Japan's benchmark Nikkei index tumbled nearly 5% on Thursday, its worst session in months, as a double dose of bad news for the AI trade—hotter-than-expected US inflation and fresh worries about the debt load of cloud-computing provider CoreWeave—sent investors scrambling out of leveraged technology stocks and into defensive sectors like pharmaceuticals.
The sell-off was led by the very names that had powered the market's recent rally. Chip-testing firm Advantest fell 13.9%, chipmaking-equipment giant Tokyo Electron dropped 7.3%, and SoftBank, the investment group with heavy exposure to AI startups, slid 9.4%. The moves were a stark reminder that when the cost of money rises, the most expensive, debt-dependent corners of the market tend to suffer the most.
Two stories, one pressure point: the cost of money
The trigger for Thursday's rout was a US consumer price index (CPI) report that came in hotter than economists had expected. CPI measures the average change in prices paid by consumers for goods and services, and a higher-than-forecast reading revives fears that the Federal Reserve will keep interest rates elevated for longer. Higher rates raise borrowing costs for companies and reduce the present value of future earnings—a double whammy for growth stocks that trade on expectations of big profits years down the road.
At the same time, media reports flagged stress in parts of CoreWeave's debt. CoreWeave, a US provider of cloud computing services heavily used for AI training, saw its shares plunge more than 15% even after its CEO insisted that the company's deal backlog—the value of contracted future business—would be enough to cover its obligations. The company's debt concerns are not new; they have been a recurring theme in the AI trade, as CoreWeave has been flagged as a potential weak link in the AI buildout. The CEO's defense, detailed in his recent comments on the $104 billion backlog, did little to calm investors on Thursday.
The logic that connects these two stories is simple: if big buyers of AI computing face tighter credit or pricier refinancing, some data-center projects get delayed or scaled back. And because equipment makers like Tokyo Electron and Advantest are valued on expected future orders, even small changes in spending assumptions can lead to outsized moves in their share prices.
Risk-off rotation: pharma shines
The flip side of Thursday's sell-off was a classic risk-off rotation. Pharmaceuticals, a sector known for steady demand and defensive characteristics, was Tokyo's best-performing industry group, rising 3.4%. Sumitomo Pharma jumped 13%, leading the charge. Investors were clearly seeking shelter in companies whose earnings are less tied to the boom-and-bust cycle of capital spending.
This pattern—selling high-growth tech and buying defensive sectors—is a familiar one when inflation surprises to the upside. It echoes what happened in other Asian markets, where hot US inflation hit tech stocks and sent Korea's KOSPI down 5.6%. The same forces are pressuring Indian stocks, where foreign selling has hit record levels.
What it means for investors
For everyday investors, Thursday's move is a reminder that the AI trade is not a one-way bet. CoreWeave's 15% drop put Tokyo Electron and Advantest under a harsher spotlight, but the real issue is broader: how will the next wave of AI data centers be funded?
CoreWeave matters less because it's one stock and more because it's a test case for the entire AI buildout. When markets start questioning an AI infrastructure company's balance sheet, lenders and investors often demand higher returns, which raises the bar for new projects. Those projects might still happen, but later, in smaller phases, or with tighter budgets.
That uncertainty lands first on Japan's AI supply chain. Names like Tokyo Electron and Advantest live and die by customers' capital spending plans, so headlines about refinancing, project finance, or credit conditions can move them sharply even if near-term demand sounds fine. Expect that sensitivity—and volatility—to persist whenever investors reassess who can pay for the next wave of data centers.
For those with diversified portfolios, the rotation into pharma is a textbook example of why holding a mix of sectors can cushion the blow when high-flying tech stumbles. But it also underscores that the AI trade, for all its promise, is increasingly tied to the whims of interest rates and credit markets.
Looking ahead, investors will be watching two things: whether US inflation continues to run hot, and whether CoreWeave and other AI infrastructure players can reassure markets about their financing. The hot CPI report has already rattled AI stocks and sent Japan's bond yields lower, and the impact on tech ETFs and chip stocks has been severe. Until those questions are resolved, expect more sharp swings in the stocks that have led the market higher.
