South Korea Stocks Tumble as AI-Fueled Rally Faces Profit-Taking Pressure

South Korean stocks suffered a sharp decline on Tuesday, with the benchmark KOSPI plunging nearly 6% as investors rushed to lock in profits after a historic rally driven by artificial intelligence (AI) optimism, semiconductor stocks, and strong foreign investor inflows.

The steep selloff prompted the Korea Exchange to activate a sidecar trading curb, temporarily suspending program trading after stock futures fell significantly. Investor sentiment was further weakened by reports that South Korea would not be added to the MSCI Developed Markets Index during the upcoming review, disappointing expectations for increased foreign investment.

The KOSPI dropped to around 8,600 points after reaching record highs last week. Despite the correction, the index remains up roughly 80% year-to-date, making it one of the best-performing major stock markets globally in 2026. Market analysts noted that concerns over elevated valuations and the rapid pace of recent gains encouraged investors to take profits.

Technology and semiconductor shares led the decline. SK Hynix fell more than 6%, while Samsung Electronics lost over 5%, dragging the broader market lower. Several mid-cap and small-cap stocks also posted double-digit losses, highlighting the widespread nature of the market retreat.

Even with Tuesday’s downturn, semiconductor companies remain central to South Korea’s investment story. SK Hynix recently surpassed Samsung Electronics to become the country’s most valuable publicly traded company, marking a major milestone in the AI-driven transformation of the semiconductor industry.

Shares of SK Hynix have surged more than 340% this year thanks to its leadership in high-bandwidth memory (HBM) chips, a critical component powering advanced AI systems from major technology companies such as Nvidia and Alphabet. The company’s growing dominance in the HBM market has helped fuel its extraordinary rise.

However, SK Hynix shares came under pressure following local media reports suggesting the company may reduce HBM production and focus more on higher-margin DRAM products. Despite short-term concerns, analysts continue to view the company as a key beneficiary of the global AI boom.

The recent market correction underscores the volatility that can accompany strong rallies, but South Korea’s semiconductor sector remains a major force behind investor interest and long-term growth expectations.