $196bn ^[15]. Mark Zuckerberg added $23bn as Meta shares rose 27% in September, their best month in almost four years, after the company rolled out its Muse personal AI assistant ^[10]. Musk briefly became the world's first trillionaire when SpaceX merged with xAI and went public in June ^[9].

For this year's gains to say anything about next year's AI budgets, two things have to hold. Share prices have to stay up. The borrowing behind the buildout has to keep getting financed. According to the report, the debt binge behind Big Tech's AI ambitions is making some investors uneasy ^[17], and Oracle is the example it gives ^[16]. The report does not split the gain between listed shares and private funding-round valuations.

I think the new entrants are the more useful part of the list for a builder, and several of them are outside the US. Michael Dell's wealth rose 81% to $254bn as Dell's data center sales grew ^[12]. Lin Tsung-chi, who founded Taiwan's King Slide four decades ago, now has a $9.5bn fortune built on server rails and cable management systems ^[19]. Wang Xin, chair of Guangdong Dtech, joined on demand for the drill bits used to assemble circuit boards ^[20]. Two Samsung heirs joined on demand for memory chips ^[21]. Read in order, it is a parts list for a data center. On the model side, all seven Anthropic co-founders joined in June after a round valued the company at $965bn ^[22], and the founders of China's MiniMax and DeepSeek were added ^[23].

Among the top 100 or 1,000 richest, "a lot of them are young tech entrepreneurs," said James Mazeau, an economist at UBS's chief investment office ^[24]. "I wonder to what extent that will fuel more wealth concentration," he said ^[25].