Initial Balance

It is 10:30 ET (22:30 ICT, winter) on an NQ morning. The first hour has traded between 21,000 and 21,060. For the rest of the session, every move gets measured against that range: does price leave it and stay out, or keep coming back inside? This lesson shows you how to mark and measure it, what the auction vocabulary around it means, and what has actually been measured about it on NQ, which is less than the folklore suggests.

The Initial Balance (cân bằng ban đầu, IB) is the price range of the first hour of the regular session: 09:30–10:30 ET (21:30–22:30 ICT in winter), the A and B periods of a 30-minute TPO chart (M2.06) Definition. It is the day’s first two-sided negotiation. Mark three lines:

• IB high and IB low: the extremes of the first hour.
• IB mid: halfway between them. Price above the mid at 10:30 describes buyers getting the better of the first hour; below it, sellers. That is a description of the hour, not a prediction: whether IB-mid location forecasts the rest of the day is not yet measured in our lab.

The IB is not final until 10:30 ET; an “IB high” at 10:00 is still developing. Some platforms build it from overnight data or a different first period: use the RTH 60-minute version, the same way every day.

Chart first: the IB as the day’s reference frame

Measure the width, not just the lines

An IB of 60 NQ points means one thing on a quiet day and another on a volatile one. So measure width against recent sessions: divide today’s IB range by the median IB range of the last 20 sessions Definition. A ratio near 1 is a typical IB; one in the bottom third of recent days (roughly below 0.8) is narrow; one in the top third is wide. This is the definition our lab uses in its pre-registered IB study.

After 10:30: extension or containment

Everything after the first hour is described by how price treats the IB lines Definition:

• IB extension (mở rộng IB): price trades beyond IB high or IB low. If it then holds beyond, with volume and time building outside the old range, auction traders call that acceptance: initiative activity (M1.03) is moving the auction to new prices. Extensions are measured in multiples of the IB range (“price extended 1.5× IB”), which is objective language for how far the day travelled. Use it as a ruler, not a target: in our lab, the 2× extension was reached slightly less often than random prices at the same distance (M4.05 covers this).
• Containment: price stays inside the IB for the rest of the day. In Market Profile language this is close to a Normal Day (M1.04): the first hour did most of the day’s range-finding and the rest is rotation.
• A probe that fails: price trades beyond an IB line, then comes back inside within a period or two. Auction traders call this a rejection: the market looked for business beyond the line and did not find enough to stay.

The difference between acceptance and rejection is never the break itself; it is what happens after the break. Probes are cheap; acceptance takes volume and time. That language is shared vocabulary and worth knowing. What it is not, yet, is a measured trading rule.

Myth / hypothesis: “A failed IB breakout traps the breakout buyers, and their exits drive price to IB mid and then IB low, so short the return inside.” The story is coherent, but the failed IB breakout itself is not yet measured on NQ. The closest public test, one practitioner’s pre-registered NQ study, checked failed breaks of the prior day’s high or low: they went on to the other side of the range no more often than its baseline (−1.1 pp [−4.1, +1.9], n = 983) Lore. Read that study with three caveats: it is one trader’s work, its intervals are not clustered by session, and on its own it supports a claim at Plausible at most. Treat the failed-breakout trade as a hypothesis you score yourself.

What the data says

The same practitioner study measured the popular IB claims on NQ futures from 2018 to 2026, with a final year held out and opened once. Two results matter here; a third, on narrow IBs, follows the evidence box.

The IB breaks on at least one side on most days PlausibleOne trader's study. That held again in the holdout year. It is a base rate: it tells you to expect trading outside the first-hour range at some point, not on which side and not when. The same study found that the first side to break predicted the close only inconclusively (+2.9 pp [+0.6, +5.2], not significant once corrected for the number of tests) Lore.

A wide IB’s extremes hold for the rest of the day a little more often PlausibleOne trader's study. It is the only IB claim in the study that survived that correction, but the holdout year was too small to confirm it, and it describes a kind of day, not a trade with a stop and a target.

Myth / hypothesis: “A narrow IB means the market is coiled, so expect a trend day or a big breakout.” In the NQ study, narrow IBs gave fewer trend days and large extensions, not more (−11.9 pp [−14.8, −9.0], n = 1,809; holdout −6.0 pp, too small to tell) Lore. Our lab checked the same idea on QQQ and SPY 1-hour bars (721 sessions) and found no difference in either direction (+2.1 pp and +2.0 pp, intervals spanning zero). “Compression precedes expansion” is a heuristic that the NQ data so far does not support.

Why it is still worth knowing

The IB is shared vocabulary that every profile trader, platform and later lesson (M4.05, M5.10) uses. It gives the rest of the day a fixed, objective frame, so “1.5 IBs above the high” means the same to everyone, and it tells you as the day unfolds whether you are in a contained day or an extending one. Its base rates are honest scenario inputs: plan for at least one side to break; on a wide-IB day, give some weight to the extremes holding.

Worked example: measuring one IB and reading the break

The synthetic NQ day from the figure.

Step 1: mark and measure. By 10:30 ET the A and B periods have traded 21,000–21,060: IB low 21,000, IB high 21,060, IB mid 21,030, width 60 points. The median IB of the last 20 sessions was 80 points, so the ratio is 60 ÷ 80 = 0.75: a narrow IB. Note what that does not tell you: by the NQ study, it does not raise the odds of a trend day.

Step 2: the probe. In the C period (10:30–11:00 ET) price breaks 21,060 and reaches 21,080, 20 points or a third of an IB above the high. The C letters up there stand alone: single prints (M2.08).

Step 3: the verdict. In D (11:00–11:30 ET) price trades back to 21,040, inside the IB, and the later periods keep building letters between 21,000 and 21,060. The probe above was rejected; acceptance never happened. The day so far is a contained, rotating day with one failed look above.

Step 4: what would change the read. If price had stayed above 21,060 for an hour with volume building between 21,060 and 21,080, that would have been acceptance: an extension, and 21,060 would turn from the top of the range into the first reference below price. The difference between the two days is not the break. It is what came after.

What you do not get is a forecast. “Rejected above, so it goes to IB low” is the first myth box’s hypothesis: to trade it, write the rule down (entry, stop, target, which days count) and score it in your journal first.

Common mistake: Treating a base rate as an edge. “The IB breaks on most days, so I buy every break of IB high.” The base rate has no side: one side breaking is the normal case, and it says nothing about which side, or whether the break is accepted. Entering on the first print beyond the IB, before the auction answers (holding outside with volume, or a quick return inside), has no measured edge on NQ either.

Recap:

• The IB is the 09:30–10:30 ET range (the A and B periods); IB high, IB low and IB mid are the day’s reference lines, and the IB is not final until 10:30.
• Measure width against recent sessions (IB range ÷ median IB of the last 20 sessions), not in fixed points.
• After 10:30 the day is described by extension (beyond, and accepted) or containment; a probe that returns inside is a rejection, read as a description of the auction, not as a signal.
• One public NQ study (Plausible, one trader’s study): at least one side of the IB breaks on most days, and a wide IB’s extremes hold a little more often. Both are base rates, not trades.
• A narrow IB gave fewer trend days on NQ, not more, and the failed-IB-breakout trade is not yet measured: keep both as hypotheses.

Further reading:

• James F. Dalton, Eric T. Jones and Robert B. Dalton, Mind Over Markets (Wiley): the standard book on the IB and day types; read its trading rules as hypotheses.
• Following the Auction: Market Profile Basic Language: IB and period language in plain English.
• Market Profile Course — The Nature of Markets: a structured course covering the opening and its extensions.
• Order Flow, Measured: one practitioner’s public, pre-registered NQ study; claims OI-03 to OI-07 cover the IB.
• Our lab: IB width and IB extensions tested on 721 sessions of QQQ and SPY. Width is useful as context only, and the 2× extension was reached slightly less often than random prices at the same distance.

Prerequisite: M2.06 Market Profile structure · Next: M2.08 Single prints, which the probe in this lesson’s example left behind · Connects to: M1.03 (initiative and responsive activity), M1.04 (day types), M4.05 (the IB in session prep, extensions as a ruler), M5.10 (the IB breakout)

Educational content only — not financial advice. Futures trading involves substantial risk of loss.