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Samsung Electronics at 210,000 won, SK Hynix at 1.28 million won; US inflation shock freezes Seoul market

Samsung Electronics at 210,000 won, SK Hynix at 1.28 million won; US inflation shock freezes Seoul market

[Market Open]
U.S. CPI exceeds market forecasts + New York Stock Exchange weakness
Major semiconductor stocks plunge, KOSPI-KOSDAQ sell-side sidecar (futures market circuit breaker) triggered

On the morning of the 15th, a large electronic display board at the Hana Bank headquarters dealing room in Jung-gu, Seoul shows market conditions including the KOSPI. On this day, the KOSPI fell by 335.80 points (5.59%) from the previous trading session to 5673.01, the KOSDAQ dropped by 39.43 points (4.79%) to 784.45, and the won-dollar exchange rate is showing the low 1,340-won range. October 15, 2026/NEWS1
On the morning of the 15th, a large electronic display board at the Hana Bank headquarters dealing room in Jung-gu, Seoul shows market conditions including the KOSPI. On this day, the KOSPI fell by 335.80 points (5.59%) from the previous trading session to 5673.01, the KOSDAQ dropped by 39.43 points (4.79%) to 784.45, and the won-dollar exchange rate is showing the low 1,340-won range. October 15, 2026/NEWS1

With the impact of U.S. inflation indicators and semiconductor stock weakness overlapping, sell-side sidecar (futures market circuit breaker) was simultaneously triggered in both the KOSPI and KOSDAQ markets for the first time in two and a half months. Major semiconductor stocks are particularly weak, with Samsung Electronics and SK Hynix falling by 6% and 8%, respectively.

As of 9:18 a.m. on the 15th, the KOSPI stood at 5633.44, down 375.37 points (6.25%) from the previous trading session. The KOSPI opened at 5673.01, down 5.59%, and is widening its decline.

At the same time, the KOSDAQ stood at 771.01, down 52.87 points (6.42%). The KOSDAQ also opened at 784.45, down 4.79%, before falling to the 6th% range.

Futures indices for both major markets fell together from the start of trading, triggering sell-side sidecar (futures market circuit breaker) for the first time in about two and a half months since July 29. The sidecar (futures market circuit breaker) was triggered at 9:07 a.m. for the KOSPI and at 9:12 a.m. for the KOSDAQ, respectively, halting program trading effectiveness for five minutes.

In the KOSPI, foreign investors were net sellers while institutional investors were net buyers, with retail investors turning to net buying as of 9:19 a.m. As of 9:24 a.m., according to Korea Exchange data, institutional investors made net purchases of 702.7 billion won and retail investors made net purchases of 11 billion won, while foreign investors sold off 759 billion won.

In the KOSDAQ, bargain-hunting buying by foreign and institutional investors is flowing in. Retail investors were net sellers of 56.9 billion won, while foreign investors and institutional investors made net purchases of 44.8 billion won and 14 billion won, respectively.

Looking at top market capitalization stocks, major semiconductor stocks show particular weakness. Samsung Electronics is trading at 216,500 won, down 15,500 won (6.68%) from the previous trading session. SK Hynix is trading at 1,294,000 won, down 125,000 won (8.81%). SK Square plunged in the 9th% range, and Samsung Electro-Mechanics plunged in the 12th% range. LG Energy Solution, Hyundai Motor, and Samsung Life Insurance fell in the 3rd% range, while Samsung SDI fell in the 5th% range and Samsung C&T fell in the 6th% range.

Samsung Electro-Mechanics, considered a leading stock in semiconductor substrates, plunged in the 12th% range, ceding its fourth-place spot in market capitalization to LG Energy Solution.

In the KOSDAQ market as well, semiconductor-related stocks are falling across the board. Jusung Engineering fell in the 12th% range, while Simmtech and HPSP plunged in the 10th% range. Among top KOSDAQ market capitalization stocks, Ecopro BM fell in the 8th% range, RAINBOW Robotics and Iotech in the 7th% range, and Lino Industrial in the 6th% range. With all top market cap stocks showing red, including Alteogen and Samchundang Pharm falling in the 4th% range.

In the KOSPI, all industries/sectors fell except for food, beverage, and tobacco which were up in the 1st% range, and pharmaceuticals and entertainment/culture which were slightly flat. In particular, medical/precision instruments fell in the 8th% range, and electrical/electronics fell in the 7th% range.

In the KOSDAQ, all industries/sectors fell except for publishing/media which surged in the 12th% range, and entertainment/culture which was slightly flat. Machinery/equipment and non-metals fell in the 9th% range, electrical/electronics fell in the 8th% range, and pharmaceuticals were weak in the 3rd% range.

The weakness in major semiconductor stocks is interpreted as being influenced by U.S. inflation indicators and the overnight weakness of AI/semiconductor stocks on the New York Stock Exchange. The U.S. September CPI (consumer price index) rose 3.7% year-on-year, slightly exceeding market expectations (3.6%). Core CPI rose 2.6% year-on-year and 0.3% month-on-month, both exceeding market forecasts.

As U.S. inflation indicators exceeded expectations, raising the outlook for base rate hikes, AI/semiconductor stocks were weak on the New York Stock Exchange amid concerns over AI investment debt. Micron Technology fell in the 3rd% range, while AMD fell in the 5th% range, and Intel and SanDisk fell in the 4th% range.

Han Ji-young, a researcher at Kiwoom Securities, noted, "The market's evaluation criteria for the AI investment cycle are shifting from the scale of CAPEX (capital expenditure) expansion to the profitability of invested capital and the stability of funding." She added, "The Q3 big tech earnings season will be a test proving how much more profit and cash flow AI investments can generate compared to the previous quarter."

Forecasts emerged that the domestic stock market would narrow its decline during trading after opening lower. Researcher Han Ji-young analyzed, "Inflow of technical buying following seven consecutive trading days of sharp declines, along with digesting the TSMC earnings event scheduled for release in the latter half of the session, will lead to a narrowing of the decline." She added, "In the short term, whether the KOSPI, including semiconductors, can hold its all-time low amid unfavorable foreign supply and demand conditions is a key issue."

On the Seoul foreign exchange market on this day, the won-dollar exchange rate traded at 1,339.5 won, up 1.2 won from the previous trading session's daily closing price.

"This article was translated using AI and may differ slightly from the original."