Asian Stocks Tumble as AI Infrastructure Debt and US Inflation Fears Converge

Stock markets across Asia fell sharply on October 15, 2026, led by South Korea's KOSPI, which slumped more than 7%, and Japan's Nikkei 225, which dropped about 5%, according to Nikkei Asia and The National. Hong Kong's Hang Seng lost around 1% and China's Shanghai Composite fell 1.75%, The National reported.

What triggered the sell-off

The immediate trigger was a sell-off on Wall Street a day earlier, after new US consumer price data showed inflation running hotter than forecast. The National reported that September's US consumer price index rose 3.7% year-on-year, above the 3.6% forecast and up from 3.4% in August, while core inflation came in at 2.6% year-on-year, also higher than expected. The figures raised expectations that the Federal Reserve could move toward tighter policy rather than cutting rates, Nikkei Asia and The National both reported.

Layered on top of the inflation surprise was mounting concern about how artificial-intelligence infrastructure is being financed. Nikkei Asia reported growing worry in markets about the scale of debt being taken on to build data centers and buy advanced chips, much of which is borrowed rather than funded from company cash. Analyst Kyle Rodda of Capital.com, quoted by both The National and IndexBox, said the region was dealing with both a deeper pullback in AI-related stocks and tighter financial conditions stemming from higher bond yields and a stronger US dollar.

The International Monetary Fund separately warned that Asia's economies are heavily exposed to any slowdown in AI-related spending because of the region's central role in global technology supply chains, The National and IndexBox both reported, citing the IMF.

Index moves on October 15

Korea's deeper and longer slide

South Korea's market fell further and longer than its neighbors. The Korea Times reported that the KOSPI lost 20.7% over seven trading sessions through Thursday, October 15, closing at 5,554.22, before rebounding 2.05% the following day. Aju Press reported that by the morning of October 19, the index had briefly fallen a further 3.2% before foreign investors turned net buyers and losses narrowed to about 1.6%, with the index trading around 5,576.

According to the Korea Times, foreign investors sold a net 4.54 trillion won of Korean shares in a single session during the losing streak, far exceeding the 51.4 billion won in net purchases that day by pension funds and similar institutions, according to the Korea Exchange figures the paper cited. The Korea Times reported that domestic buyers who had previously cushioned declines had less capacity to keep doing so. The National Pension Service had already expanded its permitted allocation for domestic equities during a mid-year rally and did not sufficiently reduce its stock exposure near the peak, the Korea Times reported, leaving it less room to buy at lower prices during the recent sell-off. It also noted that large corporate share buyback programs were winding down: Samsung Electronics had completed a 15 trillion won buyback by October 6, and SK hynix had already spent 37 trillion of a planned 40 trillion won program.

A second correction after a volatile year

October's drop is not the first sharp swing in the KOSPI this year. The Korea Times reported that the index had already fallen from a peak of 9,385.59 on June 19 to a low of 5,262.77 on July 29, before recovering. The Korea Times also noted that its volatility gauge, the VKOSPI, stood at 56 during the October rout, below the 97 level it reached in June, suggesting markets viewed this episode as less extreme than the earlier one, even as recovery patterns from the summer may not repeat.

The Korea Times reported that short interest in exchange-traded funds tracking South Korean stocks had fallen to 8.7% from 27.7% in July, which analysts said reduces the kind of short-covering that helped fuel the summer rebound. Goldman Sachs estimated the KOSPI's forward price-to-earnings ratio at 5.1 times, a level the Korea Times described as suggesting relatively low valuations despite the uncertainty.

What is not yet known

• None of the sources reviewed report a central bank or government statement declaring the sell-off over or identifying a single cause with certainty.
• The Nikkei 225's single-day move on October 15 is reported slightly differently across sources: Nikkei Asia described it as a decline of nearly 5%, while The National and IndexBox put the figure at 5.12%; this piece reports both as cited.
• It is not yet established how much of the AI-linked debt concern reflects specific companies' financing versus broader market sentiment; sources cited general worry about data-center and chip financing rather than a single disclosed default or loss.