TL;DR — If you own Korean stocks or a Korea fund. KOSPI alternated up and down across the five sessions from Oct. 19 to Oct. 23 and ended the week down 2.08%, while Samsung Electronics finished exactly flat and SK hynix gained 0.39%. With Korea’s two largest stocks by market value standing still, the arithmetic says the rest of the KOSPI fell more than the index did, and KOSDAQ, the smaller-company index, lost 5.42%.
Your Door — what to check if you hold Korean stocks on the KRX, directly or through a U.S. broker. KOSPI fell 2.08% and KOSDAQ 5.42% over Oct. 19–23 while Samsung Electronics (0.00%) and SK hynix (+0.39%) ended where they started. Compare your own holdings with the index: on Fri., Oct. 23, 719 KOSPI stocks fell and 173 rose. Next week the two report about 25 hours apart: SK hynix on Wed., Oct. 28, 9:00 a.m. Seoul and Samsung Electronics on Thu., Oct. 29, 10:00 a.m. Seoul. EWY rose 0.55% in dollars over the U.S. week (Oct. 19–23, $150.44 to $151.26); the two stocks are 44.68% of the fund (iShares, as of Oct. 21; see what moves EWY). EWY is priced in dollars and KOSPI in won, so we don’t compare their weekly returns directly.
Not financial advice.
Dates and times are Seoul time (KST) unless marked otherwise. Stock and index prices are KRX (Korea Exchange) regular-session closes (15:30 Seoul); the latest is Fri., Oct. 23, 2026. Exchange rates are the Seoul 3:30 p.m. rate reported by Korean outlets. Dollar conversions are for scale only, at ₩1,324.6 per dollar, the Oct. 23 rate. U.S.-listed prices (EWY, SKHY) are U.S. closes on U.S. trading days.
Five sessions in Seoul, Oct. 19 to Oct. 23. The index alternated up and down across all five sessions and closed the week 2.08% lower, from 5,668.05 to 5,550.30. Samsung Electronics, one of its two giants, ended exactly where it started.
The scoreboard, Oct. 19–23
| Session (KST) | KOSPI close | KOSPI daily | KOSDAQ daily |
|---|---|---|---|
| Fri., Oct. 16 (previous week’s last session) | 5,668.05 | — | — |
| Mon., Oct. 19 | 5,768.01 | +1.76% | +1.78% |
| Tue., Oct. 20 | 5,552.74 | −3.73% | −3.33% |
| Wed., Oct. 21 | 5,735.66 | +3.29% | +1.38% |
| Thu., Oct. 22 | 5,533.77 | −3.52% | −3.62% |
| Fri., Oct. 23 | 5,550.30 | +0.30% | −1.62% |
| Week | −2.08% | −5.42% |
| Week in review | Value |
|---|---|
| Samsung Electronics | ₩215,500 → ₩215,500 (about $163), 0.00% |
| SK hynix | ₩1,272,000 → ₩1,277,000 (about $964), +0.39% |
| KOSDAQ (Korea’s smaller-company index) | 794.78 → 751.69, −5.42% |
| Won per dollar, Seoul 3:30 p.m. | ₩1,331.4 → ₩1,324.6, won +0.51% |
| Foreign investors’ net trading (buying minus selling) in KOSPI shares | About −₩0.8 trillion (about $0.6 billion) — our sum of daily figures from Korean outlets; some are preliminary counts |
Source: KRX closes via Yahoo Finance.
Four notes on the week
1. The index alternated up and down every session. Added up without their signs, the five daily moves come to about 12.6 percentage points, for a net result of −2.08%. The gap between the week’s highest close (5,768.01 on Oct. 19) and its lowest (5,533.77 on Oct. 22) was 4.2%. On Friday the index fell as low as 5,305.98 during the session, about 4.1% below Thursday’s close, and then closed up 0.30%.
2. The two giants went nowhere. Samsung Electronics ended the week at exactly 0.00% and SK hynix at +0.39%. Both had large days in between: on Oct. 21 Samsung rose 5.67% and SK hynix 5.81%, and on Oct. 22 they fell 4.03% and 5.49%. By Friday both were back near their starting points, so the week’s −2.08% came from the rest of the index.
Source: KRX closes via Yahoo Finance.
3. The rest of the market was weaker. KOSPI is weighted by market value: the bigger the company, the larger its share of the index. If the two biggest stocks returned roughly zero and the index fell 2.08%, the weighted average of all the other stocks has to be below −2.08% for the arithmetic to work. A few examples: LG Energy Solution −4.96% and Hyundai Motor −5.29%. Some went the other way; Samsung Biologics gained 12.94%. And on Friday, the day KOSPI rose 0.30%, 719 KOSPI stocks fell and 173 rose, with 48 unchanged, according to counts by two Korean outlets, Pinpoint News and License News. Even on the up day, decliners outnumbered gainers about four to one.
4. Foreign selling shrank. Foreign investors’ net trading in KOSPI shares was about −₩38.1 billion on Oct. 19, −₩530 billion on Oct. 20, +₩660 billion on Oct. 21, +₩59.2 billion on Oct. 22 and −₩993.4 billion on Oct. 23. That adds up to roughly −₩0.8 trillion (about $0.6 billion) for the week. These are daily figures from Korean outlets; for Oct. 22 and Oct. 23 the outlets differ slightly, and the counts were taken just after the close. The week before, the total was about −₩11 trillion (see last week’s scoreboard), so this week’s net selling was less than a tenth of that. The won also strengthened a little, by 0.51%.
Under the Gat (our take). “With Samsung Electronics at 0.00% and SK hynix at +0.39% for the week, KOSPI’s −2.08% came from the rest of the market, whose own average fell by more. On Friday, Oct. 23, the index closed up 0.30%, while 719 KOSPI stocks closed lower and 173 higher. If you hold individual Korean names and the week felt worse than the index, that Friday count shows the gap.”
Three dated events from the week
| Date (KST) | Event | How sure |
|---|---|---|
| Mon., Oct. 19 | Korea’s 15% per-stock limit on margin loans at brokerages took effect (see what changed after Oct. 19) | Rule in effect; reported by Korean press and the Korea Financial Investment Association |
| Thu., Oct. 22 | The Bank of Korea held its base rate at 3.00%; all seven board members voted for the hold | Reported by three Korean outlets; the bank’s own statement not yet checked |
| Fri., Oct. 23 | SK hynix said in a filing that it stopped reviewing an IPO of its U.S. subsidiary, Solidigm (see what Seoul said about U.S. IPOs) | Company filing, DART 20261023800002 |
This table lists dates. We found no source showing that these events drove the index this week.
Next week, both giants report within about 25 hours
All three fall between Wednesday morning and Thursday morning, Seoul time.
| Seoul (KST) | U.S. Eastern (ET) | Event |
|---|---|---|
| Wed., Oct. 28, 9:00 a.m. | Tue., Oct. 27, 8:00 p.m. | SK hynix third-quarter results (DART 20261014800385) |
| Thu., Oct. 29, 3:00 a.m. | Wed., Oct. 28, 2:00 p.m. | U.S. Federal Reserve (FOMC) statement |
| Thu., Oct. 29, 10:00 a.m. | Wed., Oct. 28, 9:00 p.m. | Samsung Electronics third-quarter earnings call (DART 20261008800028) |
This week Samsung Electronics and SK hynix ended near their starting points while the rest of the index fell. The calendar makes next week likely to be the reverse: a week in which Samsung Electronics and SK hynix explain most of what the index does. About 45% of EWY (as of Oct. 21) sits in the two stocks reporting in this window.
Under the Gat (our take). “Our first check next week is KOSDAQ, which lost 5.42% this week. If Samsung and SK hynix lift KOSPI with their Oct. 28–29 results while KOSDAQ keeps falling, this week’s reading of a weak rest-of-market still stands.”
Ways into the KOSPI, and the S&P 500 breadth habit
- Ways in: for the whole market, EWY, the U.S.-listed Korea ETF, about 45% of it in the two giants. For individual stocks, KRX shares directly through a U.S. broker that offers Korean stocks, such as Interactive Brokers. SK hynix also trades in the U.S. as SKHY, an ADR (a U.S.-listed certificate that stands for Korean shares), which rose 0.39% over the U.S. week, from $136.49 to $137.02.
- U.S. comparison: American investors often compare two versions of the S&P 500: the market-value-weighted one (SPY) and the equal-weighted one (RSP). When the two diverge, they read it as a sign that breadth, meaning how many stocks take part in a move, is narrow. This week’s KOSPI showed the same split in a different shape: the two largest stocks held still while breadth was weak. Not a perfect parallel: Korea’s concentration sits in two stocks, which makes it simpler and more extreme than the U.S. big-tech group. We do not compare numbers between the two markets here.
The bottom line
KOSPI’s −2.08% for the week of Oct. 19–23 came from the rest of the Korean market while Samsung Electronics (0.00%) and SK hynix (+0.39%) stood still: KOSDAQ fell 5.42%, and on Friday KOSPI decliners outnumbered gainers about four to one. Next week those two companies report, on Oct. 28 and Oct. 29.
FAQ
KOSPI only fell about 2% this week. Why did my Korean stocks fall more?
This week the two largest stocks in the index, Samsung Electronics and SK hynix, were almost unchanged. When those two stand still, the index reflects the other stocks, and by our arithmetic those fell more than the index’s 2.08%. KOSDAQ lost 5.42%.
Why did EWY rise when KOSPI fell?
EWY trades in dollars on U.S. trading days; its U.S. close went from $150.44 on Oct. 16 to $151.26 on Oct. 23, up 0.55%. The won strengthened 0.51% that week, and about 45% of EWY is in two stocks that ended roughly flat. We did not find a single cause in the data we checked. EWY is priced in dollars and KOSPI in won, so we do not subtract one return from the other.
What are the key dates next week?
SK hynix results at 9:00 a.m. Seoul on Wed., Oct. 28; the Federal Reserve statement at 3:00 a.m. Seoul on Thu., Oct. 29; and Samsung Electronics’ earnings call at 10:00 a.m. Seoul on Thu., Oct. 29. In U.S. Eastern time, that runs from Tuesday evening, Oct. 27, to Wednesday evening, Oct. 28.
Sources
- KRX closes for KOSPI, KOSDAQ and individual stocks: Yahoo Finance chart data (^KS11, ^KQ11, 005930.KS, 000660.KS, 373220.KS, 005380.KS, 207940.KS; vendor data), retrieved Oct. 25, 2026.
- EWY and SKHY: Yahoo Finance chart data, U.S. trading-day closes.
- EWY holdings: iShares MSCI South Korea ETF holdings file, as of Oct. 21, 2026.
- KOSPI advancing and declining issues, Oct. 23: Pinpoint News and License News, Oct. 23 (press).
- Foreign investors’ net trading: License News (Oct. 19, Oct. 21, Oct. 23), Money Today (Oct. 20), Field News (Oct. 21), BusinessKorea (Oct. 22) (press).
- Won-dollar rate at the Seoul 3:30 p.m. close: Asia Economy and Financial News, each date (press).
- Bank of Korea decision, Oct. 22: Media Watch, Aju Business Daily, Korea JoongAng Daily (press; the bank’s decision statement not yet checked).
- SK hynix Solidigm filing: DART 20261023800002.
- Results schedules: SK hynix, DART 20261014800385; Samsung Electronics, DART 20261008800028.
How sure are we?
| Item | Confidence |
|---|---|
| KOSPI, KOSDAQ and stock closes, daily and weekly changes | ✅ Vendor price data (Yahoo), cross-checked against our daily records for each session |
| Rest of the KOSPI fell more than the index | Our arithmetic from a market-value-weighted index; we do not state the two giants’ exact index weight |
| Friday’s intraday low of 5,305.98 | Intraday level, not a close; vendor data matched by one Korean outlet |
| 719 decliners, 173 gainers, 48 unchanged on Oct. 23 | ⚠️ Press-reported, two outlets agree |
| Foreign net selling of about ₩0.8 trillion | ⚠️ Our sum of press-reported daily figures; Oct. 22–23 differ slightly by outlet and are preliminary |
| Won-dollar 3:30 p.m. rates | ⚠️ Press-reported; dollar conversions our calculation |
| Bank of Korea hold at 3.00%, 7–0 | ⚠️ Press-reported, three outlets; decision statement not yet checked |
| EWY two-stock weight 44.68% | ✅ iShares holdings file, as of Oct. 21 |
| Next week’s results dates | ✅ Company notices on DART |
Not financial advice. TheGatBull is an independent publication; nothing here is a recommendation to buy or sell any security.
Written by Mr.Gat — TheGatBull
Korean market coverage from a Seoul-metro-based operator with 15 years of personal investing experience, who reads the filings in the original language. Every price on this site is the KRX regular-session close (15:30 Seoul); every figure states whether it came from a primary filing, the press, or our own calculation. Drafts are AI-assisted, then verified against the original Korean documents and edited by a human before publishing.
Found an error? Tell us — corrections get priority. How we work →