Not financial advice. TheGatBull does not provide investment advice.
The short answer
On Monday, September 7, US markets were shut for Labor Day. Seoul was open — and it ran. The KOSPI jumped +4.61% to 6,995.39 while your EWY sat frozen at Friday’s close of $188.87. On Tuesday, September 8, Seoul caught its breath and slipped −0.58% to 6,954.52 (it touched the 7,170s intraday before fading — that is an intraday figure, not the close). Then, Tuesday night, New York finally reopened. This was the session that had to price in two Seoul days at once — a cumulative move of roughly +4.0%. The result? EWY +0.55%, to $189.91.
You waited for 4% and got half a percent. Where did it go? To Friday. Last Friday (September 4, a US trading day), EWY had already risen +4.60% and SK Hynix’s US-listed shares (its ADR) had risen +8.14% — before Seoul’s Monday surge ever happened. New York did not wait for Seoul’s Monday. It set the price on Friday. Seoul’s +4.61% was the confirmation, not the news.
What this means for EWY holders
1. If you were waiting to trade “the gap the morning after a US holiday” — that gap is usually pre-paid on the last trading day before the holiday. This week was a clean measurement of it (Friday +4.60% vs. Tuesday +0.55%). 2. The same structure is coming back, reversed: during the Chuseok holiday, Korea’s regular session is closed on Sept 24, 25, and the Sept 28 substitute holiday — three sessions where Seoul sleeps and only EWY trades in New York. Then New York sets the price first, and Seoul receives the receipt.
What happened in Seoul on Tuesday
The KOSPI closed September 8 at 6,954.52, down 0.58%. The open was strong — a semiconductor tailwind pushed the index above 7,000 and toward a run at the 7,170s, with foreign and institutional investors both net buyers early and the won steady in the 1,340s. Through the afternoon, renewed geopolitical risk and firmer oil handed the gains back (a “strong open, weak close” session, as the local press put it). One report noted an intraday print in the 7,170s — but that is an intraday number. On a closing basis, this was a −0.58% breather after Monday’s +4.61% surge. The KOSDAQ closed at 811.88 (−1.25%). USD/KRW settled at 1,345.6, up 5.1 won — the won’s first weakening in five sessions.
The asymmetry, measured — four days in one table
| Day | Seoul (KRX close) | New York (US trading day) |
|---|---|---|
| Fri 9/4 | KOSPI +1.64% | EWY +4.60% · SKHY +8.14% ← pre-priced |
| Mon 9/7 | KOSPI +4.61% | Closed (Labor Day) |
| Tue 9/8 | KOSPI −0.58% | EWY +0.55% ($189.91) · SKHY +4.83% |
How to read it: Friday’s +4.60% in New York cannot be explained by Seoul’s Friday alone (+1.64%). New York was buying the semiconductor optimism ahead of time, and Seoul’s Monday +4.61% confirmed that bet. And remember what EWY actually holds — two big memory names — so SK Hynix’s Friday +8.14% did much of the pulling on the whole fund. So when New York reopened on Tuesday, the bill left to pay was small: most of Seoul’s two-day +4.0% was already in the price, and Tuesday’s Seoul dip (−0.58%) plus a weaker won (+5.1) offset the rest, settling at +0.55%.
One caution on the arithmetic: Seoul’s percentages and New York’s percentages are in different currencies — read them side by side, but do not subtract one from the other. EWY is priced in dollars, so a move in the won changes your EWY number even when Korean stock prices sit still. The exchange rate is baked into the return.
Why this is structure, not luck — and who’s next
This is not a fluke of one week. It is the standing structure of a time-zoned market. Seoul (09:00–15:30 KST) and New York (roughly 22:30–05:00 KST) never overlap for a single minute. So a large part of what looks like “the later market’s opening gap” is really “the earlier market’s last session” — a price that was already made. Our Saturday piece on the won and Sunday’s scoreboard both flagged these two days in advance; today is the result data. And if you want the general version of this idea, it is the same one behind Korea trading Nvidia’s earnings before the US does.
The next turn runs the other way. Because of the Chuseok holiday, the KRX regular session is closed on Thursday 9/24, Friday 9/25, and the Monday 9/28 substitute holiday — three sessions — while EWY and SKHY keep trading in New York. For those three days, New York makes the price, and Seoul’s first session back (September 29) settles all of it at once. It is the mirror image of this Labor Day week. When that week comes, pull this table back out.
What to watch this week (9/9–9/12)
- Approach to the Sept 15–16 FOMC. Hike odds eased late last week; the decision lands Wednesday afternoon ET, which Seoul receives Thursday morning its time.
- KRX trading-hours overhaul begins Monday 9/14. Korea becomes a 12-hour trading market — we cover it in detail in Wednesday’s piece.
- Buyback tracker. Whether Korean companies keep buying back their own shares day to day — the metric from Sunday’s scoreboard.
- The won. Whether Tuesday’s turn to weakness (1,345.6) is a one-day move or an FOMC-week trend.
- Chuseok D-window. Seoul is dark on 9/24, 25 and 28 — only EWY and SKHY trade in New York during it.
🎩 Under the Gat — If you were waiting for the gap, the gap already passed on Friday. In a time-zoned market, whoever opens first makes the price, and whoever opens later gets the receipt. During Chuseok week (Seoul closed 9/24, 25, 28), your EWY becomes the one that “opens first” — and that time, Seoul gets the receipt. A view, not advice.
The takeaway
On the Monday the US was shut, Seoul ran 4.6% — and New York’s bill came to half a percent, because the rest had been pre-paid on Friday. The same structure comes back, direction reversed, at Chuseok. The lesson for an EWY holder is not “watch for the holiday gap.” It is: in a market that never overlaps with yours, the price is usually made before your session opens. The gap is a receipt, not a surprise.
FAQ
If Seoul surges while the US is closed, does EWY jump by the same amount the next day?
No — as this week showed, the last US trading day before the holiday tends to pre-price much of it (Friday +4.60% vs. Tuesday +0.55%). The premise behind “trading the holiday gap” is easy to get wrong.
Why is EWY’s +0.55% so different from Seoul’s two-day +4.0%?
Three things net out: (1) Friday’s pre-pricing, (2) Seoul’s −0.58% on Tuesday, and (3) a weaker won (+5.1). An ETF’s dollar return contains both the index and the exchange rate.
What happens during the Chuseok holiday?
The KRX regular session is closed on Sept 24, 25 and the Sept 28 substitute holiday — three sessions — while EWY and SKHY keep trading in New York. Seoul’s first session back (Sept 29) settles all three at once. It is the mirror image of this week’s structure, and we will cover it in its own piece.
Sources
- MoneyToday spot report, 2026-09-08 — KOSPI close 6,954.52 (−0.58%), intraday high in the 7,170s, “strong open, weak close”
- Businesskorea, 2026-09-08 — open (foreign + institutional net buying, won in the 1,340s) and close (geopolitical/oil fade); USD/KRW 1,345.6
- Yahoo Finance v8 chart (sourced 2026-09-09): EWY, SKHY, ^KQ11 daily closes — EWY $188.87 (9/4) → $189.91 (9/8); SKHY $177.00 → $185.55; KOSDAQ 811.88
- KRX holiday calendar — Chuseok regular-session closures Sept 24, 25 and substitute holiday Sept 28
- TheGatBull: WP680 (won), WP687 (scoreboard), WP545 (Korea trades Nvidia before the US), EWY concentration pillar
Not financial advice. This article is for information only. TheGatBull and its author hold no position in the securities mentioned unless disclosed. Confidence labels are as of publication.