Unusual price movements and significant market activity for Arm Holdings plc American Depositary Shares (ARM). Each move is flagged by Z-score statistical significance — showing when ARM moved beyond its typical daily range. 10 significant moves detected in the last 30 days.
Current Market State
What May Be Driving ARM?
No specific catalyst has been identified in the available market data for Arm Holdings plc American Depositary Shares (ARM). The moves shown below are flagged based on statistical significance (Z-score ≥ 2), meaning ARM moved beyond its typical daily range. A catalyst may exist — such as earnings, analyst action, sector momentum, or news — but has not yet been tagged to this ticker.
Arm Holdings plc American Depositary Shares operates in the Other sector. Sector-wide movement can contribute to individual stock volatility.
Recent Unusual Moves (30 days)
| Date | Session | Price | Move | Z-Score | Rel. Vol. |
|---|---|---|---|---|---|
| Aug 26, 2026 | Regular | $251.85 | +4.26% | 2.84 | — |
| Aug 18, 2026 | Pre-market | $258.62 | -4.72% | -3.15 | — |
| Aug 12, 2026 | Pre-market | $277.62 | +3.23% | 2.16 | — |
| Aug 7, 2026 | Pre-market | $296.85 | +3.55% | 2.37 | — |
| Aug 6, 2026 | Regular | $287.87 | +4.84% | 3.23 | — |
| Aug 6, 2026 | After-hours | $288.84 | +5.20% | 3.46 | — |
| Aug 4, 2026 | Pre-market | $252.95 | +5.81% | 3.87 | — |
| Aug 4, 2026 | Regular | $281.76 | +17.86% | 11.91 | — |
| Aug 4, 2026 | After-hours | $274.91 | +15.00% | 10.00 | — |
| Aug 3, 2026 | Pre-market | $231.51 | -3.41% | -2.28 | — |
About ARM Market Moves
This page tracks unusual market activity for Arm Holdings plc American Depositary Shares (ARM) across all trading sessions — pre-market (4:00 AM–9:30 AM ET), regular hours (9:30 AM–4:00 PM ET), and after-hours (4:00 PM–8:00 PM ET). A move is flagged as "unusual" when its Z-score reaches 2 or higher, meaning the price change is statistically significant relative to ARM's recent daily volatility.
Z-score is calculated by comparing each move to the 20-day average return and standard deviation. A Z-score of 2.0 means the move is 2 standard deviations beyond the average — occurring in roughly the top 5% of daily moves. Relative volume (RVOL) compares current volume to the 20-day average volume at the same time of day, helping distinguish genuine institutional activity from noise.