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British Pound / Japanese Yen · Sigma Moves

Closed-period price moves, measured against their own history. One engine. Five markets. No forecasts.

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Latest closed period

British Pound / Japanese Yen's latest move against its own history.

31 July 2026 · Daily Updated 20:06 UTC
GBPJPY Very rare -1.22% -3.83σ About once every 130 trading sessions 10 comparable moves / 1,295 observations

What happened afterwards

All history-qualified moves of at least 2.5σ. Results after the event are descriptive statistics, not trading instructions.

+1 sessions

Median return +0.02%

Completed observations: 43

Middle 50%
-0.35% … +0.48%
Positive returns
53%

+7 sessions

Median return -0.26%

Completed observations: 43

Middle 50%
-0.57% … +0.72%
Positive returns
44%

+30 sessions

Median return +1.58%

Completed observations: 43

Middle 50%
-0.14% … +3.40%
Positive returns
74%

Every rare move, in context

Instrument: GBPJPY=X (price return)

DateσMoveObserved rarity+1 sessions+7 sessions+30 sessions
31 Jul 2026 -3.83σ -1.22% About once every 130 trading sessions10 comparable moves / 1,295 observations -1.40% -0.27% -3.22%
16 Jul 2026 +2.89σ +0.97% About once every 52 trading sessions25 comparable moves / 1,295 observations -0.26% -0.43% -1.32%
18 Jun 2026 -2.84σ -0.81% About once every 50 trading sessions26 comparable moves / 1,295 observations -0.32% -0.05% +2.19%
1 May 2026 -3.91σ -1.17% About once every 144 trading sessions9 comparable moves / 1,295 observations -0.24% +0.17% +0.58%
11 Feb 2026 -2.90σ -1.40% About once every 52 trading sessions25 comparable moves / 1,295 observations -0.86% -0.84% +1.10%
22 Dec 2025 +3.71σ +1.26% About once every 130 trading sessions10 comparable moves / 1,299 observations +0.17% +0.51% +0.53%
5 Nov 2025 -2.97σ -1.29% About once every 56 trading sessions23 comparable moves / 1,299 observations +0.59% +1.72% +3.93%
29 Oct 2025 -2.69σ -1.09% About once every 45 trading sessions29 comparable moves / 1,299 observations +0.02% -0.25% +3.56%
6 Oct 2025 +5.33σ +1.57% 2 times in 5 years2 comparable moves / 1,299 observations +0.87% +0.58% +1.22%
4 Aug 2025 -4.43σ -1.68% 4 times in 5 years4 comparable moves / 1,299 observations -0.31% +1.90% +2.21%
7 Apr 2025 -3.34σ -1.90% About once every 118 trading sessions11 comparable moves / 1,302 observations +0.24% +0.86% +2.74%
18 Nov 2024 -2.76σ -1.55% About once every 45 trading sessions29 comparable moves / 1,305 observations +0.45% -1.42% +1.76%
30 Sep 2024 -2.64σ -1.78% About once every 40 trading sessions33 comparable moves / 1,305 observations +0.59% +1.52% +3.35%
1 Aug 2024 -2.85σ -1.79% About once every 47 trading sessions28 comparable moves / 1,305 observations -1.33% -2.59% -3.40%
18 Jul 2024 -3.02σ -1.46% About once every 52 trading sessions25 comparable moves / 1,305 observations +0.51% -2.05% -5.90%
12 Jul 2024 -4.46σ -1.57% About once every 261 trading sessions5 comparable moves / 1,305 observations +0.41% -0.76% -6.36%
3 May 2024 -2.79σ -1.69% About once every 47 trading sessions28 comparable moves / 1,305 observations +0.35% +2.25% +4.43%
29 Apr 2024 +3.96σ +1.69% About once every 163 trading sessions8 comparable moves / 1,305 observations -0.80% -2.26% +0.86%
20 Mar 2024 +3.59σ +1.21% About once every 131 trading sessions10 comparable moves / 1,305 observations +0.44% -0.49% +2.54%
8 Dec 2023 -4.16σ -1.74% About once every 186 trading sessions7 comparable moves / 1,304 observations +0.22% -0.58% +3.65%

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.