[Edaily Reporter PARK MIN ] On the 12th, the KOSPI finally fell below the 6,400 mark for the first time in two months amid a fierce selling spree by foreign investors. On that day, SamsungElectronics(005930)and SK hynix(000660)led the market lower, each falling by more than 4%, as investor sentiment weakened due to high oil prices stemming from the Middle East conflict, interest rate hikes, and doubts about the profitability of artificial intelligence (AI). In particular, the market is believed to have faced strong downward pressure due to concerns over a supply-demand gap as INICS Corporation’s share buyback program—which had been propping up the market—neared its conclusion.

According to MP Doctor, as of 3:35 p.m. that day, the KOSPI closed regular trading at 6,384.24, down 241.69 points (3.65%) from the previous trading day. The index opened at 6,578.17, down 47.76 points (0.72%) from the previous close, and continued to trend downward throughout the session, falling as low as 6,375.61. This marks the fourth consecutive trading day of declines.

By investor type, foreign investors led the decline by maintaining a net selling stance for the fifth consecutive trading day. Foreign investors recorded net sales of 2.0186 trillion won on the day, while institutions—which had shown net buying early in the session—shifted to net sales of 110.7 billion won, joining the selling pressure. Retail investors made net purchases of 1.4674 trillion won, but this was insufficient to stem the fierce selling pressure.

At the same time, the KOSDAQ also closed at 849.19, plummeting 43.08 points (4.83%) from the previous trading day. In the KOSDAQ market, foreign investors made net sales of 27 billion won and institutions made net sales of 222.8 billion won, while retail investors made net purchases of 248.8 billion won. With only 223 stocks rising and 1,465 stocks falling, a strong sense of panic selling was evident across the market.

Among the top-volume stocks on the KOSPI, large-cap IT stocks—led by the leading semiconductor stock, whose share buyback program is nearing completion—collapsed across the board.

SK hynix(000660)closed at 1,605,000 won, down 4.52% from the previous trading day, while SamsungElectronics(005930)also plummeted 4.39% to 250,500 won, threatening to fall below the 250,000 won mark. Related stocks such as SKSQUARE(402340)(-6.29%), SamsungElectroMechanics(009150)(-3.82%), and SamsungElectronics(1P)(005935)(-3.71%) also fell in tandem.

In particular, LG Innotek, whose operating profit forecast was lowered due to the decline in the won-dollar exchange rate, plummeted 16.17%, while HYOSUNG HEAVY INDUSTRIES(298040)(-10.10%) and LGELECTRONICS(066570)(-7.88%) also saw double-digit percentage drops. Leading secondary battery stocks, such as SAMSUNG SDI CO.,LTD.(006400)(-1.41%) and LG Energy Solution(373220)(-0.75%), were also unable to escape the downturn.

Among the top-traded stocks on the KOSDAQ, technology growth stocks—including semiconductor materials, parts, and equipment, as well as robotics—were also unable to avoid sharp declines.

ROBOTIS(108490), the leading robotics stock, closed at 257,000 won after plummeting 13.61%, while LEENO Industrial Inc(058470)(-11.15%) and SIMMTECH Co., Ltd.(222800)(-10.36%) also recorded double-digit declines. HPSP Co., Ltd.(403870)(-5.57%), JUSUNG ENGINEERING Co.,Ltd.(036930)(-5.42%), #Deoksan Nepcores (-3.59%), PSK INC.(319660)(-3.51%), and WONIK IPS Co.,Ltd.(240810)(-2.09%)—major materials, parts, and equipment stocks—also fell across the board.

In contrast, only a few stocks, such as RaonSecure Co., Ltd.(042510), a cybersecurity-themed stock, which rose 6.24%, and SAMPYO Cement Co., Ltd.(038500)(4.66%), posted gains.

By sector, the shipping sector closed up 4.86%, buoyed by expectations of rising freight rates due to the escalating conflict in the Middle East, driven by strong gains in STX Green Logis(465770)(+8.99%), PanOcean(028670)(+6.97%), HMM(011200)(+4.81%), HeungaShipping(003280)(+3.08%), and KoreaLine(005880)(+2.71%). Sectors expected to benefit from high interest rates—such as property and casualty insurance (1.83%), credit cards (1.70%), tobacco (1.58%), and airlines (1.14%)—also held up well with gains.

In contrast, the manufacturing and technology sectors as a whole were hit by a severe sell-off. The electronics sector plummeted 7.66%, recording the largest decline, while machinery (-7.30%), electrical equipment (-6.67%), stationery (-6.54%), and retailers (-6.04%) all ranked among the top decliners.

The securities industry cites the fact that the “defense mechanism” provided by “other corporate investors,” which had been propping up the domestic stock market, is disappearing as the key downward factor, as the massive share buybacks by SamsungElectronics and SK hynix—totaling 55 trillion won—are effectively entering their final stages.

In addition, analysts note that macroeconomic headwinds are exerting strong downward pressure on the market, as geopolitical risks in the Middle East—including the possibility of U.S. military intervention following the attack on Riyadh Airport in Saudi Arabia—have resurfaced, pushing international oil prices above $100 per barrel and causing the yield on the 10-year U.S. Treasury note to breach 5.3% during trading.

In particular, while all three major U.S. stock indices in New York rose on the 9th (local time), semiconductor stocks continued to underperform relative to the broader market, which also weighed on the domestic stock market. Amid concerns over a slowdown in demand following memory price hikes, shares of memory companies such as Micron (-0.66%), SanDisk (-1.72%), and SK hynix American Depositary Receipts (ADRs) (-0.86%) fell, and the Philadelphia Semiconductor Index dropped 0.41%.

Foreign media reports that AI company OpenAI’s annualized revenue as of the end of last month stood at $50 billion—below market expectations ($68 billion to $70 billion)—further amplified doubts about AI profitability. Although it was later revealed that OpenAI’s revenue had not actually declined but was merely the result of a difference in accounting methods, this failed to restore the sharply weakened investor sentiment.

Industry experts advise a conservative approach until it is confirmed that foreign investors are returning to the market and international oil prices have stabilized, as uncertainty regarding the interest rate path could widen again depending on the results of the U.S. Consumer Price Index (CPI) and Producer Price Index (PPI) for September, which are set to be released later this week.

Han Ji-young, an analyst at KIWOOM Securities, stated, “It is undeniable that market concerns surrounding the ‘super cycle’ narrative for semiconductors—the market’s leading sector—as well as issues regarding earnings visibility and sustainability beyond 2027, have not been fully resolved.” She added, “We have reached a point where it is crucial to assess how much next year’s earnings estimates for SamsungElectronics and SK hynix can be revised upward, and the extent to which this will drive upward revisions in earnings estimates for the KOSPI as a whole.”