South Korea KOSPI Drops 7% Amid US CPI and AI Doubts

South Korea's stock market took a heavy blow on Thursday morning. The country's primary stock index fell sharply after unexpected economic news from the United States shaken investor confidence worldwide.

A Sharp Drop Triggers Market Safeguards

The Korea Composite Stock Price Index, commonly known as the KOSPI, opened 5.59% lower at 5,673.01. The sudden drop triggered a temporary pause on automated sell orders at 9:08 a.m.

This emergency pause mechanism is called a sidecar. It stops automated program sell orders for five minutes whenever KOSPI 200 futures drop by 5% and stay there for at least one minute.

Despite the temporary pause, selling continued as the morning progressed. By 10:13 a.m. Seoul time, the index slid down 7.28% to 5,571.27.

This decline marks a six-session losing streak for South Korea's benchmark index. The KOSPI is now down roughly 40% from its record high set on June 19.

Even after this steep fall, the index is still up 31.87% overall for 2026, according to data from TradingView. Note: Past performance of financial assets or stock indices does not guarantee future results.

Surprising US Inflation Spooks Global Markets

The major reason behind Thursday's drop came from fresh US economic data. The US Labor Department announced that the Consumer Price Index (CPI) reached 3.7% in September.

Most economists had expected inflation to come in slightly lower at 3.6%. Meanwhile, core CPI—which removes volatile food and energy costs—came in at 2.6%, also beating forecasts.

The hot inflation report sent immediate shockwaves through Wall Street on Wednesday. The S&P 500 dropped 1.11%, while the tech-focused Nasdaq Composite fell 1.88%.

Tech Giants and Memory Chipmakers Take a Hit

South Korea's biggest technology stocks felt heavy pressure right after the market opened. Electronics giant Samsung Electronics slid 6.03%, while rival chipmaker SK Hynix plummeted 7.61%.

Foreign investors were quick to exit their positions early in the session. Net selling from international funds totaled 285.6 billion won in the early hours.

Both Korean chip makers were already facing market pressure due to technological advances from rival ChangXin Memory Technologies in China, which has heightened competition in the memory sector.

Global artificial intelligence leaders were impacted as well. Leading AI graphics card creator NVIDIA saw its stock price drop more than 3% on Wednesday as investors questioned AI sector valuations.

Interest Rate Concerns and Oil Prices Darken Outlook

The unexpected jump in US inflation revived concerns that the Federal Reserve might raise interest rates again during its meeting on October 27 and 28.

The US central bank previously raised interest rates back in September. Higher interest rates increase borrowing costs for technology firms building expensive AI data centers using debt.

Global energy costs are adding another layer of uncertainty. Brent crude oil prices remained near $106 per barrel due to ongoing geopolitical tensions in the Middle East.

Earlier this week, a broader sell-off in Asian stock markets had already dampened risk appetite globally. Investors now turn their attention to the Fed's decision on October 28 to see if market pressure will ease.