The Volatility You Measured in London Is Gone by the Time Tokyo Opens
Your ATR is a number. It is sitting on your chart right now, sizing your stop or setting the width of your bands. It looks like a property of the instrument — a fact about how much this pair moves.
It is not that. It is a number computed over a specific set of bars, generated by whichever session was open while those bars printed. And if you trade around the Tokyo open, there is a real chance that number was generated somewhere else entirely — in a session that closed hours ago.
01 FX does not have one market. It has a relay.
There is no single “forex market” the way there is a single New York Stock Exchange. Currency trading runs through overlapping financial centres, handing volume to each other as the earth turns, and the handoff is not close to even.
The Bank for International Settlements runs the authoritative measure of this — the Triennial Central Bank Survey, the most comprehensive count of global FX turnover that exists, conducted every three years with central banks worldwide. The April 2022 survey put daily global FX turnover at $7.5 trillion, and broke it down by the country where the trade was booked: the United Kingdom at 38.1% of the total, the United States at 19.4%, then Singapore at 9.4%, Hong Kong SAR at 7.1%, and Japan at 4.4%.
Read those five numbers next to each other. London alone books more of the world’s currency trading than the next three centres combined. The relay is not four roughly equal shifts. It is one dominant session, a large second session, and a long tail of much smaller ones — Tokyo among them.
02 Volatility follows the relay, not the clock
This is not a hunch about “quiet Asian sessions” — it is one of the more thoroughly documented findings in market microstructure. Torben Andersen and Tim Bollerslev’s 1997 paper in the Journal of Empirical Finance, “Intraday Periodicity and Volatility Persistence in Financial Markets”, established that FX return volatility follows a strong, repeating intraday pattern tied directly to which centres are actively trading — not a flat baseline with random noise on top, but a deterministic shape that recurs day after day.
The shape is not a single hump. It rises as London opens, rises further and peaks during the London–New York overlap — commonly cited as running roughly 13:00 to 17:00 UTC, the few hours when Europe and the Americas are both fully active — and falls away as both centres wind down. The trough sits in the stretch after New York closes and before London reopens the next day, the exact window that contains the Tokyo session for most major pairs, where Japan’s 4.4% share of global turnover is doing the trading essentially alone.
That is not folklore repeated on trading forums. It is a peer-reviewed, widely cited empirical result, and it has held up because the underlying cause — turnover concentrated overwhelmingly in a handful of financial centres — has not materially changed since 2022 or, in its broad shape, since 1997.
03 What a fixed-window indicator actually does across that relay
Here is where this stops being background reading and becomes a problem with your chart.
An ATR(14), a Bollinger Band width, any volatility measure built on a fixed lookback — computes over the last N bars, full stop. It has no concept of which session produced them. On an hourly chart, ATR(14) spans the last fourteen hours. Depending on when you look at it, that window can straddle the London–New York overlap, the New York afternoon wind-down, and the first quiet hours of the Asian session, all averaged into one number.
At the moment Tokyo opens — roughly 00:00 UTC — an hourly ATR(14) still contains several bars from the London–New York overlap, eight to fourteen hours earlier. The market that generated those bars is closed. The traders who were active in it have gone home. But their volatility is still sitting inside your indicator’s average, quietly inflating a reading that is meant to describe the market you are looking at right now — one where, per the BIS numbers above, only a fraction of global turnover is even awake.
The reverse happens on the way into the London open. An ATR calculated at 07:00 UTC, just before London wakes up, is still full of the Asian session’s comparatively thin ranges — a genuinely quiet market’s number, about to be applied to a market that is seconds away from turning busy.
Either way, the indicator is not wrong about its arithmetic. It is answering a question you did not mean to ask: “how much did price move over the last N bars,” rather than “how much is price actually moving right now, in the session that is open.” Those are different questions, and a fixed lookback window cannot tell them apart.
04 Two nearby currencies, treated as one problem
Take a concrete pair most traders will recognise: USD/JPY, one of the most heavily traded currencies on the planet and the one where the London–Tokyo handoff is least abstract, because Tokyo is Japan’s own session.
At the Tokyo open, USD/JPY is, structurally, waking up into its own domestic session — but the indicator sitting on the chart does not distinguish “domestic session for this currency” from “quiet session generally.” A fixed-window ATR still carries the London–New York overlap’s ranges forward into that first hour, exactly as it would for any other pair. The instrument’s own session relevance to Tokyo does not exempt it from the mechanical blending problem described above; it just makes the mismatch easier to overlook, because it feels intuitive that Tokyo “should” matter more for yen pairs than the arithmetic actually allows for.
This is worth naming because it is the kind of thing a trader who has internalised “London and New York are the big sessions” can still get wrong on a yen pair specifically — assuming the pair’s own home session must be driving the indicator’s current reading, when the number on screen is still, mechanically, mostly a residue of the session that just closed.
05 Why this is not just a forex curiosity
The same mechanism applies to any instrument with a genuine session structure and a volatility indicator with a fixed bar count — it happens to be cleanest to see in FX because the BIS data makes the session imbalance explicit and measurable, rather than a matter of impression. A trader who only checks “is my ATR high or low” without asking which session generated the bars inside it is, in effect, asking a stale question and trusting the answer as current.
06 How to check, without anyone telling you what to use
One. Plot your volatility indicator against UTC session boundaries, not against your local clock. Mark London open (roughly 08:00 UTC), the London–New York overlap (roughly 13:00–17:00 UTC), New York close (roughly 21:00–22:00 UTC) and Tokyo open (roughly 00:00 UTC) on a chart of the pair you actually trade, for a week.
Two. Watch what your indicator’s value is doing right as each session changes hands. Does it drop sharply once the overlap’s bars roll out of the window, or does it stay elevated for hours because your lookback is long relative to the session length? Does it stay artificially low heading into London because the window is still full of Tokyo’s quieter bars?
Three. Work out how many bars of your lookback belong to which session, right now. If you are running ATR(14) on hourly bars at the Tokyo open, count backward: how many of those fourteen bars are actually from the Asian session that just started, versus the London–New York session that just ended? That ratio is the honest answer to “how current is this number.”
Four. Consider whether a session-anchored measure serves you better than a fixed one. This is not a recommendation to change your settings — it is a question worth answering for your own instrument and timeframe before you size a stop off a number that may be several sessions stale.
Five. Do the same check on a second pair before drawing a general conclusion. A single week on a single pair is an anecdote, not a finding. If you see the same session-blending pattern on, say, both EUR/USD and USD/JPY, that is far stronger evidence than either alone — and if you don’t, that is worth knowing too, because the size of the effect will differ by pair depending on how concentrated that pair’s own liquidity is in a particular centre.
Paper trade first. Any observation discussed here is a starting point for your own research, not a signal or a recommendation — test anything you find on a simulated account across multiple sessions before risking capital. Quantzee provides analytical software, not investment advice.
07 The number on your chart is a memory, not a measurement
That is the honest way to describe what a fixed-window volatility indicator gives you: not a live reading of the market in front of you, but a blended memory of however many bars fit inside the window, weighted by nothing in particular. Most of the time the blend is close enough not to matter. At a session handoff — and Tokyo’s open, sitting right after the world’s busiest hours end, is one of the sharpest handoffs there is — the gap between memory and measurement is at its widest.
Quantzee documents the calculation logic behind each of its indicators for exactly this reason — so you can see what window a reading is actually drawn from before you size anything off it. You can read the full guide to global forex indicators, the ATR entry in our glossary, or the published methodology for each indicator.
08 Frequently Asked Questions
Which financial centre dominates FX trading?
Per the BIS 2022 Triennial Central Bank Survey, the United Kingdom accounted for 38.1% of global daily FX turnover ($7.5 trillion total), followed by the United States at 19.4%, Singapore at 9.4%, Hong Kong SAR at 7.1%, and Japan at 4.4%.
Is it really true that FX volatility follows a repeating daily pattern?
Yes — this is one of the most established findings in market microstructure research, formalised by Andersen and Bollerslev’s 1997 study, which found a strong, recurring intraday volatility pattern in FX tied to session activity rather than a flat baseline with random noise.
When is FX volatility typically highest?
During the London–New York overlap, roughly 13:00–17:00 UTC, when both major centres are simultaneously active.
When is FX volatility typically lowest?
In the stretch after New York closes and before London reopens — the window that contains the Tokyo session for most major pairs, where the numerically smallest of the major centres is trading largely alone.
Does a fixed-lookback ATR or Bollinger Band account for this session pattern?
No. It averages over the last N bars regardless of which session produced them, which means its reading can still be dominated by a session that has already closed.
Should I use a shorter lookback to avoid this problem?
A shorter window reduces how many stale bars can sit inside it, but does not remove the underlying issue — it is a question of whether your window is session-aware at all, not just how long it is. That is worth testing on your own instrument rather than assuming a shortcut fixes it.
Does this apply to instruments other than forex?
The mechanism — a fixed-bar-count indicator blending an active session’s ranges into a quiet session’s reading — applies to any instrument with genuine session structure. FX simply has the clearest public data (the BIS survey) showing how uneven that session structure actually is.
Does Quantzee tell me which lookback or session settings to use?
No. Quantzee provides analytical software and indicators intended to support independent research and analysis. It does not provide investment advice, and decisions about settings, instruments and trades remain the trader’s own.
Sources: Bank for International Settlements (2022), Triennial Central Bank Survey of Foreign Exchange and OTC Derivatives Markets · Andersen, Torben G. and Bollerslev, Tim (1997), “Intraday Periodicity and Volatility Persistence in Financial Markets,” Journal of Empirical Finance 4(2–3):115–158.
