Seoul — September 21, 2026. Published after the market close; index and stock prices are official closing values. The won/dollar rate trades continuously and has no official close — figures here are as-of quotes from the September 21 session.
The 30-second version
- The KOSPI closed at 7,007.72, up 113.49 points (+1.65%), reclaiming the 7,000 line for the first time in seven trading sessions. The KOSDAQ rose 1.11% to 836.27, its fourth straight gain.
- The fuel: Korean semiconductor exports hit a record $34.1 billion in the first 20 days of September, up 259.4% from a year earlier. Samsung Electronics jumped 4.98% and alone traded about 5.85 trillion won (~$4.2 billion) of stock.
- Domestic institutions did the buying (roughly 1.5-1.6 trillion won net on the KOSPI, about $1.1 billion), while retail investors sold heavily and foreigners were essentially flat.
- The catch: only 310 KOSPI stocks rose while 552 fell. This was a narrow, chip-led rally, not a broad one.
- The won firmed slightly, quoted around 1,378 per dollar as of the September 21 session, and the market heads into the last trading week before the Chuseok holiday with a packed event calendar.
Chips did the heavy lifting
Today’s move had one engine: semiconductors. Customs data showing record chip exports of $34.1 billion for September 1-20 — up 259.4% year-on-year — landed on a market already primed by strength in the Philadelphia Semiconductor Index and rising Nasdaq-100 night futures. Money poured into the memory-chip heavyweights that dominate the KOSPI’s market capitalization.
Samsung Electronics closed up 4.98% at 274,000 won, topping the turnover table, and its preferred shares did even better at +6.07%. Samsung C&T gained 4.70%, SK Square 4.45%, and Samsung Electro-Mechanics 2.95%. Interestingly, SK Hynix — usually the high-beta way to play memory — added just 0.59%, though it still traded a hefty 4.8 trillion won (~$3.5 billion). Smaller chip-equipment and materials names ran harder: DI rose 12.74% and KEC 10.68%, while on the KOSDAQ, packaging firm Signetics went limit-up at +30.00%. (Korean exchanges cap single-day moves at 30% in either direction; hitting that ceiling is called a “limit-up” and trading effectively pins there.) Midday reports also pointed to institutional buying concentrated in back-end chip suppliers such as SFA Semiconductor, totaling around 300 billion won for the sector — a figure from intraday coverage rather than the official close, so treat it as indicative.
By sector, medical and precision instruments (+5.47%), retail (+2.47%), and electricals/electronics (+2.39%) led the gains, per Financial News’ closing wrap.
Who was buying — and who was cashing out
The flow picture was unusually lopsided. On the KOSPI, domestic institutions bought a net 1.49-1.60 trillion won (roughly $1.1 billion; end-of-day tallies across Korean wire services differ slightly depending on snapshot timing, but all agree on the direction). Retail investors sold a net 2.98-3.25 trillion won (~$2.2-2.4 billion) into the strength — a classic pattern where individuals take profits as the index pops. Foreign investors, often the swing factor in Seoul, were effectively neutral, selling a modest net 10-170 billion won.
The KOSDAQ flows ran the other way: individuals bought a net 139.2 billion won (~$101 million) while foreigners sold 100.7 billion won and institutions 28.3 billion won.
The “illusion rally” problem
Here is the number that should temper the celebration: 310 KOSPI stocks rose today, but 552 fell. The index gained 1.65% because a handful of mega-cap chip names — which carry enormous index weight — surged, while the median stock actually declined. Korean commentators call this a “chakshi” or optical-illusion rally: the scoreboard says the market is up, but most portfolios that are not concentrated in semiconductors likely were not.
The losers tell the same story. LG Energy Solution fell 3.30% to 352,000 won and Hyundai Motor lost 1.64% to 359,000 won, with battery names like LG Energy Solution and POSCO Holdings still churning on uncertainty around US electric-vehicle policy. Metals (-1.58%), transport equipment (-1.48%), non-metallic minerals (-1.37%), paper and wood (-1.24%), and construction (-0.99%) all closed lower. A rally this narrow can keep going as long as the chip story holds, but it offers little cushion if the leadership stumbles.
Key closing numbers
| Measure | Close / Level | Change |
|---|---|---|
| KOSPI | 7,007.72 | +113.49 pts (+1.65%) |
| KOSDAQ | 836.27 | +9.15 pts (+1.11%) |
| USD/KRW | around 1,378 (Sep 21 as-of quote; no official close) | won slightly firmer |
| Samsung Electronics | 274,000 won | +4.98% |
| SK Hynix | 1,868,000 won | +0.59% |
| LG Energy Solution | 352,000 won | -3.30% |
| KOSPI advancers / decliners | 310 / 552 | |
What to watch next
- Holiday-shortened runway: this week (September 21-25) is the last trading week before Chuseok, Korea’s multi-day harvest holiday, when local markets shut. Positioning ahead of a long closure often amplifies moves.
- Event cluster: a US-China summit, PMI releases, and new IPO listings are all packed into the week, raising the odds of volatility.
- The won at 1,380: the currency was quoted around 1,378 per dollar as of the September 21 session. Market watchers flag that a stable move below the 1,380 line would make won-denominated assets more attractive and could finally pull foreign investors — flat today — back to the buy side.
- Breadth: whether gainers start outnumbering decliners will show if this rally is broadening or staying a one-sector show.
FAQ
Why did the KOSPI go above 7,000 today?
Record semiconductor exports — $34.1 billion in the first 20 days of September, up 259.4% year-on-year — triggered heavy institutional buying of index heavyweights like Samsung Electronics (+4.98%). Because a few chip giants carry outsized index weight, their gains alone lifted the KOSPI 1.65% back above 7,000, as reported in News1’s official closing tally.
If the index rose 1.65%, why did most Korean stocks fall?
Only 310 KOSPI stocks advanced against 552 decliners. The index is capitalization-weighted, so a surge in a few mega-caps can outweigh losses across hundreds of smaller names — a top-heavy pattern local analysts flagged as an “illusion rally.”
Are foreign investors buying Korean stocks right now?
Not meaningfully. Foreigners were roughly neutral on the KOSPI today (a small net sale of 10-170 billion won) and sold about 100.7 billion won net on the KOSDAQ. Today’s buying came almost entirely from domestic institutions; a firmer won below 1,380 per dollar is the trigger many watch for foreign inflows to resume.
Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.
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Also on Seoul Closing Bell
A companion piece on the same session, written from a different angle: KOSPI 7,000 Rally Hid More Losers Than Winners.