The KOSPI was basically flat this week, but my Korea ETF dropped almost 4%. Did the exchange rate eat it all?
2026-W38
The math behind KOSPI's -0.23% becoming -3.93% in dollars
Almost the entire gap is the exchange rate. The won weakened from 1,348.17 to 1,385.00 per dollar (+2.73%) in a single week, and the Korea ETF EWY fell -3.93%. When the won weakens 5%, EWY's dollar return takes roughly a 5% hit even if the underlying share prices don't move at all (BitMEX, EWY trader guide). What stings more is that the KOSPI itself jumped +2.66% on September 18 alone — and dollar-based investors saw even that rebound eaten by the currency.
Why this week hurt more: the consensus had called it the other way
Just a month ago, the mood was the exact opposite. When USD/KRW fell below 1,400 on August 20, domestic commentary framed it as "a catalyst for foreign inflows into Korean equities" (Edaily, 2026-08-20), with some forecasting a further drop to 1,350 by year-end (Financial News, 2026-08-20). The logic rested on Samsung Electronics and SK Hynix converting dollars for shareholder returns, propping up the won.
But overseas institutions saw it the opposite way. The three-month average forecast from 12 major global investment banks stood at 1,440 won per dollar, with the most optimistic, HSBC, at 1,400, and Nomura and Standard Chartered at 1,460 (Korea Herald, 2026). The root of won weakness they cite isn't the trade balance but the capital account. With Korean retail investors net-buying $51 billion worth of overseas securities in 2025 alone, dollars keep flowing out regardless of how strong chip exports look (Korea Herald, 2026).
This exact gap between the bullish domestic view and the bearish overseas view is the real risk for EWY holders. This week, the overseas view clawed back 37 won in a single week.
The signal flagged this before the KOSPI headline did
| Date | EWY close | 10-day MA | 50-day MA | 150-day MA | Entry condition | Stop-loss buffer | Off high |
|---|---|---|---|---|---|---|---|
| 09-11 | 188.72 | 183.73 | 173.94 | 164.76 | Met | 5.44% | -14.56% |
| 09-14 | 176.22 | 183.34 | 173.86 | 165.10 | Not met | -0.22% | -20.22% |
| 09-15 | 176.49 | 182.90 | 173.59 | 165.44 | Not met | -0.10% | -20.10% |
| 09-16 | 175.54 | 182.87 | 173.48 | 165.78 | Not met | -0.53% | -20.53% |
| 09-17 | 182.39 | 183.23 | 173.47 | 166.12 | Not met | 2.57% | -17.43% |
| 09-18 | 181.31 | 183.30 | 173.40 | 166.46 | Not met | 2.08% | -17.92% |
The stop-loss buffer broke from 5.44% to -0.22% in a single Monday session, and even as the KOSPI rose two straight days late in the week, EWY's close never made it back above its 10-day MA (183.30). This table is the mechanical explanation for "the KOSPI chart recovered but my ETF chart didn't" — the currency clawed back every gain the shares delivered.
Who wins and who loses
| Holding structure | Weekly performance | Why |
|---|---|---|
| KOSPI held directly in a won account | -0.23% | No currency effect |
| EWY held in a dollar account | -3.93% | Full won-weakness impact |
| Won converted to dollars to buy EWY | Close to direct KOSPI holding | Conversion at buy and sell offsets each other |
| Exporters benefiting from won weakness | Relative outperformance | Dollar revenue converts to more won |
The most common misconception needs addressing here. An investor who converted won to dollars specifically to buy EWY experiences a return close to holding the KOSPI directly, because the conversion at entry and exit offsets. The investor who fully feels the -3.93% is the one whose base currency is the dollar. Missing this distinction can lead you to dump a perfectly fine position for the wrong reason.
The currency-hedged escape route has also narrowed. HEWY, the flagship currency-hedged Korea ETF, was delisted on February 26, 2026 (ETF Database, 2026), and the remaining alternatives are thinly traded. Advice to "just switch to a hedged product" isn't very actionable in today's market.
What should investors do
- Investors measuring returns in dollars: EWY's entry condition is unmet with only a 2.08% stop-loss buffer. If USD/KRW re-enters 1,400, it breaks again just like September 14. A new entry only makes sense once USD/KRW falls back below 1,360 and EWY's close returns above its 10-day MA — both conditions together.
- Investors holding Korean equities directly in a won account: This week's -3.93% is not your loss. -0.23% is your number.
- A shared indicator to watch: whether the September 18 foreign net-buying turn proves to be a one-day event. If the currency climbs back into the 1,400s, foreign buying will struggle to continue, and the gap between the KOSPI rebound and EWY performance would simply repeat next week.
Detailed charts and signals for other tickers are available on the /signals dashboard.