Seoul — October 06, 2026. Published after the market close; stock and index prices are official closing values, while continuously traded quotes such as the won-dollar rate and US Treasury yields are market levels rather than official closes.
The 30-second version
- The KOSPI fell 0.89% to 6,941.39, giving back the 7,000 level as foreign investors sold roughly 1.75 trillion won (about $1.3 billion) of KOSPI shares.
- The KOSDAQ jumped 2.98% to 919.92 — its first approach to the 920 line in three months — led by biotech, batteries, and semiconductor equipment.
- The split traces back to the US: Treasury yields hit 24-year highs (10-year at 5.328%), yet the Nasdaq still closed at a record. Korea imported both halves of that trade.
- Samsung Electronics fell 1.45% and SK hynix dropped 3.69%, while Jusung Engineering (+16.77%) and HLB (+16.38%) led the small-cap charge.
- Samsung’s preliminary Q3 results arrive October 8; analyst consensus points to the first 100-trillion-won quarterly operating profit by any Korean company — a forecast, not a fact, yet.
One country, two very different closes
Tuesday was a tale of two boards. On the KOSPI — Korea’s main exchange, home to the big exporters — foreign investors net sold somewhere between 1.75 and 1.77 trillion won (domestic reports varied slightly), and that single flow did most of the damage. Retail investors bought the dip, adding 725.6 billion won (roughly $540 million), while institutions trimmed a modest 59.4 billion won. It wasn’t enough: the index closed at 6,941.39, down 62.35 points.
The KOSDAQ — the growth-and-small-cap venue, loosely Korea’s Nasdaq — ran the opposite direction. Institutions and other corporate accounts each bought a net 105.7 billion won, lifting the index 2.98% to 919.92. Interestingly, retail investors sold 221 billion won of KOSDAQ shares even as they bought the KOSPI, and foreigners were small net sellers there too (-123.2 billion won). In other words, today’s KOSDAQ rally was institution-driven, while today’s KOSPI slide was foreigner-driven — a clean role reversal from the usual script.
The why: bond yields versus the AI trade
The trigger came from New York. The US 10-year Treasury yield reached 5.328% and the 30-year touched 5.6959% intraday — the highest in 24 years. Fed Governor Lisa Cook warned that AI-driven demand and rising oil prices are keeping inflation pressure alive, and futures markets (CME FedWatch) now price a 72.52% probability of a rate hike at the October FOMC meeting.
Normally that combination sinks everything. But in the previous US session (October 5), the Nasdaq rose 1.05% to a record 27,477.31, with the S&P 500 up 0.66% and the Dow up 0.18%, as AI heavyweights like Nvidia and Broadcom shrugged off the bond market. The theme Korean strategists kept repeating: “AI over rates.”
Korea absorbed both signals at once. Rate-sensitive, foreigner-heavy large caps — above all the two memory giants — got sold, while Nasdaq-correlated growth names on the KOSDAQ caught the tailwind. That is why the same day produced a -0.89% KOSPI and a +2.98% KOSDAQ.
Rotation, not panic
Under the surface, this looked like sector rotation rather than risk-off. Samsung Electronics closed at 272,000 won (-1.45%) and SK hynix at 1,773,000 won (-3.69%), dragging the electrical/electronics sector down 1.38%, with transport equipment (-1.61%) and pharma (-1.55%) also soft. But medical and precision instruments surged 5.70%, and chemicals and utilities also gained. Chip-equipment maker Jusung Engineering jumped 16.77% to 276,750 won, biotech HLB rose 16.38%, Samchundang Pharmaceutical gained 14.98%, and battery-materials maker EcoPro BM added 10.03%. One local tally noted that about 16 of the day’s 20 most-watched stocks closed higher — a breadth picture far healthier than the headline KOSPI number suggests.
| Metric | Close | Change |
|---|---|---|
| KOSPI | 6,941.39 | -62.35 pts (-0.89%) |
| KOSDAQ | 919.92 | +26.63 pts (+2.98%) |
| USD/KRW | around 1,342.6 | little changed |
| Samsung Electronics | 272,000 won | -1.45% |
| SK hynix | 1,773,000 won | -3.69% |
| Jusung Engineering | 276,750 won | +16.77% |
| US 10-year Treasury | 5.328% | 24-year high territory |
One housekeeping note on the currency: the won is continuously traded and has no single official close, so we quote it as around 1,342.6 won per dollar, little changed on the day. Some Korean outlets cited a trade-association base rate of 1,342.10 (-1.29%), which is calculated at a different reference time, so small discrepancies between reports are normal.
What to watch next
- October 8 — Samsung Electronics preliminary Q3 results. FnGuide consensus sits at 108.13 trillion won in operating profit (roughly $80 billion), up 788.79% year over year, on the HBM4 ramp and a memory boom (the memory division alone is estimated near 110 trillion won). This would be the first 100-trillion-won quarter by a Korean company — but it is a pre-announcement consensus estimate, not a reported figure.
- US long-term yields. Whether the 30-year holds near its 24-year-high 5.7% area will set the tone for foreigner-heavy Korean large caps.
- The October FOMC. Markets assign a 72.52% probability to a hike; any shift in that number moves Seoul.
- Foreign flows. Today’s 1.75-trillion-won-scale selling is the thing to monitor — one more day like this would confirm a trend rather than a one-off.
- The range. Kiwoom Securities sees the KOSPI trading 6,800-7,300 this week, with US long rates and Samsung’s numbers as the swing factors.
FAQ
Why did the KOSPI fall while the KOSDAQ rose on October 6, 2026?
Foreign investors sold roughly 1.75 trillion won of KOSPI shares — concentrated pressure on large-cap semiconductors like Samsung Electronics and SK hynix — amid 24-year-high US Treasury yields. Meanwhile the Nasdaq’s record close fueled institutional buying of KOSDAQ biotech, battery, and chip-equipment names, lifting that index 2.98%.
Who was selling Korean stocks today?
On the KOSPI, foreigners were the big sellers and retail investors were the big buyers. On the KOSDAQ it flipped: retail and foreigners sold while institutions and corporate accounts bought.
What is expected from Samsung Electronics’ Q3 earnings on October 8?
Consensus points to about 108.1 trillion won in operating profit — which would be the first 100-trillion-won quarter by any Korean company, driven by HBM4 mass production and the memory upcycle. That remains a forecast until the preliminary release.
Is a US rate hike really on the table?
Per CME FedWatch pricing cited in today’s reports, markets see a 72.52% chance of a hike at the October FOMC, after Fed Governor Lisa Cook flagged persistent inflation pressure from AI demand and oil prices.
Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.
Related reading
Also on Seoul Closing Bell
A companion piece on the same session, written from a different angle: Samsung Electronics Fell as KOSDAQ Chip Equipment Stocks Soared.