Correction — 22 October 2026: The original 4.54% KOSPI decline is corrected to 2.62%. The older mixed-time US and commodity quotes are replaced with dated daily observations. Unsupported links to news headlines and a China-crisis analogy are withdrawn. This is a retrospective review using daily history retrieved on 2026-10-22, not a live report or a reconstruction of every quote available at original publication.
Measure the relative decline before explaining it
KOSPI fell 2.62%, the S&P 500 fell 0.47%, and the Nasdaq fell 1.25% in their respective daily sessions. The Korean decline was about 1.37 percentage points larger than the Nasdaq decline. These are separate local closing windows: the calculation describes relative performance but is not a synchronized response to one event.
Dated observations and calculations
| Series / source | Previous date | Previous value | Observation date | Value | Change | Time zone |
|---|---|---|---|---|---|---|
| KOSPI | 2026-10-07 | 6,803.90 | 2026-10-08 | 6,625.93 | -2.62% | Asia/Seoul |
| S&P 500 | 2026-10-07 | 7,801.77 | 2026-10-08 | 7,765.36 | -0.47% | America/New_York |
| Nasdaq Composite | 2026-10-07 | 27,538.69 | 2026-10-08 | 27,193.34 | -1.25% | America/New_York |
| US 10-year yield proxy (^TNX) | 2026-10-07 | 5.277 | 2026-10-08 | 5.231 | -4.6 bp | America/Chicago |
| WTI futures (CL=F) | 2026-10-07 | 88.28 | 2026-10-08 | 91.49 | +3.64% | America/New_York |
| Gold futures (GC=F) | 2026-10-07 | 4,140.70 | 2026-10-08 | 4,157.00 | +0.39% | America/New_York |
| USD/KRW (won per dollar) | 2026-10-07 | 1,339.74 | 2026-10-08 | 1,339.08 | -0.05% | Europe/London |
| USD/JPY (yen per dollar) | 2026-10-07 | 158.30 | 2026-10-08 | 158.06 | -0.15% | Europe/London |
A rising oil quote does not measure the earnings impact
WTI rose 3.64% while the 10-year yield observation fell by 4.6 basis points. An energy-cost explanation for Korean stocks would still require evidence about company exposures, sector contributions and timing. The daily price series does not establish that oil caused the index decline. Nor does a Korean index move alone establish contagion in China or other emerging markets.
Method and limits
Percentage changes use (value ÷ previous available daily value − 1) × 100, before rounding. Yield changes use the difference in percentage-point quotes multiplied by 100 to obtain basis points. Currency values are local-currency units per US dollar. Index levels are in points; futures quotes are in US dollars per barrel for WTI and per troy ounce for gold.
Each linked Yahoo Finance history is the data source for that row. These provider observations have not been independently checked against exchange settlement records. The futures series can change its referenced contract over time and should not be treated as the return on a continuously held investment. A date shared by two markets does not make their closing times simultaneous.
The earlier news-based explanations are omitted because their relevance to these measured moves was not established. For the calculation workflow and trading-session examples, see How to Read Daily Market Returns Without Mixing Trading Sessions.
