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The Liquidity Windowscalp the hours, not the pattern

Evidence: StrongProfessionalScalping · Session

Every scalping strategy has the same denominator: the spread you pay. That spread is not constant through the day — it is narrowest when the most participants are in the market, and the range available to trade is widest at the same time.

Breedon and Ranaldo documented systematic time-of-day structure in FX returns and order flow across six pairs over a decade. The tradeable consequence is narrow: the ratio of range to spread is not the same at 03:00 as it is at 14:00, and a scalper lives entirely on that ratio.

So this is not a pattern. It is a gate you put in front of every other scalping rule you own — including the two above.

Category
Scalping · Session
Timeframe
M1 and M5 execution
Suitable pairs
EURUSD · GBPUSD · USDJPY — and for each pair, only in its own liquid hours
Session
The London–New York overlap, 13:00–16:00 GMT, is the only window this admits by default
Indicators / tools
A logged spread reading by hour · ATR(14) on M5 by hour · session boxes

Valid setup

SC-03 · THE LIQUIDITY WINDOW — WHERE SCALPING IS ARITHMETICALLY POSSIBLE EURUSD · M5 · the same strategy, run in three different hours of the same day GATE 1.08374 1.08403 1.08431 1.08459 1.08488 1.08516 1.08544 ASIA — widest spread, smallest range LONDON — range arrives, spread still unstable OVERLAP 13:00–16:00 GMT — the only window AFTER — be flat 1 2 3 4 00:00 07:00 London 13:00 overlap 16:00 close ① Asia: spread widest, range smallest — ratio worst ② London open: range arrives, spread still unstable ③ Overlap: spread narrowest and range widest at once ④ After 16:00 the ratio collapses — be flat

Exact rules

Entry

  • Before trading anything, spend two weeks measuring. Log the spread and the M5 ATR for every hour of the day on your own account with your own broker.
  • Compute range-to-spread for each hour: ATR ÷ spread. This is the only number that decides when you are allowed to scalp.
  • Trade only in the hours whose ratio is in the top third of your own measurements. On most retail accounts that is the 13:00–16:00 GMT overlap and nothing else.
  • Inside that window, apply whatever scalping trigger you are testing. This gate replaces none of it.
  • Stand down entirely in the hour before and after a scheduled release — the spread widens long before the number prints.

Stop loss

  • Set by whatever strategy you are running inside the window. This gate does not place stops.
  • But size by the window: in the top-ratio hours the same stop distance costs you less in spread, so the same risk buys more position.
  • Risk 0.25%–0.5% per trade.

Take profit / exit

  • Also set by the strategy inside the window.
  • One rule the gate does impose: flat at the end of the window. The ratio that justified the trade stops being true at the same moment every day.
  • Re-measure the hourly table every quarter. Broker spreads change, and so does which hour is worth trading.

Build The Liquidity Window

Reading this page is free and always will be. Taking it is what costs — the complete MQL5 for the rules above, yours to keep, permanently. Five of them cost $10 and they never expire.

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More from Scalping

Microstructure Reversionthe spread's own footprintOrder Flow Imbalancethe book, not the chartThe Cost Arithmeticwork this out before you trade any scalp

Trading carries risk and most retail accounts lose money. Nothing on this page is financial advice or a recommendation to trade. The chart is an illustration of the rules on constructed candles — it is not a record of a trade and not a backtest.