Monday Is the Inside Day: 30 Futures and 110,465 Sessions
Updated September 28, 2026
A two-to-one effect, where nobody looks for it
An inside day is a session whose high and low both fit within the previous day's range. Nothing new happened: the market moved inside what it already knew.
Measured across the thirty contracts we have, it happens in 15.7% of sessions. A bit more than one in seven. That number on its own is not interesting.
What is interesting is how it splits by day of the week: 23.2% of Mondays and 12.8% of Tuesdays. Nearly double.
It is the largest effect we have measured on this site. The streak and previous-range studies give one or two points between categories; here there are ten and a half.
The full week
Monday 23.2%, Tuesday 12.8%, Wednesday 13.9%, Thursday 14.0%, Friday 15.9%. Across 110,465 sessions from thirty contracts.
Monday is not merely the highest: it is the only one that leaves the pack. The other four days fit inside three points, with Friday a touch above the middle of the week.
Before looking for an explanation it is worth saying what that Monday actually is. An inside day is measured against the contract's own previous session, and for almost all of these markets the session before a Monday is Friday. In between sit two calendar days with no trading, or nearly none.
So the comparison is not "Monday versus Tuesday" on equal terms. It is "the session that follows a long break" versus "the session that follows another session". That this shows up so strongly is the finding.
How often the session stays inside yesterday's range
30 contratos, 7 familias
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| Day | Stays inside | Sessions |
|---|---|---|
| Monday | 23.2% | 18,768 |
| Tuesday | 12.8% | 23,076 |
| Wednesday | 13.9% | 23,121 |
| Thursday | 14.0% | 23,049 |
| Friday | 15.9% | 22,451 |
| Every session | 15.7% | 110,465 |
n = 110,465 · 2010-06-07 to 2026-09-16 · exchange data
Inside day = its high and low both fit within the prior day's range. The denominator is every session, not only those following an inside day. It is measured on the contract's own calendar day, so the 'Monday' of a market that does not trade at the weekend carries two days without a session, and that of one that does carries none.
Twenty-four contracts have it, six do not
The effect is strongest in currencies and along the Treasury curve. The Canadian dollar goes from 11.2% across the rest of the week to 28.3% on Mondays, two and a half times. The euro, from 12.2% to 27.5%. The five-year note, from 14.0% to 29.5%. The two-year posts the highest Monday in the table, 35.2%.
In index futures it is real but smaller: the ES goes from 12.1% to 21.6%, the Dow from 12.8% to 21.3%, and the Nasdaq only reaches 1.43 times.
And there are six contracts where it simply does not appear: crude oil (15.0% against 13.9%), corn (15.7 against 14.9), wheat (14.7 against 14.4), soybeans (15.7 against 14.0), bitcoin (19.8 against 19.4) and natural gas, which inverts it (12.5 against 13.4).
Energy, grains and bitcoin. The three groups whose weekly calendar does not look like everyone else's.
The inside day: Monday against the rest of the week
Los 30 contratos medidos
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| Contract | Monday | Tuesday to Friday | All | Sessions |
|---|---|---|---|---|
| ES | 21.6% | 12.1% | 13.7% | 3,978 |
| NQ | 17.5% | 12.2% | 13.0% | 3,991 |
| RTY | 17.7% | 12.1% | 13.0% | 2,261 |
| YM | 21.3% | 12.8% | 14.1% | 3,978 |
| NKD | 21.4% | 15.7% | 16.6% | 3,917 |
| GC | 28.1% | 15.7% | 17.9% | 4,039 |
| SI | 25.4% | 15.8% | 17.5% | 4,053 |
| HG | 19.8% | 15.1% | 15.9% | 4,048 |
| PL | 18.8% | 13.5% | 14.5% | 4,052 |
| PA | 20.2% | 17.5% | 18.0% | 4,087 |
| CL | 15.0% | 13.9% | 14.1% | 3,985 |
| NG | 12.5% | 13.4% | 13.3% | 3,738 |
| ZC | 15.7% | 14.9% | 15.0% | 3,761 |
| ZW | 14.7% | 14.4% | 14.5% | 3,784 |
| ZS | 15.7% | 14.0% | 14.2% | 3,689 |
| 6E | 27.5% | 12.2% | 14.9% | 4,068 |
| 6J | 24.6% | 15.3% | 17.0% | 4,034 |
| 6B | 26.3% | 13.3% | 15.7% | 4,107 |
| 6A | 24.7% | 13.0% | 15.1% | 4,046 |
| 6C | 28.3% | 11.2% | 14.4% | 4,104 |
| 6S | 26.6% | 12.8% | 15.4% | 4,087 |
| 6N | 23.6% | 12.3% | 14.3% | 4,055 |
| 6M | 25.4% | 12.7% | 15.1% | 4,051 |
| ZT | 35.2% | 17.7% | 20.9% | 4,042 |
| ZF | 29.5% | 14.0% | 16.7% | 4,018 |
| ZN | 29.1% | 14.3% | 16.9% | 4,033 |
| ZB | 24.9% | 13.2% | 15.3% | 4,050 |
| SR3 | 35.6% | 23.1% | 25.2% | 1,076 |
| BTC | 19.8% | 19.4% | 19.5% | 2,034 |
| ETH | 22.6% | 16.7% | 17.5% | 1,299 |
n = 110,465 · 2010-06-07 to 2026-09-16 · exchange data
Inside day = its high and low both fit within the prior day's range. The denominator is every session, not only those following an inside day. It is measured on the contract's own calendar day, so the 'Monday' of a market that does not trade at the weekend carries two days without a session, and that of one that does carries none. Ordered by family: index futures, metals, energy, grains, currencies, rates and crypto.
The control group was inside the data
Bitcoin trades seven days a week. For bitcoin the weekend break does not exist: its Monday follows a full Sunday of trading, just as its Thursday follows a Wednesday.
If the Monday effect came from the break, bitcoin should not show it. And it does not: 19.8% on Mondays against 19.4% across the rest of the week, over 2,034 sessions. It is the cleanest comparison in the study and it was there without anyone designing it.
Grains and energy have calendars of their own, with sessions that open on Sunday evening or split the day differently. That those are precisely the ones that also fail to show it points the same way.
Points, does not prove. This is a coincidence between which contracts have a long break and which have an inside Monday, over six cases. It is suggestive and it is not proof, and the place to test it is another study: measure the same effect against the actual length of the break, hour by hour.
What this study does not say
It does not say what price does after the inside day. Not whether it breaks up or down, nor when, nor how far. It only counts how often the session stayed inside.
It does not say Monday is a quiet day. An inside day can have a large range if Friday's was enormous; inside is a comparison, not a measure of volatility.
It does not adjust for holidays. A Tuesday following a Monday holiday behaves like a Monday and is counted here as a Tuesday, which if anything dilutes the effect rather than inflating it.
And it does not prove the cause. The coincidence with the weekend break is strong and six cases support it, but six cases are six cases.
What to do with it when you plan the week
The direct part: if you trade currencies or bonds, one Monday in four will stay inside Friday's range. If your Monday plan expects the market to define something new, one time in four it will not, and that is twice what happens the rest of the week.
The indirect part, and probably the more useful one: any daily statistic that mixes Mondays in with the rest of the week is mixing two different populations. In a study about breakouts, about ranges or about gaps, Monday behaves like a different animal.
And if you trade oil, grains or crypto, this effect is not yours. Which is, in its own way, the most useful result in the table: knowing when a widely quoted pattern does not apply to your market.
Frequently asked questions
- What is an inside day?
- A session whose high and low both fit within the previous day's range. The market made no new extreme in either direction. Here it is measured over every session, not only those following another inside day.
- How often does it happen?
- 15.7% of sessions across the 30 contracts, over 110,465 sessions. But the split by day is very uneven: 23.2% on Mondays and between 12.8% and 15.9% across the rest of the week.
- Why does Monday have twice as many inside days?
- The study does not prove it. What it shows is that the six contracts where the effect does not appear — crude oil, natural gas, corn, wheat, soybeans and bitcoin — are the ones with a different weekly calendar or, in bitcoin's case, none at all. Bitcoin trades seven days and posts 19.8% on Mondays against 19.4% across the rest: no break, no effect.
- Which markets show it most strongly?
- Currencies and the Treasury curve. The Canadian dollar multiplies by 2.5 (28.3% on Mondays against 11.2% the rest), the euro by 2.25 and the five-year note by 2.1. The two-year note has the highest Monday in the table at 35.2%.
- Is it useful for trading Mondays?
- On its own, no: the table does not say which way the market will break afterwards, nor when. Its soundest use is as a warning: any daily statistic that lumps Mondays in with the rest of the week is mixing two populations that behave differently.
These numbers, instrument by instrument
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The indicator is open source and free: it marks each session's Initial Balance and gap, and prints beside them the historical rate at which that bucket fills, with its sample size. Same data as the tables above.
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The tables on this page are our own work, built from exchange data. You may reproduce them, translate them or build on them, including commercially, as long as you credit the source and link back to the original page. If you use them, tell us: we like knowing what they get used for.
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Suggested citation:
Perfiltrade (September 28, 2026). Monday Is the Inside Day: 30 Futures and 110,465 Sessions. https://www.perfiltrade.com/en/learn/monday-is-the-inside-day
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