24小时市场并不均匀

Every broker repeats the same fact: foreign exchange trades twenty-four hours a day, five days a week. It is true, and it hides more than it reveals. Depth, spreads and the market's capacity to absorb an order without moving price all follow the working day of a handful of cities. A EUR/USD ticket at 14:00 UTC and the same ticket at 21:30 UTC are filled in what might as well be two different markets: one deep and busy, one thin and half-staffed.

This article maps that structure: where the trading day actually lives, when it is deepest, when it is thinnest, and what the weekly close does in between. None of it is timing advice. These are structural tendencies, documented in central-bank data. The questions they raise are ones any cost-conscious reader can put to their own platform.

Four sessions, one continuous day

FX has no central exchange, so it has no opening bell. The "sessions" are conventions: they mark when banks and dealing desks in each financial centre are staffed, quoting prices and warehousing risk. The week begins early on Monday morning in the Asia-Pacific (Wellington and Sydney first, then Tokyo), passes westward to London, hands across the Atlantic to New York, and ends there on Friday afternoon ¹. Because the centres overlap, the day never formally closes between those two points. It thins and thickens as the sun moves.

Treat the minutes as approximate; the shape is what matters. Asia trades while Europe sleeps; London's afternoon is New York's morning; and between New York's close and Sydney's open sits a stretch where almost nobody's working day has begun. Each of those facts prices in a particular way, and the rest of this article takes them in turn.

Where the depth actually sits

Start with geography, because it explains everything else. The BIS Triennial Central Bank Survey, the once-every-three-years census of the FX market, measured global turnover at $9.6 trillion per day in April 2025, up 28% from 2022 ². That turnover is not evenly spread around the planet. Sales desks in four jurisdictions (the United Kingdom, the United States, Singapore and Hong Kong SAR) intermediated three-quarters of it, with the UK alone at roughly 38% and the US at roughly 19% ².

Global FX turnover, April 2025

$9.6tn per day^†

UK share of turnover

≈38%^†

Top four centres combined

75%^†

A market this concentrated cannot be equally deep at every hour. When London is staffed, the desks that handle nearly two-fifths of global flow are quoting; add New York and desks handling well over half of global turnover are awake at once. When neither is, quotes come from fewer desks running smaller books. The market still exists, but there is simply less of it. "Open" and "deep" are different claims.

The overlap: the deepest hours of the day

London's afternoon is New York's morning: roughly 12:00–16:00 UTC in northern summer, an hour later in winter. For those hours the two largest centres are staffed simultaneously, and BIS researchers note that trading activity often peaks in exactly this window ¹. It is also where much of the day's scheduled information lands: major US economic releases fall in the New York morning, and the widely used 4pm London benchmark fix falls late in the window.

For a spread-sensitive reader, depth has two practical faces. Quoted spreads tend to be at their tightest and most stable when the most desks are competing to quote; and a given order moves price least when the book behind the quote is thickest. But deep does not mean quiet — the overlap concentrates news as well as liquidity. It is the market's busiest room, not its calmest.

The thin patch around the daily rollover

The mirror image arrives a few hours later. By convention the FX value date rolls at 5pm New York time (22:00 UTC when New York is on standard time, 21:00 in summer). New York desks are winding down, Sydney is barely open, Tokyo has not started. BIS researchers describe trading between the New York close and the Asian morning as relatively thin. The stretch is known in the market as the "witching hour", the time of day when volume and liquidity are typically at their lowest ¹. It is also the moment overnight financing is applied. Overnight swaps explained covers that cost; this one is about the liquidity.

Thinness has a routine face and a dramatic one. Routinely: fewer desks are quoting, so spreads widen around the rollover hour as a matter of course — many platforms' spread tables say so explicitly. Dramatically: when something does hit a thin market, there is little resting interest to absorb it. The two best-known FX flash events (sterling on 7 October 2016, which fell almost 9% against the dollar before recovering much of the fall within minutes, and the yen on 3 January 2019) both struck in the late New York afternoon and early Asian morning ¹. And a BIS Markets Committee case study of a EUR/USD spike shortly after 23:39 UTC on 29 December 2016, almost 2% in seconds, on no news, measured the Asian session's average best bid-offer spread at more than twice its usual level ³.

Between Monday and Friday the market is never closed. At predictable hours, it is simply much smaller.

Friday close, Sunday open, and the gap between

Once a week the thin patch becomes an actual halt. Most retail FX and CFD platforms stop quoting around the Friday 5pm New York close and resume near the same hour on Sunday, when Asia-Pacific desks begin the new week. The world does not pause with them: news breaks, elections resolve, policy shifts. Monday's first quote can therefore sit some distance from Friday's last: a gap, in the literal sense.

Gaps change what protective orders can do. A stop-loss is an instruction to close at the next available price, not a guarantee of the stop price; across a weekend gap, the next available price can be beyond the stop, and a leveraged CFD position realises the whole distance. That is not a reason never to hold over a weekend. It is a reason to size positions so that the gap case is survivable, which is the territory of position sizing.

Questions worth asking

None of this tells you when to trade, and it is not meant to. It tells you what to ask, of your platform, your instrument and your own habits. For a reader who cares about costs, five questions do most of the work:

• At the hours I usually trade, which centres are staffed? Am I trading in the overlap, in a single-session stretch, or in the rollover patch?
• What does my platform's spread history for my usual pair show at 21:00–23:00 UTC compared with 12:00–16:00 UTC?
• If I hold through the rollover, have I counted the wider spread and the overnight swap as part of the trade's cost?
• If I hold through a weekend, does my position size survive an open well away from Friday's close?
• If my stop is triggered in a thin hour, what execution does my broker's documentation actually promise?

Our own markets pages show session status for each asset class precisely because the hour changes what a quote means; the pricing alongside is reference data on a 60-minute cache (a research view, deliberately not an execution feed), as How North Stone prices its reference data explains. The binding spread at 22:05 UTC is the one on your platform at 22:05 UTC. Knowing that the 24-hour market has a shape is what makes that number worth checking at all.