On Monday, South Korea's stock market once again faced heavy selling pressure, with foreign capital withdrawing billions of dollars from the market. At the same time, concerns about the sustainability of the country's semiconductor growth driven by artificial intelligence are also on the rise.

The benchmark KOSPI index fell 3.65% on October 12, closing at 6,384.24 points, marking the lowest closing level since August 11. The index has been declining for four consecutive trading days, with a cumulative decline of 8.85% during this period.

The KOSDAQ index, which is mainly composed of technology stocks, performed even worse, falling by 4.83% to close at 849.19 points.

Samsung Electronics and SK Hynix lead the decline in the South Korean stock market

Some of South Korea's largest technology companies were at the center of the decline on Monday. Samsung Electronics' stock price fell by 4.39%, while SK Hynix, the leader in artificial intelligence storage chips, saw a drop of 4.52%. SK Square tumbled by 6.10%, and Hyundai Motor, Samsung Biopharmaceuticals, and LG new energy companies also closed lower.

Despite the strong underlying profitability of the semiconductor industry, related stocks still experienced declines.

Samsung Electronics is expected to announce a significant year-on-year increase in third-quarter operating profits, partly due to strong demand for chips used in the AI infrastructure. However, as the pace of rising storage chip prices has begun to slow down, analysts have recently lowered their profit forecasts.

This has also raised doubts in the market about whether the previous substantial gains in South Korean semiconductor stocks can be sustained.

AI Worries That Rising Oil Prices Increase Market Pressure

This sale comes at a time when investors are re-evaluating the global valuation of AI. South Korea has always been one of the biggest beneficiaries of the surge in demand for storage chips used in AI data centers, which also helped the KOSPI index soar earlier this year.

However, current market sentiment is being dragged down by concerns regarding the profitability of semiconductors and the sustainability of the upward cycle for memory chips.

Rising oil prices and new tensions in the Middle East region have added another layer of uncertainty. Higher energy costs may keep global inflation at high levels and further increase interest rate pressures, thus creating a more difficult environment for highly valued tech stocks.

Despite recent corrections, the South Korean stock market has still seen a significant rise in 2026. Therefore, this latest decline is more of a sharp reversal from one of the strongest gains in the global stock markets this year, rather than the previous gains being completely erased.