In 1963 Benoît Mandelbrot noticed something about cotton prices that every trader already felt: large changes tend to be followed by large changes, of either sign, and small changes by small ones. Calm comes in stretches, and so do storms. Volatility has a memory even when direction does not.
That memory gives markets a rhythm. A range narrows day by day as buyers and sellers drift towards agreement, positions pile up on both sides of a level, and the news everyone is waiting for has not yet arrived. Then something resolves, and the stored-up disagreement is released at once. The quiet was not the absence of risk. It was risk being wound up.
On the chart — the shapes of compression
Most of the classic continuation patterns are drawings of a narrowing range. The symmetric triangle squeezes from both sides; the ascending and descending triangles hold one side flat while the other closes in. Bull flags, bear flags and pennants are short pauses after a sharp move; rising and falling wedges narrow while they drift; the rectangle and the channel keep the range steady. The broadening formation is the same idea run backwards: a range that keeps widening is uncertainty growing, not settling.
Around the price — measuring the squeeze
Envelopes turn the eye’s judgement into a number. Keltner channels scale with the average true range, Donchian channels with the highest high and lowest low, VWAP bands with dispersion around the volume-weighted price, and Bollinger Bands with the standard deviation. When the bands pinch together, traders call it a squeeze: the market is unusually quiet compared with its own recent past.
In the model — calm that does not last
Volatility models such as GARCH write the rhythm down. Today’s variance is built from yesterday’s variance and yesterday’s shock, so calm predicts calm — but only for a while, because the model also pulls volatility back towards its long-run level. An unusually quiet market is, in this view, a market that is likely to get louder.
The same shape turns up far from markets. In 1910 the geologist Harry Fielding Reid explained earthquakes as elastic rebound: the ground on either side of a fault creeps past slowly for years while the fault stays locked, strain builds silently, and then it is released in one slip. Stillness on the surface was storage underneath. And like Mandelbrot’s prices, the pattern looks the same whether you watch minutes or months, which makes it a cousin of the fractal and of the threshold.
What compression does not tell you is which way the spring will jump. A tight triangle says a large move is more likely than usual; it says much less about its sign, and plenty of squeezes simply fizzle out into another quiet range.
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