KOSPI closes at 6,687.21 on September 4, 2026 — retail sold 3.7 trillion won and it rose anyway
The KOSPI closed at 6,687.21 on September 4, 2026, up 107.73 points or 1.64 percent, its second straight gain after the 3.99 percent fall of September 2. The KOSDAQ rose 23.29 points or 2.95 percent to 813.50, taking back the 800 level within a day. The notable feature was the flow rather than the level. Individual investors sold a net 3.72 trillion won and the index rose anyway, because institutions bought 1.67 trillion, other corporations 1.57 trillion and foreign investors roughly 0.5 trillion, a combined figure that matched the retail selling almost exactly. Samsung Electronics rose 2.20 percent to 255,500 won and SK hynix 3.20 percent to 1,647,000 won, and large caps gained 1.76 percent while mid caps managed 0.09 percent. The won firmed 8.9 won to 1,350.4 per dollar, its strongest in fourteen months. The premise of the rally was overturned that same evening by the US August jobs report
The three lines
- Close — KOSPI 6,687.21 (+107.73pt, +1.64%); KOSDAQ 813.50 (+2.95%), back above 800
- Flow — retail sold a net 3.72tn won; institutions, corporates and foreigners absorbed 3.75tn
- Reversal — the rate-pause premise behind the rally was undone by US payrolls that night
Key questions
- What was the KOSPI close on September 4, 2026?
- **The index closed at 6,687.21**, up **107.73 points or 1.64 percent**. The intraday high was **6,746.14**, and the low of **6,654.36** was also the open — the index spent the entire session above the previous close. Alongside it: the **KOSDAQ closed at 813.50** (+23.29 points, +2.95 percent), recovering the 800 level it had surrendered a day earlier, on turnover of 6.65 trillion won. The **won closed at 1,350.4 per dollar**, 8.9 won stronger and reported as a fourteen-month high for the currency. By size band, **large caps rose 1.76 percent, small caps 0.71 percent and mid caps 0.09 percent** — the gain was concentrated at the top. Set against the 273-point (3.99 percent) collapse of September 2, two sessions of rebound have recovered roughly 124 points.
- How did the index rise while retail investors sold 3.7 trillion won?
- **Because the other three investor categories absorbed almost exactly that amount.** Net flows on the main board were: individuals **−3.72 trillion won**, institutions **+1.669 trillion**, other corporations **+1.574 trillion**, foreign investors **+0.503 trillion**. The three buyers total **3.747 trillion won** against retail selling of 3.722 trillion — a gap of about 24 billion won. That arithmetic is the day's explanation. The categories are not equivalent. **Other corporations at 1.574 trillion won** is the line that captures company buybacks, and Samsung Electronics (15 trillion won through November 21) and SK hynix (40 trillion won through November 19) are both running programmes. That line has now printed above 1.5 trillion won for three consecutive sessions — 1.650 trillion on September 2, 1.610 trillion on September 3, 1.574 trillion on September 4. **Retail's 3.72 trillion of selling** reads as an unwind: individuals bought a net 2.30 trillion won into the September 2 crash and have sold on both rebound days since.
- Will the rally continue?
- **The first thing to note is that the premise underneath it collapsed the same evening.** Korean shares rose on September 4 because US markets had risen overnight, and US markets had risen because Fed Governor Christopher Waller said on September 3 that the September decision depended on the August inflation print, which pushed implied hike odds down. Then at **21:30 Korean time on September 4** — six hours after the Seoul close — the US August employment report showed nonfarm payrolls up **162,000** against forecasts near 55,000, with July revised from −23,000 to +21,000. Hike odds rose again, and the **S&P 500 closed 0.38 percent lower at 7,718.60** with the 2-year Treasury yield at its highest since January 2025 (see "US August payrolls 162,000"). **The rally's premise and that night's data point in opposite directions.** The counterweight is that the gain was led by semiconductor large caps, whose drivers — buyback flows and the US chip tariff negotiation — sit outside the rate story. Which of the two dominates the next session is not established.
The KOSPI closed at 6,687.21 on September 4, up 107.73 points or 1.64 percent — a second consecutive gain after the 273-point (3.99 percent) collapse of September 2.
The KOSDAQ did better still, rising 23.29 points or 2.95 percent to 813.50, recovering within one session the 800 level it had lost the day before.
On the levels alone this is an unremarkable rebound. What is worth reading is who bought and who sold, and what the rally assumed.
1. The 3.72 trillion won that changed hands
Individual investors sold a net 3.72 trillion won on the main board — the heaviest single retail selling day of this stretch. The index rose 1.64 percent regardless.
Adding up the other side explains why.
| Category | September 4 net | Character |
|---|---|---|
| Individuals | −3.722tn won | Unwinding the crash-day buy |
| Institutions | +1.669tn won | Pensions, securities firms' books |
| Other corporations | +1.574tn won | The line that captures buybacks |
| Foreign investors | +0.503tn won | 479.3bn–503.4bn by outlet |
| Three buyers combined | +3.747tn won | 24bn won more than retail sold |
The buying side matches the selling side almost exactly. That is the arithmetic of the day.
The three categories are not the same thing.
Other corporations at 1.574 trillion won is where company share repurchases land. Samsung Electronics is buying up to 15 trillion won of its own stock through November 21 and SK hynix up to 40 trillion won through November 19. The line has printed above 1.5 trillion won for three sessions running — 1.650 trillion, 1.610 trillion, 1.574 trillion. It arrives regardless of sentiment.
Retail's 3.72 trillion of selling is best read as an unwind. Individuals bought a net 2.30 trillion won into the September 2 crash, sold 955 billion on September 3, and sold 3.72 trillion on September 4. They used the two rebound days to take profit.
2. What actually rose
The size bands tell the story:
- Large caps +1.76%
- Small caps +0.71%
- Mid caps +0.09%
The leaders:
- Samsung Electronics 255,500 won (+2.20%)
- SK hynix 1,647,000 won (+3.20%)
Both fell more than 4 percent on September 2, so this is the semiconductor pair pulling the index back two sessions later (see "Samsung Electronics and SK hynix fall 4% on September 2, 2026"). The KOSDAQ's 2.95 percent gain has a similar character — it had fallen furthest.
The won closed at 1,350.4 per dollar, 8.9 won stronger, described by one outlet as a fourteen-month high for the currency. Foreign buying and a firmer won often come together, but at roughly 500 billion won the foreign net purchase is not large enough to account for the move on its own.
3. The premise collapsed that night
The rally's background was an overnight gain on Wall Street, and that gain came from September hike odds falling after Fed Governor Christopher Waller said on September 3 that the decision depended on the August inflation print.
Six hours after the Seoul close — 21:30 Korean time on September 4 — the US August employment report landed.
| Measure | Reported | Forecast |
|---|---|---|
| Nonfarm payrolls | +162,000 | 53,000–56,000 |
| Unemployment rate | 4.1% | 4.1% |
| July revision | −23,000 → +21,000 | — |
Triple the forecast, with July's decline erased. Hike odds went back up, US stocks and short-dated Treasuries sold off together, the S&P 500 closed 0.38 percent lower at 7,718.60, and the 2-year yield reached its highest since January 2025 (see "US August payrolls 162,000").
The assumption behind Seoul's rally and the fact established that evening point in opposite directions. Several Korean outlets attributed the day's gain to expectations of Fed accommodation; the indicator underlying that expectation arrived hours later saying the opposite.
4. What is still open
- The flow figures differ by outlet. Foreign net buying was reported as both 479.3 billion and 503.4 billion won, and retail net selling as 2.5 trillion intraday versus 3.722 trillion at the close. The direction is unanimous; the Korea Exchange final tally settles the amounts.
- Two drivers are pulling opposite ways. Rates (a hot payrolls print raising hike odds) weigh on the index; semiconductors (buyback flow, the US tariff negotiation) support it. Which dominates the next session is not established.
- The US chip tariff is unresolved. A presidential office official said on September 4 that semiconductors are part of the investment discussions with Washington, and Commerce Secretary Howard Lutnick has promised a "targeted, thoughtful tariff policy" (see "US chip tariffs and the Korea talks, September 4, 2026"). Samsung and SK hynix are directly exposed to the outcome.
- The buybacks have end dates — November 21 for Samsung Electronics, November 19 for SK hynix. Those dates bound how long the trillion-won daily bid can keep acting as the index's floor.
Sources
- Asia Economy — KOSPI closes at 6687.48, up 107.73 points (1.64%)
- MoneyToday — KOSPI closes up 107.73 points (1.64%) at 6687.21
- Financial News — Samsung and SK hynix lift KOSPI 1.64% on large-cap strength
- Businesskorea — KOSPI recovers 6,680 level, KOSDAQ surges 3%
- Financial News — KOSPI nears 6700 as chip pair extends gains; retail sells 2.5tn
- Mediawatch — Foreigners and institutions buy together as chips drive the rebound