The New York Session and the 4 PM London Fix

New York brings US data, the deepest liquidity of the day during its overlap with London, and one recurring quirk every trader should know: the 4 PM London fix.

Two halves of the session

The New York session has two distinct personalities. The first half overlaps with London's afternoon and is the most liquid, most volatile window in all of forex. US economic data — employment, inflation, growth — typically lands in the US morning, and with both financial capitals open, the market has the depth to move decisively.

The second half is different. Once London closes, liquidity thins. Afternoon New York trading can drift, chop, or extend a morning trend on lighter volume — a regime where false breaks become more common and disciplined traders often reduce activity.

The London–New York overlap

If the London open is the most important hour, the London–New York overlap is the most important window. For a few hours — broadly the New York morning — both centres are active at once, spreads are tightest, and the day's largest directional moves frequently occur. Pairs with both a US and a European or UK leg (EUR/USD, GBP/USD) are at their most tradeable here.

This is exactly the window our session map and Market Readiness Score (MRS) highlight: volatility, liquidity and the bulk of scheduled US data converge, so conditions for entering a trade are usually at their best.

The 4 PM London fix

There is one recurring event inside this window worth understanding: the 4 PM London fix (the WM/Reuters benchmark). A large amount of institutional flow — from funds rebalancing to corporates hedging — is executed at or around this benchmark rate. The result can be a burst of order flow that pushes a currency in one direction into the fix and sometimes unwinds shortly after.

You do not need to trade the fix, but you should respect it: a sharp, "newsless" move around 4 PM London time is often just the fix doing its work, not a new trend.

How to trade the session

• Front-load your focus. The New York morning, overlapping London, is where the edge lives. Treat the afternoon with more caution.
• Don't confuse the fix with a signal. A spike into 4 PM London that reverses afterward is mechanical flow, not direction.
• Let US data set the regime. When a major release prints, the overlap can produce the day's defining move — size for it.

The bottom line

The New York session offers the deepest liquidity of the day while London is still open, then quietens once it closes. Know where you are in that arc — and know that the 4 PM fix can move price for reasons that have nothing to do with the chart.