South Korea's benchmark KOSPI index surged early before reversing gains to close lower for a third consecutive session. Data from the Korea Exchange (KRX) showed that the trading week was shortened due to holidays, with the index facing notable pressure throughout the week. The KOSPI ended the day down 2.6% at 6,625.93 points, extending its three-day losing streak.

In early trading, the index opened marginally higher by 0.1% at 6,808.68 points, lifted by Samsung Electronics (KRX: 005930) releasing strong preliminary earnings. Although heavyweight stocks briefly rallied at the open, they subsequently faced concentrated profit-taking from foreign and institutional investors, and a broad pullback in chip stocks became the main driver dragging the index into negative territory and pushing it steadily lower. With the holiday-shortened trading schedule, the KOSPI fell 5.4% for the week under the dual pressures of risk-averse sentiment and sector rotation. Market analysts noted that although core technology giants demonstrated solid fundamental profitability, expectations of hawkish Federal Reserve policy pushed U.S. Treasury yields higher, while surging international crude oil prices fueled inflation concerns, weighing broadly on Asia-Pacific markets. Large outflows of overseas capital amplified the magnitude of the KOSPI's weekly pullback.

Samsung Electronics (KRX: 005930) released preliminary earnings on Thursday showing strong third-quarter results, driven by explosive growth in artificial intelligence (AI) chip demand. For the July-to-September period, Samsung estimated operating profit at 107.4 trillion Korean won (approximately US$80.17 billion), a nearly eightfold surge of about 783% compared with 12.17 trillion won in the same period last year. This marked a fourth consecutive quarter of record highs and also exceeded the market forecast of 106.1 trillion won. Third-quarter revenue was estimated at 195 trillion won, up 127% year-on-year. As the pace of AI infrastructure buildout has far outpaced the capacity expansion of memory chips, prices for conventional DRAM, NAND flash, and high-bandwidth memory (HBM) essential for AI have continued to soar, and this supply-demand gap is expected to persist through 2027. Detailed profitability figures for each business division will be disclosed in the official earnings report later this month.

According to people familiar with the matter, South Korea is drafting regulatory rules to prohibit investment banks without a domestic securities license from arranging offshore bond issuance for Korean issuers. Documents seen by media showed that South Korea's Ministry of Economy and Finance has sought industry feedback on the new rules from the Korea Financial Investment Association, which distributed a survey questionnaire last week. The Ministry said the government aims to address regulatory gaps arising from unlicensed investment banks conducting business domestically and to align regulation with international standards. The sources added that Korean regulators are concerned that current rules are unfair to institutions holding full licenses, as licensed institutions bear local operating costs while unlicensed foreign institutions do not. Data showed that the scale of offshore bond issuance by Korean issuers jumped 31% year-on-year this year, reaching US$65.6 billion.