South Korean shares fall more than 7% as tech sell-off follows US inflation data

South Korea's benchmark stock index fell by more than 7% on 15 October 2026, according to AP and The Guardian. The fall came as a sell-off in technology shares deepened. It followed a decline in US stocks after US inflation data came in higher than expected.

According to The Guardian, the Kospi 200 index fell more than 8% and closed at a six-month low, down 8.1%. The outlet reported that the fall triggered circuit breakers that halted trading at various points. AP reported that South Korea's benchmark Kospi index had dropped by more than 7% as the sell-off of technology shares deepened. The AP report reviewed by Vocemundi is a summary only.

The Guardian reported that SK Hynix shares fell nearly 11% and Samsung Electronics shares fell 9.5%. Japan's Nikkei 225 fell 4.9%. Memory chip maker Kioxia fell 11%. SoftBank, an investor in OpenAI, fell 10%. Shanghai's CSI 300 index fell as much as 2.4%, its lowest level since August 2025. TSMC shares fell 2%, even though the company reported its sixth straight quarter of profits.

In the previous US session, the Nasdaq Composite fell 1.9% and the S&P 500 fell 1.1%, according to The Guardian. This was the S&P 500's worst performance since July. US consumer price inflation rose to 3.7% in September. The Guardian said this was the fastest rate since CPI reached a three-year peak of 4.2% in May. According to the outlet, investors now expect fresh interest rate increases by the US Federal Reserve. Some are pricing in an increase as soon as the end of the month.

European indices fell at the start of trading. The Stoxx 600 was down 0.4% and the DAX down 0.53%. Nasdaq 100 futures were down 1%.

What each side says

The Guardian characterised the sell-off as driven by fears over rising inflation and future rate hikes, among traders already wary of the heavily indebted AI sector.

The Guardian quoted Deutsche Bank analysts led by Jim Reid as saying: "Markets have just had an incredibly tumultuous 24 hours, as a strong US CPI print was then followed up with mounting fears around the AI trade." The outlet also quoted Reid as saying: "This wasn’t just an energy surge driving prices higher, as there were broad-based moves across the consumer basket."

Earlier in the week, the International Monetary Fund warned that the threat of an AI share price crash spreading across global markets was putting world financial stability at risk, The Guardian reported. "The consequences of an AI correction could be global," the IMF said, according to the outlet.

What the reports do not include

The reports reviewed by Vocemundi do not include the official CPI release, any Federal Reserve statement, or comment from the companies named or South Korean regulators. They do not establish direct causation between the inflation data and the share falls.

Analysis

The falls show how inflation data in one economy can coincide with sharp moves elsewhere, especially in markets with heavy exposure to technology and chip shares. If inflation stays above expectations, markets may continue to price in higher US interest rates, which could weigh on highly valued or indebted sectors. If later data eases those concerns, some pressure could lift. The IMF's view that Asian markets would be most exposed outside the US offers one framework, but the reports reviewed by Vocemundi do not establish causation. The closing levels of later sessions will matter for any assessment.

Produced by the Vocemundi newsroom with AI assistance.