+1 sessions
Median return +0.48%Completed observations: 13
- Middle 50%
- -1.66% … +1.10%
- Positive returns
- 62%
Salesforce · Sigma Moves
Closed-period price moves, measured against their own history. One engine. Five markets. No forecasts.
Latest closed period
Salesforce's latest move against its own history.
CRM Rare
-8.27%
-2.73σ
About once every 48 trading sessions
26 comparable moves / 1,258 observations
What happened afterwards
All history-qualified moves of at least 2.5σ. Results after the event are descriptive statistics, not trading instructions.
+7 sessions
Median return -0.84%Completed observations: 13
- Middle 50%
- -7.33% … +1.35%
- Positive returns
- 46%
+30 sessions
Median return -4.94%Completed observations: 13
- Middle 50%
- -13.05% … +1.00%
- Positive returns
- 38%
Every rare move, in context
Instrument: CRM (price return)
| Date | σ | Move | Observed rarity | +1 sessions | +7 sessions | +30 sessions |
|---|---|---|---|---|---|---|
| 1 Dec 2022 | -2.73σ | -8.27% | About once every 48 trading sessions26 comparable moves / 1,258 observations | -1.66% | -9.45% | +1.00% |
| 10 Nov 2022 | +3.33σ | +10.02% | About once every 90 trading sessions14 comparable moves / 1,258 observations | +0.91% | -7.33% | -17.18% |
| 2 Nov 2022 | -2.76σ | -6.14% | About once every 48 trading sessions26 comparable moves / 1,258 observations | -2.45% | +5.15% | -13.05% |
| 1 Jun 2022 | +3.37σ | +9.88% | About once every 98 trading sessions12 comparable moves / 1,172 observations | +7.00% | +1.35% | -4.94% |
| 5 Jan 2022 | -3.77σ | -8.28% | About once every 153 trading sessions7 comparable moves / 1,071 observations | +0.65% | +1.56% | -12.14% |
| 1 Dec 2021 | -6.64σ | -11.74% | 1 times in 4 years1 comparable moves / 1,047 observations | +3.86% | +5.78% | -9.09% |
| 29 Nov 2021 | +3.30σ | +4.41% | About once every 95 trading sessions11 comparable moves / 1,045 observations | -3.97% | -10.25% | -20.86% |
| 10 Nov 2021 | -2.85σ | -3.24% | About once every 57 trading sessions18 comparable moves / 1,033 observations | +1.10% | +0.50% | -15.53% |
| 23 Sep 2021 | +6.49σ | +7.21% | 1 times in 4 years1 comparable moves / 999 observations | +2.80% | -2.52% | +10.86% |
| 28 May 2021 | +3.33σ | +5.43% | About once every 102 trading sessions9 comparable moves / 918 observations | -0.80% | -0.84% | +2.49% |
| 26 Feb 2021 | -3.57σ | -6.31% | About once every 171 trading sessions5 comparable moves / 854 observations | +0.48% | -2.30% | +5.66% |
| 25 Feb 2021 | -2.50σ | -3.90% | About once every 36 trading sessions24 comparable moves / 853 observations | -6.31% | -10.11% | +0.09% |
| 2 Dec 2020 | -3.55σ | -8.52% | About once every 159 trading sessions5 comparable moves / 796 observations | +0.09% | +0.74% | -3.46% |
The number has a method behind it
Sigma measures the size of a log return relative to volatility estimated before the period. Rarity is counted from actual historical standardized moves, not inferred from a normal distribution.
σt = ln(Ct / Ct−1) / vtvt ← t−1, t−2, …
Volatility adapts to the market regime with EWMA (λ = 0.94 for daily and weekly observations). Current-period returns are excluded. Each historical σ uses its own prior volatility.
Both directions count toward rarity. Reference history spans up to five years. A period with no prior exceedances is labelled unprecedented in the observed sample; it is never given an invented recurrence interval.
Stock observations use split-adjusted price returns, without dividend reinvestment. Commodities are explicitly labelled ETF price proxies; they do not represent spot commodity prices.
Questions behind the sigma
What does a 3σ move mean?
The period log return is three times the volatility estimated from earlier periods. Sigma is signed: negative for declines and positive for rises.
Why not calculate rarity from a normal distribution?
Market returns have heavy tails and changing volatility. We count actual past absolute sigma exceedances for the same instrument and period.
Does “once every 200 days” predict the next event?
No. It is the number of historical observed periods divided by comparable moves. Events can cluster and the market regime can change.
How much history is required?
At least three years of valid standardized observations, after a one-year volatility warm-up. This normally requires approximately four years of source history.
Are all instruments directly comparable?
The engine is shared, but each instrument has its own prices, calendar, volatility and reference sample. Commodity cards use explicitly labelled ETF proxies.
What happens on quiet days?
The page shows the largest covered standardized move, the complete rarity scale and recent records. Missing data is reported separately from market calm.
For information only. Historical observations are not investment advice and do not predict future moves. A rare move can be followed by another rare move.