What is actually narrowing
Take the high minus the low of each candle. In a compression, that number shrinks — not once, but steadily, over a run of candles. The chart visibly tightens into a wedge.
What that measures is disagreement. A wide candle means buyers and sellers were far apart about what the thing was worth, and both were willing to trade a long way from the middle. A narrow candle means they have converged: everyone roughly agrees on a price, so nobody needs to move far to transact.
Why it resolves
Agreement is unstable. A market at which everyone agrees on the price is a market where almost nobody has a reason to trade, and volume drains away with the range. Then one piece of information arrives — anything — and there is very little resting on either side to absorb the reaction.
That is the mechanism, and it is worth understanding rather than memorising: the move after a compression is often large because the book was thin, not because the wedge shape has magical properties.
The direction trap
Here is where most people lose money with a correct observation. The wedge tells you a move is coming. It does not lean either way.
Human beings are extremely good at seeing a direction in a wedge that is not there — a slight upward tilt, a couple of closes near the top, and the mind constructs a bullish story. The tilt of a compression has very little predictive content, and acting on it means taking a directional bet while telling yourself you are reading structure.
A compression is a statement about volatility, not about direction. Treat it as the second and it will be right half the time, which is exactly what a coin does.
The disciplined use is to note that a move is loading, to mark the two edges of the range, and to wait for the resolution to tell you the direction rather than guessing it in advance.
Measuring it without an indicator
You do not need Bollinger Bands or an ATR reading to see this. Do it by eye, then confirm with arithmetic:
- Take the high-minus-low of the widest candle in the recent stretch.
- Take the same for the most recent candle.
- If the second is under a third of the first, and the shrinking has been steady rather than a one-off quiet day, you are looking at a compression.
On the first chart above, six rupees became forty-five paise — a factor of thirteen. That is unambiguous. A factor of 1.5 is just a slow afternoon.
Entering inside the compression, positioned for the direction you expect. It is the worst place on the chart to be: the range is tight so nothing moves in your favour, the resolution can go either way, and if it goes against you the move is violent precisely because the book was thin. Waiting costs you the first part of the move and saves you from half the outcomes.
Read it yourself
Measure before you reveal.
- Roughly how many times wider is the first candle's range than the tightest one?
- What is the volume doing while the range narrows?
- Before the resolution appeared, was there anything on this chart that told you which way it would go?
Show answers
1. About sixteen times — roughly 4.1 against 0.25. An unmistakable compression.
2. Falling steadily, from 72 down to 10, bottoming with the range. Both series drain together, which is the confirmation that this is genuine compression and not a coincidence of quiet candles.
3. No. That is the entire point of the exercise. It resolved upward, and it could equally have gone the other way with the same preceding chart. If you found a reason, you constructed it after the fact — which is the habit this lesson exists to break.
Terms used
- Range
- High minus low, for a single candle or a stretch of them.
- Compression
- Successive ranges narrowing steadily over a run of candles.
- Expansion
- The opposite, and usually how a compression ends.
- Resolution
- The move that ends a compression, in whichever direction it comes.
- Thin book
- Few resting orders on either side — why post-compression moves travel so fast.