Compression before the open
Posted: Sat Oct 31, 2026 7:55 pm
Compression before the open
In the minutes before a major session opens, price often compresses. Ranges shrink, ticks slow, and the market seems to hold its breath.
The compression reflects reduced participation. Early movers have finished, and the main players haven't arrived. Orders sit on the sidelines waiting for liquidity.
When the session starts, the range expands, often abruptly. The direction of the first move is uncertain, but the expansion itself is quite reliable.
A scalper can use this by identifying the pre-open range and watching for a break. The first break is frequently a fake, as discussed with the London open, but the second leg tends to carry the day.
Measuring the compression helps. Compute the range of the last 15 minutes before the open as a fraction of the average range for that time of day. A ratio below 0.6 signals a tight squeeze.
The tighter the squeeze, the larger the typical expansion, though the relationship is noisy.
The risk is that the break comes with a spread spike, so fills are worse than they appear on the chart.
Context matters for reading compression. A tight range before the London open is expected and carries little information. A tight range in the middle of a normally active session, with tick rates dropping, is a stronger signal that something is being awaited, such as a scheduled release or a large order being held back.
One way to quantify it is to compare the ratio of current range to the same time-of-day average for each of the last twenty trading days. Ratios below one half are rare enough to be notable, and they cluster before events. Logging which compression episodes preceded expansions and which just faded gives a rough hit rate, which is the number that decides whether the signal deserves a place in the routine.
What does the 15-minute range before the London open look like compared with the average on the pair traded here?
In the minutes before a major session opens, price often compresses. Ranges shrink, ticks slow, and the market seems to hold its breath.
The compression reflects reduced participation. Early movers have finished, and the main players haven't arrived. Orders sit on the sidelines waiting for liquidity.
When the session starts, the range expands, often abruptly. The direction of the first move is uncertain, but the expansion itself is quite reliable.
A scalper can use this by identifying the pre-open range and watching for a break. The first break is frequently a fake, as discussed with the London open, but the second leg tends to carry the day.
Measuring the compression helps. Compute the range of the last 15 minutes before the open as a fraction of the average range for that time of day. A ratio below 0.6 signals a tight squeeze.
The tighter the squeeze, the larger the typical expansion, though the relationship is noisy.
The risk is that the break comes with a spread spike, so fills are worse than they appear on the chart.
Context matters for reading compression. A tight range before the London open is expected and carries little information. A tight range in the middle of a normally active session, with tick rates dropping, is a stronger signal that something is being awaited, such as a scheduled release or a large order being held back.
One way to quantify it is to compare the ratio of current range to the same time-of-day average for each of the last twenty trading days. Ratios below one half are rare enough to be notable, and they cluster before events. Logging which compression episodes preceded expansions and which just faded gives a rough hit rate, which is the number that decides whether the signal deserves a place in the routine.
What does the 15-minute range before the London open look like compared with the average on the pair traded here?