Arm Holdings: a 4.1σ rise on 21 September 2026
Recorded 7 October 2026On 21 September 2026 Arm Holdings rose 17.16% close to close, 4.1 times its typical daily move of 4.19% over the 20 sessions before it: larger than every one of the 54 sessions on record before it. 28 other instruments of the 198 measured that day moved 2σ or more.
The day
Daily closes, as recorded the night after
- Move
- +17.16%
- Size
- +4.1σ
- Typical day before it
- 4.19%
- Close
- 322.9
- Previous close, 18 September 2026
- 275.61
- Since, to 21 October 2026
- −29.83%
Arm Holdings, the 30 sessions to 21 September 2026
Daily closes; the last point is the quake
Show values
| Point | ARM |
|---|---|
| 7 Aug 2026 | 283 |
| 10 Aug 2026 | 268 |
| 11 Aug 2026 | 269 |
| 12 Aug 2026 | 272 |
| 13 Aug 2026 | 279 |
| 14 Aug 2026 | 279 |
| 17 Aug 2026 | 271 |
| 18 Aug 2026 | 253 |
| 19 Aug 2026 | 249 |
| 20 Aug 2026 | 251 |
| 21 Aug 2026 | 243 |
| 24 Aug 2026 | 239 |
| 25 Aug 2026 | 242 |
| 26 Aug 2026 | 251 |
| 27 Aug 2026 | 255 |
| 28 Aug 2026 | 239 |
| 31 Aug 2026 | 242 |
| 1 Sep 2026 | 235 |
| 2 Sep 2026 | 235 |
| 3 Sep 2026 | 243 |
| 4 Sep 2026 | 252 |
| 8 Sep 2026 | 262 |
| 9 Sep 2026 | 264 |
| 10 Sep 2026 | 254 |
| 11 Sep 2026 | 265 |
| 14 Sep 2026 | 239 |
| 15 Sep 2026 | 242 |
| 16 Sep 2026 | 244 |
| 17 Sep 2026 | 265 |
| 18 Sep 2026 | 276 |
| 21 Sep 2026 | 323 |
The same day
Other quakes on 21 September 2026
| Instrument | Move | Size |
|---|---|---|
| Meta Platforms META | +11.34% | +5.9σ |
| Dogecoin DOGE | +14.14% | +4.2σ |
| Qualcomm QCOM | +9.29% | +3.9σ |
| Novo Nordisk NVO | −7.96% | −3.7σ |
| Intuitive Machines LUNR | +12.93% | +3.5σ |
| Nasdaq 100 NDX | +2.83% | +3.3σ |
| Intel INTC | +12.14% | +3.2σ |
| AMD AMD | +9.95% | +3.1σ |
| Bitcoin BTC | +6.73% | +3.1σ |
| AppLovin APP | +7.18% | +3.0σ |
Arm Holdings's other quakes
On record, newest first
- 4 August 2026: +17.36%, +3.2σ
How it is measured
The move is the close-to-close return; its size is that return divided by the standard deviation of Arm Holdings'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 Arm Holdings'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.