An order block is the last opposing candle before a strong move, marked on the basis that institutions positioned there. Sometimes they did and heavy volume traded. Sometimes price moved fast because nobody was there at all. Both produce the same candle, and only volume separates them.
This is the single most testable claim in price-structure trading, which makes it worth examining carefully rather than arguing about.
What an order block claims
The definition is precise. Find a strong directional move, go back to the last candle that closed against that direction, and mark it. For a bullish order block that is the last down candle before the rally.
The claim attached is that institutions accumulated there, could not fill their entire order before price ran, and will defend the level if price returns.
That is a claim about participants, and claims about participants can be checked, because participants leave volume behind.
Two candles that look identical
Here is the whole issue in one comparison.
Order block A. Price consolidates, one down candle prints, then a sharp rally. On the footprint that down candle shows heavy volume, buying at the bid absorbing everything sold into it, and delta turning positive before price moved. A large buyer was filling.
Order block B. Price consolidates, one down candle prints, then a sharp rally. On the footprint that candle shows light volume across all prices, no absorption, and the rally began because offers were pulled rather than because anyone bought aggressively.
On a candle chart these are the same setup. Both get marked. Both look textbook.
On the retest they behave completely differently. A has a participant with a real position and a reason to defend it. B has nothing behind it, because nobody built anything there.
Two ES order blocks marked identically on a candle chart, with the footprint for each shown beneath. One with heavy volume and visible absorption, one with thin prints and no absorption. Then show what price did on the retest of each.
The three checks
Before treating a level as valid, three questions, each taking seconds.
Did meaningful volume trade there?
Put a volume profile over it. A level sitting on a bulge had participation. A level sitting in a trough did not. This one check removes most of the failures on its own.
Was there absorption at the origin?
Look at the footprint for the candle itself. Heavy volume on one side while price refused to continue is absorption, and it means someone passive was filling. Light, evenly spread volume means the move happened because the other side left, not because anyone was building.
Detail on reading this in absorption, exhaustion and stacked imbalances.
Did aggression drive the departure?
Stacked imbalances in the direction of the move mean someone was aggressively taking price. Their absence means price drifted into empty space.
A level with all three is worth trading. A level with none is a rectangle.
Why this matters more than it sounds
If you take every order block, you are trading a mixture of A and B without knowing which is which. Your results will be the blended average of a setup that works and one that does not.
That produces the specific frustration I hear most often from traders coming from price-structure methods: the setups work often enough to feel real and fail often enough to be unusable, and no amount of refining the drawing rules fixes it.
It is not fixable by refining the drawing rules, because the information needed is not in the drawing. It is in the volume.
What survives, and what improves
The concept survives. Levels where large participants transacted really do get defended, and identifying them is a genuinely useful skill.
What improves is the hit rate, because you stop taking the empty ones. In my experience the filtered version produces noticeably fewer setups and noticeably better ones, which is the trade most people are reluctant to make and the one that matters.
There is a second improvement that is less obvious. When a volume-confirmed level fails, you learn something, because you know there was a participant there and they were overwhelmed. When an unfiltered level fails you learn nothing, because you never knew whether there was anyone there to begin with.
Where the level came from does not matter
Worth saying plainly. I do not care whether you found a level by marking an order block, drawing a demand zone, or reading a volume profile.
The methods are looking for the same thing: a price where a large participant transacted and may still be positioned. They differ only in how they search.
What matters is the verification step, and that is identical regardless of how the level was found. Real volume at the origin, evidence of absorption, and confirmation from the executed orders when price returns. That is the process described in order flow confirmation models, and it works on a level from any source.
If order blocks are how you find candidates, keep using them. Just check them before you trade them.
Frequently asked questions
What is an ICT order block?
The last candle closing against the direction of a strong move, marked on the basis that institutions positioned there and could not fill their whole order before price ran. For a bullish order block it is the last down candle before a rally.
Do order blocks actually work?
Some do. Levels where a large participant genuinely transacted tend to get defended. The difficulty is that the candle pattern used to identify them appears both when heavy volume traded and when almost nothing did, and those two behave in opposite ways on the retest.
How do I know if an order block has institutions behind it?
Three checks. Does the volume profile show real volume at that price, was there absorption in the footprint at the origin, and did stacked imbalances accompany the move away. A level with all three is worth trading. A level with none is a shape.
Why do some order blocks fail immediately?
Usually because nothing traded there. Price moved away quickly not because someone was buying aggressively but because sellers stepped back, leaving a thin pocket. There is no participant with a position to defend when price returns.
Should I stop using order blocks?
Not if they help you find candidate levels. Add the volume check before trading them. Most traders find the failures concentrate almost entirely in the levels with no volume behind them, and removing those changes results more than any adjustment to how the block is drawn.
Is this the same problem as supply and demand zones?
Yes, structurally identical. Both identify a level from candle shape, and both are subject to the same ambiguity, that a fast move can be caused by aggression or by absence. The same volume check resolves both.