London-New York Session Overlap, Explained
“The London-New York overlap is the best time to trade forex” is close to universal advice in retail trading content. What’s less universal is the number behind it. Depending on which page you land on, the overlap carries 37% of daily volume, or 50%, or “over 70%.” Those can’t all be right, and the spread between them is worth understanding before you treat any of them as fact.
Table of contents
- What the overlap actually is
- The number that’s actually sourced
- Where the inflated numbers come from
- What actually drives it
- Where this gets tedious by hand
What the overlap actually is
The London session and the New York session each run roughly eight hours, and for about four of those hours, both are open simultaneously — broadly the late-morning-into-afternoon window in London time, early-morning-into-midday in New York time (exact clock times shift slightly with each region’s own daylight-saving schedule, since the UK and US don’t always change clocks on the same date). For that stretch, participants from both of the world’s two largest financial centers are active in the market at the same time.
Four sessions structure the full 24-hour forex day: Sydney opens the week, Tokyo follows, then London, then New York, each overlapping briefly with its neighbors before the next one takes over. The London-New York window gets the most attention specifically because it’s the overlap between the two largest individual sessions by turnover, not because overlaps in general are automatically significant — the Sydney-Tokyo overlap exists too, and covers a real but much smaller share of global activity, mattering more for AUD, NZD and JPY pairs specifically than for the market broadly.
The number that’s actually sourced
The most credible figures here trace to two places worth naming directly. The Bank for International Settlements runs a Triennial Central Bank Survey of global foreign exchange turnover — the standard, authoritative reference for questions like “how much of global FX volume happens where.” Its most recent published breakdown puts London at roughly 38% of global daily FX turnover and New York at roughly 19%, individually — the two largest single-location shares by a wide margin.
Separately, OANDA’s own data team published an analysis specifically on session timing, built on more than 70,000 data points across six major currency pairs over a full year (2024), with the methodology disclosed: average half-hourly trade volume as a percentage of the daily total. Their finding: the London-New York overlap accounts for roughly 19% of the trading day’s length, but around 37% of average daily volume — a real, name-attributable, methodology-disclosed figure, not a repeated blog assertion.
[Screenshot: SS-OVERLAP-01 — 24-hour activity distribution with the overlap highlighted]
Where the inflated numbers come from
Search further and you’ll find the same underlying idea — the overlap concentrates a disproportionate share of volume — reported as 50%, “55%+,” or “over 70%,” usually with no disclosed sample, no named source, and no methodology. That’s a familiar pattern in this niche: a real, modest, well-sourced number (37–38%) gets paraphrased across enough blog posts that it drifts upward, and by the time it reaches “over 70%,” it’s no longer traceable to anything.
We’re not calling every one of those higher figures deliberately fabricated — some may simply be loose, uncredited restatements of the real number that grew with each retelling. But the practical instruction is the same either way: the number worth citing is the one with a named source and disclosed methodology behind it (BIS’s survey, OANDA’s own dataset), not whichever version sounds most dramatic.
What actually drives it
The mechanism behind the concentration isn’t mysterious. More participants trading the same instruments at the same time produces more genuine two-way interest, which tends to mean tighter spreads and a higher volume of executable size. On top of that, major US economic releases — nonfarm payrolls, CPI, FOMC decisions — are scheduled to land at 8:30am ET, which sits directly inside the overlap window. That’s not coincidence dressed up as pattern; it’s a real scheduling fact that adds a structural reason for concentrated volatility on top of the participation overlap itself.
[Screenshot: SS-OVERLAP-02 — quiet session vs. overlap window price behavior contrast]
This is also the generic, cross-asset version of a more specific idea taught in session-based price action frameworks: that different parts of the trading day tend to serve different roles — one part building a range, a later part testing or sweeping it, a later part still where the more directional move tends to show up. That specific model deserves its own explanation rather than a rushed summary here, but it’s worth flagging as the more granular cousin of the general “overlap = more activity” point covered above.
What this means for different approaches
Concentrated activity isn’t uniformly good news depending on what you’re actually trying to do. For a trader looking for size and fill quality on directional moves, the overlap window’s depth and tighter spreads are a genuine practical advantage — there’s more real interest on both sides of the market to trade against. For a trader running range or mean-reversion approaches, the same window can be actively unhelpful: more participation and wider real ranges tend to work against strategies that depend on price staying contained. Neither of these is a value judgment on the overlap itself. It’s a reminder that “more volume” isn’t automatically “better conditions” — it depends on what your approach actually needs from the market.
Where this gets tedious by hand
Knowing the overlap exists is easy. Tracking exactly where session boundaries fall for the instrument you’re watching — accounting for each region’s own DST calendar, which don’t move on the same date — and doing that consistently every day, is a small but real source of friction that adds up.
One way to handle that: a tool that maps session windows and their boundaries directly onto the chart, adjusted automatically rather than tracked by hand. SSM IQ Price Action with Sessions and PO3 does this — session context kept current without recalculating clock times yourself every time the clocks change somewhere. That’s not a claim that trading inside a busier window guarantees a better outcome; wider participation cuts both ways, and volatility means larger moves against a position just as much as in its favor. It’s a tool for seeing the session structure this article describes, without doing the time-zone math manually.
Whatever you use to track it, the underlying fact stands on real sourcing: the overlap does carry a disproportionate share of activity — by the most credible numbers available, roughly 37%, not 70%.
Related SSM IQ Tools: SSM IQ Price Action with Sessions and PO3 Related Articles: Power of Three: Accumulation, Manipulation, Distribution Sources: Bank for International Settlements, Triennial Central Bank Survey (global FX turnover by location). · OANDA data team, session volume analysis (70,000+ data points, six currency pairs, 2024).
SSM IQ tools are analytical software, not investment advice. Trading involves substantial risk. Author: SSM IQ Research · We Are Tech Sp. z o.o. · Updated: 2026-08-16