Costco: a 3.4σ fall on 9 July 2026
Recorded 7 October 2026On 9 July 2026 Costco fell 4.21% close to close, 3.4 times its typical daily move of 1.24% over the 20 sessions before it: larger than every one of the 3 sessions on record before it. 12 other instruments of the 199 measured that day moved 2σ or more.
The day
Daily closes, as recorded the night after
- Move
- −4.21%
- Size
- −3.4σ
- Typical day before it
- 1.24%
- Close
- 912.97
- Previous close, 8 July 2026
- 953.13
- Since, to 21 October 2026
- +9.35%
Costco, the 19 sessions to 9 July 2026
Daily closes; the last point is the quake
Show values
| Point | COST |
|---|---|
| 10 Jun 2026 | 983 |
| 11 Jun 2026 | 976 |
| 12 Jun 2026 | 982 |
| 15 Jun 2026 | 979 |
| 16 Jun 2026 | 987 |
| 17 Jun 2026 | 966 |
| 18 Jun 2026 | 951 |
| 22 Jun 2026 | 951 |
| 23 Jun 2026 | 958 |
| 24 Jun 2026 | 961 |
| 25 Jun 2026 | 942 |
| 26 Jun 2026 | 953 |
| 29 Jun 2026 | 947 |
| 30 Jun 2026 | 935 |
| 1 Jul 2026 | 925 |
| 2 Jul 2026 | 952 |
| 6 Jul 2026 | 950 |
| 7 Jul 2026 | 948 |
| 8 Jul 2026 | 953 |
| 9 Jul 2026 | 913 |
The same day
Other quakes on 9 July 2026
| Instrument | Move | Size |
|---|---|---|
| Euro / Polish Zloty EUR/PLN | +0.58% | +3.3σ |
| US Dollar / Colombian Peso USD/COP | −1.46% | −3.1σ |
| US Dollar / Turkish Lira USD/TRY | +0.17% | +3.0σ |
Costco's other quakes
On record, newest first
- 14 October 2026: +2.87%, +3.1σ
- 25 September 2026: +2.93%, +3.1σ
How it is measured
The move is the close-to-close return; its size is that return divided by the standard deviation of Costco's previous 20 daily returns. A quake is 3σ or more. This record was made the night after the day finished trading and has not been changed since. The live chart is on Costco's page; the last few months of every market's daily moves are on the volatility terrain, and every quake on record is in the quake archive.