In brief

• Brent crude rose 2.6% to $111.66 a barrel, its highest in five months, as the Nasdaq fell 1.5% and the S&P 500 lost 0.8% by mid-morning in New York.
• South Korea's Kospi fell 3.52%, Japan's Nikkei 225 dropped 2.65% and Hong Kong's Hang Seng lost 3.03%, a week after the Kospi's 7.57% plunge on Oct. 15.
• The 10-year Treasury yield stood at 5.03%, up from 3.97% before the Iran war, with the Fed's next rate decision due Oct. 28.

Brent crude, the global benchmark price for oil, jumped 2.6% to $111.66 a barrel on Thursday, its highest level in five months, as AI-linked stocks slid and dragged markets lower from Asia to Wall Street.

By mid-morning in New York, the Nasdaq, an index heavy with tech companies, was down 1.5% and the S&P 500, which tracks 500 of the largest US companies, had lost 0.8%.

Nvidia, the largest US company by market value, fell 2.3% and weighs so heavily on the S&P 500 that its slides reach the index funds inside many retirement accounts. Gasoline prices jumped 9.1% in September alone, which means the same oil shock rattling the stock market is already showing up at the pump.

South Korea's Kospi, the country's benchmark stock index, fell 3.52% to 5,533.77 after a recovery yesterday, while Japan's Nikkei 225 dropped 2.65% and Hong Kong's Hang Seng lost 3.03%. China's CSI 300, which tracks 300 large companies listed in Shanghai and Shenzhen, entered a bear market, the term for a fall of 20% or more from a recent peak.

The selloff followed the Kospi plunging 7.57% in a single session on Oct. 15 that local coverage dubbed “Black Thursday,” triggering a circuit breaker, an automatic trading pause meant to calm panic selling. The index is still more than 40% below its June peak.

CoreWeave, which borrowed to buy Nvidia chips that it rents out to other companies through the cloud, fell 3.8% on worries about its debt. Meta dropped 5.8% after its profit missed forecasts, and Lam Research, a chip equipment maker, slid 7.7% after guiding profit slightly below analyst estimates.

Citadel founder Ken Griffin said Tuesday that investors are “almost certainly” in an AI bubble, comparing AI chips to airline seats that cost little to run once bought, so prices can collapse when supply outruns demand. He did not tell investors to sell, but his message still feels contrarian in the middle of a market that has been permabullish since the advent of ChatGPT back in 2023.

The Federal Reserve’s next decision comes Oct. 28, with markets pricing roughly a 15% chance of another hike and a December increase still widely expected. This may be at least partially priced in, but a hike would be bad news for the markets as it makes investments more expensive.

Core PCE inflation data, a price measure that strips out food and energy, follows Oct. 29, and October payrolls arrive Nov. 6.

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