Correction — 22 October 2026: The original 5.88% KOSPI decline used an incorrect comparison baseline. The adjacent closing observations imply a 0.44% decline. The earlier claim that Korea fell more than twice as much as the Nasdaq is withdrawn.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.
The corrected comparison reverses the relative-performance story
KOSPI moved from 6,035.35 to 6,008.81, a loss of 26.54 index points. That is about 0.44%, not 5.88%. The S&P 500 fell 1.11% and the Nasdaq fell 1.88% in their later US sessions. On these separate daily windows, the US benchmarks fell more in percentage terms than KOSPI.
Dated observations and calculations
| Series / source | Previous date | Previous value | Observation date | Value | Change | Time zone |
|---|---|---|---|---|---|---|
| KOSPI | 2026-10-13 | 6,035.35 | 2026-10-14 | 6,008.81 | -0.44% | Asia/Seoul |
| S&P 500 | 2026-10-13 | 7,805.45 | 2026-10-14 | 7,718.94 | -1.11% | America/New_York |
| Nasdaq Composite | 2026-10-13 | 27,204.38 | 2026-10-14 | 26,692.87 | -1.88% | America/New_York |
| US 10-year yield proxy (^TNX) | 2026-10-13 | 5.217 | 2026-10-14 | 5.190 | -2.7 bp | America/Chicago |
| WTI futures (CL=F) | 2026-10-13 | 94.14 | 2026-10-14 | 95.09 | +1.01% | America/New_York |
| Gold futures (GC=F) | 2026-10-13 | 4,177.30 | 2026-10-14 | 4,107.90 | -1.66% | America/New_York |
A denominator error changes the analysis
The return formula divides the change by the immediately preceding close. Comparing against an older baseline can turn a modest daily loss into a much larger reported move. Any explanation built around an exceptionally large Korean sell-off on this date therefore needs to be discarded. Sector contributions and investor-flow data would be needed to explain the actual decline; the index level supplies neither.
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. 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.
