Correlation between majors breaks down at short horizons

[Amanhasnoname]

Daily charts show EURUSD and GBPUSD moving together much of the time, and many traders assume that holds on a one-minute scale. It often does not.

At short horizons, each pair responds to its own flows and news. A UK data release moves GBPUSD while EURUSD barely twitches. A eurozone speech does the reverse. The correlation drops sharply during those windows and then recovers.

This matters for risk. Opening long EURUSD and long GBPUSD feels like two trades, but if the correlation is high during the holding period, it behaves like one trade at double size. When the correlation breaks, the two can move in opposite directions and complicate exits.

Measuring it directly is easy. Pull one-minute returns over a few weeks, compute rolling correlation, and look at how it varies by hour. Many pairs show strong swings, and the numbers rarely match the daily assumption.

A rolling correlation window of thirty to sixty minutes is enough to see how fast the relationship shifts through the day.

How is short-term correlation handled when running several positions at once?