Reading the footprint

It is 09:41 ET (21:41 ICT, winter). The NQ 1-minute bar you are watching closes green, three points off its low. You buy the close because green looks strong. Two bars later you are stopped out. What did the bar know that its colour did not show you? Some of it was printed inside the bar, in numbers you did not read. This lesson teaches you to read them, and to be honest about how much they tell you. (The bars in this lesson are synthetic illustrations, not a real date.)

Key terms

A footprint (biểu đồ dấu chân) splits every bar by price. At each price it shows two numbers: contracts that traded at the bid × contracts that traded at the ask Definition.

• At the bid (khớp tại giá mua): a seller crossed the spread and hit a resting buy order. Aggressive selling.
• At the ask (khớp tại giá bán): a buyer crossed the spread and lifted a resting sell order. Aggressive buying.

The candle gives you open, high, low and close. The footprint shows who was aggressive, and where, inside that range. The split comes from the exchange’s aggressor flag on each trade: CME data marks whether the buyer or the seller initiated it. Feeds without that flag have to infer it, which is one reason two platforms can show different footprints for the same bar (M0.07, M3.13).

Term you need: point of control (POC). The bar POC (điểm kiểm soát của nến) is the price inside one bar where the most contracts traded, bid plus ask Definition. M2.01 covers the session POC; this is the same idea for a single bar.

Chart first: one bar, cell by cell

How it works

Reading a cell

Each row is one price; NQ moves in ticks of 0.25 points, so a 1-tick footprint has four rows per point. The cell at 20,401.00 reads 180 × 150: 180 contracts sold into the bid, 150 bought at the ask. Neither side dominated there. At 20,400.25 it reads 85 × 40: sellers did roughly twice the aggressive volume of buyers. The difference ask minus bid is that price’s delta (M3.04 owns it); added over every row it gives the bar delta, +273 in the figure.

Some platforms group rows (for example 4 ticks a row). Always check the row size before you compare numbers between charts.

The bar POC

Add bid and ask in each row and find the largest total. In the figure that is 20,401.25: 210 + 230 = 440 contracts. The POC tells you where this bar did most of its business Definition. Here it sits in the lower middle of the bar, below where the bar closed.

Traders often read a POC at the bar’s extreme as a sign of weakness in that direction. As a signal, that was tested on NQ and not supported (the evidence box below). Read the POC as a location, not a forecast.

The diagonal imbalance

You do not compare bid and ask on the same row. A buyer lifting the ask at 20,402.50 is trading against a seller hitting the bid one tick lower, at 20,402.25, because that is where the two sides of the spread met. So the comparison runs diagonally Definition:

• Buy imbalance at price p: ask at p ÷ bid at p − 1 tick. At 20,402.50: 132 ÷ 31 = 4.3×.
• Sell imbalance at price p: bid at p ÷ ask at p + 1 tick.

A cell counts as an imbalance when the ratio passes a threshold you choose. The threshold is a setting, not a law: the ATAS stock default is 150%, the figure uses 300%, and some desks use 400%. Raise it and fewer cells light up. Platforms often add a minimum volume so that 6 ÷ 1 on tiny numbers does not count.

Initiative and responsive: a description

Module 1 gave you two words for aggression (M1.03). Initiative aggression moves with price into new territory: in the figure, buyers lift every offer as the bar rises to its high. Responsive aggression pushes against an extreme: sellers hitting bids at the top of a rising bar. The footprint shows you where the aggression sat, and your value map from Module 2 tells you whether that place was inside or outside value. Together they let you describe the bar in plain words Definition.

Myth / hypothesis: “Initiative aggression continues and responsive aggression reverses; a bar with heavy selling at its high will roll over.” Lore These rules are widely taught. On NQ they were tested as forecasts of the next hour and not supported: bars with the signal behaved about like bars without it (box below). Treat each one as a hypothesis you could test, not as a rule.

Why it is still worth knowing

You still need to read the footprint. It gives you a shared vocabulary for the auction: who pushed, where, and how hard. It shows you where your read is plainly wrong, and that is where a stop belongs. Footprint signals in the same public study widened both the best and the worst excursion that followed: they flag that a move is getting bigger, not which way it goes PlausibleOne trader's study. And every pattern you meet in this module is a claim you can write down and test against a baseline, the way the box below does.

Worked example: two green bars, two descriptions

Synthetic morning, NQ 1-minute footprint, tick 0.25 points.

Bar A is the bar in the figure: 20,400.00 to 20,403.00, closing on the high. Reading bottom up: sellers were heavier at the low (85 × 40 at 20,400.25), the two sides met around the POC at 20,401.25, then buyers lifted the offer at every price into the high. The top four prices are buy imbalances at 3× (for example 150 ÷ 45 = 3.3× at 20,402.25). Description: initiative buying through the upper half of the bar, delta +273.

Bar B, two minutes later: 20,403.00 to 20,405.00, also green. Its top three prices read:

Delta over those three prices: (60 + 45 + 70) − (280 + 260 + 290) = −655. Description: responsive selling at the top of a bar that still closed green. The candle says “up two points”. The footprint adds that sellers hit bids hard at the high.

What you have learned for certain is the description. What you have not learned is the next bar. Heavy selling into the high of an up-closing bar was tested on NQ as a sign of what comes next, and it did no better than ordinary bars (box above). So the useful move is not “short the close” or “buy the dip”. It is to write down what would confirm or cancel the read:

• If the next bars trade back above 20,405.00 and the ask side takes over again, the sellers at the high were absorbed; the bar-B read is cancelled.
• If the next bars cannot get back above 20,404.50 and selling continues at lower prices, the sellers are now initiating. M4.09 shows how to write that as a confirmation rule you can score.

The mirror works the same way on the short side: a red bar with heavy ask volume at its low is responsive buying, and it carries the same grade as a forecast.

Do it on the platform

Common mistakes

Common mistake: Treating a description as an edge. “Sellers hit the high” is true of bar B. “So it reverses” is a forecast, and on NQ that forecast did no better than bars without the pattern. Read the footprint for what it records, then plan for both outcomes.

Common mistake: Comparing bid and ask on the same row. An imbalance is diagonal: ask at one price against the bid one tick below. Same-row ratios mix two different moments of the spread.

Common mistake: Reading the footprint without location. Heavy aggression in the middle of a balanced day is routine two-sided trade. The same print at the edge of value is worth noting. The footprint is one leg of a read; location (M2) and auction state (M1) are the others.

Recap

• A footprint shows bid × ask volume at every price inside a bar: who was aggressive, and where.
• The bar POC is the price with the most volume; a diagonal imbalance compares the ask at one price with the bid one tick below, at a threshold you choose.
• Initiative and responsive are descriptions of where aggression sat. As forecasts of the next move they are Lore on NQ.
• The candle’s colour hides the inside of the bar; the footprint shows it, and your plan says what would confirm or cancel the read.

Further reading

• Footprint charts: how to read order flow: reading the footprint diagonally, and drilling before trading it.
• Numbers Bars: diagonal bid/ask imbalance, Sierra Chart documentation: how one platform defines the diagonal comparison and its thresholds.
• Stacked Imbalances, ATAS knowledge base: the stock ATAS view of imbalances, used again in M3.03.
• Order Flow, Measured: all claims: the public practitioner study behind the evidence box (rows FP-06, FP-11, FP-12, DA-06, DA-08, DN-07).
• Our lab: initiative and responsive are graded as a definition, and Lore as a signal; footprint signals are read as volatility flags, not direction.

This lesson connects to: M2.01 (the POC, here for one bar) · M3.02 (absorption: when aggression meets a resting order) · M3.03 (imbalances in runs: stacking) · M3.04 (delta, the per-bar sum of these cells).

Next: M3.02 takes the heaviest cells you just learned to read and asks what happens when aggression meets a resting order and price does not move.

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