Costco: a 3.1σ rise on 25 September 2026
Recorded 7 October 2026On 25 September 2026 Costco rose 2.93% close to close, 3.1 times its typical daily move of 0.95% over the 20 sessions before it: its largest move since 9 July 2026. 1 other instrument of the 146 measured that day moved 2σ or more.
The day
Daily closes, as recorded the night after
- Move
- +2.93%
- Size
- +3.1σ
- Typical day before it
- 0.95%
- Close
- 922.77
- Previous close, 24 September 2026
- 896.48
- Since, to 21 October 2026
- +8.19%
Costco, the 30 sessions to 25 September 2026
Daily closes; the last point is the quake
Show values
| Point | COST |
|---|---|
| 13 Aug 2026 | 962 |
| 14 Aug 2026 | 961 |
| 17 Aug 2026 | 954 |
| 18 Aug 2026 | 961 |
| 19 Aug 2026 | 957 |
| 20 Aug 2026 | 934 |
| 21 Aug 2026 | 948 |
| 24 Aug 2026 | 971 |
| 25 Aug 2026 | 960 |
| 26 Aug 2026 | 956 |
| 27 Aug 2026 | 935 |
| 28 Aug 2026 | 945 |
| 31 Aug 2026 | 944 |
| 1 Sep 2026 | 940 |
| 2 Sep 2026 | 928 |
| 3 Sep 2026 | 925 |
| 4 Sep 2026 | 916 |
| 8 Sep 2026 | 910 |
| 9 Sep 2026 | 903 |
| 10 Sep 2026 | 902 |
| 11 Sep 2026 | 905 |
| 14 Sep 2026 | 919 |
| 15 Sep 2026 | 901 |
| 16 Sep 2026 | 894 |
| 17 Sep 2026 | 894 |
| 18 Sep 2026 | 895 |
| 21 Sep 2026 | 898 |
| 22 Sep 2026 | 899 |
| 23 Sep 2026 | 905 |
| 24 Sep 2026 | 896 |
| 25 Sep 2026 | 923 |
The same day
Other quakes on 25 September 2026
No other instrument moved 3σ or more that day: this one moved on its own.
Costco's other quakes
On record, newest first
- 14 October 2026: +2.87%, +3.1σ
- 9 July 2026: −4.21%, −3.4σ
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.