Research · a claim, tested

Does the opening range set the day?

Opening range breakout is the third report this category sells by name, and it fails for a reason that has nothing to do with statistics: on 99.8–100.0% of sessions the range is broken. A signal that fires every single day has not selected anything.

100.0%of sessions break the opening range

51.4%of breaks closed beyond the edge

51.0%for a matched arbitrary level — the control

7,811breaks measured on 5-minute bars

The claim

Mark the high and low of the first 30 minutes after the open. Trade the break. The story is that the opening auction sets the day's boundaries, so leaving them is information.

What we measured

This one needs a finer timeframe than the rest of our work: an opening range belongs to a specific half hour, so it cannot be answered from hourly bars. We used the 5-minute archive on the four major pairs, taking the first 30 minutes after the London open and following the session for 8 hours.

The open is resolved through each day's own clock. London and New York keep their own daylight-saving calendars, so pinning the open to a fixed UTC hour tests the wrong half hour for several months of every year. We resolve the city's local time per day instead.

As with every claim on this site, the break is scored against a matched level — a line at a comparable distance from the same midpoint, drawn from that market's own pool of break distances.

The result: two separate failures

First, it selects nothing. The range is broken on essentially every session in every market we tested. A filter that admits 100% of days is not a filter; it is a restatement of the fact that markets move.

Second, the break itself carries almost nothing. Once broken, the session closed beyond that edge 51.4% of the time, against 51.0% for the matched level — 0.4 points.

Market	Sessions	Range broken	Median range (% of price)	Closed beyond	Matched level	Δ
EUR/USD	2,001	100.0%	0.121%	51.4%	51.0%	+0.4
GBP/USD	1,899	99.9%	0.139%	53.3%	53.9%	-0.6
USD/CHF	1,452	100.0%	0.127%	50.6%	50.1%	+0.5
USD/JPY	2,465	99.8%	0.111%	50.8%	50.5%	+0.3

The cost problem underneath both

The median opening range is around 0.12% of price. Entering on the break means entering after the market has already travelled that far — you pay the spread for a move that has happened, in exchange for 0.4 points of edge over an arbitrary line.

What we would actually say

Check how often your signal fires before you check whether it works. This one fires every day, and that alone settles it.
The opening hours are genuinely the biggest of the day for size — the London and New York opens run over twice a typical hour. That is a real fact about volatility, and it is not a fact about direction.
Cutting the clock finer does not rescue an edge. We tested the same grid at 5 and 30 minutes: the buckets shrink and the spread does not.

Full method in section 7 of the evidence page, and the size-versus-direction split in section 13.

Other reports this category sells, tested

Do weekend gaps fill?"Gaps fill 90% of the time" is true and empty — a matched midweek move fills just as often. The indices do the opposite.Does yesterday's high or low matter?68,688 breaks across 19 markets. The level holds 50.4% of the time — slightly less than an arbitrary level the same distance away.When does the day's high and low actually form?"The high forms at the open" is the boundary you chose, not the market. Move it and every single market changes its answer.Does the first hour set the day?A green first hour tells you the first hour was green. Not one of 17 markets reaches even a weak significance bar.Does the trading day of the month matter?The chart this whole category is built on. 285 slots tested, 0 clear the bar, and the strongest anywhere reaches z = 2.99.The best time to trade forexThe overlap is real — as a movement and cost argument, not a direction one. The half that survives a holdout is WHEN, not which way.Does Bitcoin move on the weekend?The weekend is an ordinary trading period whose timetable is a different timetable — the biggest hour moves from 14:00 to 00:00 UTC.

Every claim we have tested, including the ones that held, is on the reports index.

We publish the tests that failed as loudly as the ones that held. Every number on this site carries its sample size, and every claim carries what it was measured against.

Read the whole evidence page →