Big Short Investor Issues AI Warning: ‘70% of AI Revenue Is Just Two Companies, And One of Them I Think Is in Trouble’
The investor who called the subprime collapse now says the entire AI buildout depends on two companies, and one of them keeps him up at night. His math traces a chain from NVIDIA to Microsoft to a single customer whose…
Steve Eisman, the money manager who shorted subprime and was portrayed by Steve Carell in The Big Short, warned on his September 21 podcast that the AI trade rests on dangerous concentration. “70% of AI revenue of the hyperscalers is just from OpenAI and anthropic,” he said [sic], which amounts to about 25% to 35% of the hyperscalers’ entire cloud revenue. His conclusion: “the entire ecosystem is dependent upon two companies” and “one of them I think is in trouble, which is OpenAI.”
Why the Timing Matters
Eisman’s warning came six days after OpenAI’s CFO tried to reassure the market. On September 15, OpenAI CFO Sarah Friar told CNBC the company’s business is “a diversified set of revenue streams” with strong margins and a diversified chip supply chain. The next day, CNBC reported that investors had approached OpenAI about a new funding round at a valuation as high as $1.5 trillion, with no active raise underway. Within a week, the market heard OpenAI described as either a $1.5 trillion diversified platform or the single point of failure for the entire AI capex cycle.
Eisman offered no source for the 70% figure. If directionally correct, it suggests customer concentration at the top of the AI stack is worse than any 10-K discloses.
Follow the Chain
NVIDIA (NASDAQ:NVDA | NVDA Price Prediction) sits at the head, with a market cap of roughly $5.52 trillion. Fiscal Q2 revenue hit $96.22 billion, up 105.8% year over year, with data center revenue of $89.02 billion. CEO Jensen Huang said compute is “supply-constrained” and guided Q3 revenue to $108.0 billion. Supply commitments have swelled to $279 billion, with $108.5 billion in guarantee obligations to AI cloud and data center partners. NVIDIA has invested nearly $50 billion in the Frontier AI Labs.
Microsoft (NASDAQ:MSFT), market cap $3.68 trillion, is in the middle. Azure crossed $100 billion in annual revenue for the first time. Microsoft spent $115.95 billion on capex in fiscal 2026, and commercial remaining performance obligations hit $678 billion. Free cash flow in Q4 fell to $19.64 billion, down 23% year over year, as capex outran operating cash. Microsoft’s restructured OpenAI deal gave it a ~27% stake valued around $135 billion in exchange for OpenAI contracting $250 billion in incremental Azure services.
That $250 billion is the Eisman question in one line. If OpenAI cannot generate the cash to consume what it promised to buy, the RPO becomes uncollectable and Microsoft’s capex intensity looks less like leverage to a secular boom and more like credit exposure to two loss-making labs.
(The picks-and-shovels case for AI runs well past the chipmakers; we profiled seven suppliers powering the buildout, from power to cooling, in a free report you can grab here.)
What to Watch Next
NVIDIA shares are up 23% year to date and 947.6% over five years. Microsoft is up just 3.02% in 2026 and down 3.62% over the past year. The market is already questioning the ROI math.
Watch whether OpenAI’s next funding round prices near $1.5 trillion and whether Microsoft’s fiscal Q1 earnings report in late October shows Azure growth holding near the 45% constant-currency guide without another decline in free cash flow. If either wobbles, Eisman’s chain gets very short, very fast.
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AJ spent 10 years writing about financial markets at The Motley Fool. His coverage centers on technology stocks and the broader macroeconomic trends, from interest rates to geopolitics, that shape where markets are headed next. AJ is drawn to the stories where big-picture economics and individual companies collide.
