Chart pattern · Reversal · Neutral
What is it, in one line
Diverging trendlines, with price making both higher highs and lower lows, widening rather than compressing.
Neutral · Reversal · verdict: Traditional claim, not yet measured here
Diverging trendlines, with price making both higher highs and lower lows, widening rather than compressing.
Method
Conventional target: No standard projection; the pattern signals rising volatility more than a specific target.
Invalidated by: A move that stops widening and reverses back inside the range ends the pattern.
Every other formation on this site publishes an executable rule with its thresholds. This one does not, and the reason is a property of the shape rather than an omission.
The chart formations are detected from swing points, and what separates one from another is a tolerance on how those swings relate. A head and shoulders requires the outer two peaks to match within a tolerance; a triple top requires all three to. That matching tolerance is what stops each rule firing on any three peaks at all.
A broadening formation is defined by the opposite: successive swings that do not match, each one further out than the last. Expressing that needs a rule about the direction a tolerance is violated in, over an unbounded number of swings, and the engine has no such primitive. So nothing is published rather than a rule that would fire on any volatile stretch.
Where this goes wrong
This is the honest version of a gap. The alternative — shipping a loose rule so the page has a number on it — would produce detections that are indistinguishable from ordinary volatility, and a count of those is worse than no count.
An expanding range: higher highs and lower lows in sequence, drawn as two diverging trendlines. It is usually read as indecision and rising volatility rather than as a directional signal, which is why it carries no direction on this page.
Because it has no rule here, it also has no firing rate and will get no measurement from the re-run. The twenty other chart formations all do.
A symmetrical triangle is its mirror image — converging swings rather than diverging ones — and the two are routinely mislabelled on the same chart depending on which swings the drawer picks.
A rectangle is the case where the swings neither converge nor diverge. That one does have a rule here, because "stays within a tolerance" is expressible in a way that "leaves it by more each time" is not.
The absence of a detector does not make the shape unusable — it makes any claim about it unfalsifiable, which is a different problem and worth holding in mind.
What can be said without measurement: an expanding range means each swing is travelling further than the last, so whatever is repricing the instrument is doing so more violently over time. That is a statement about volatility, and volatility is measurable directly. The ATR calculator and the volatility calculator quantify it without needing the shape to be named.
What cannot be said: that the expansion resolves in a particular direction. Nothing here has tested that, and the formation carries no direction on this page for exactly that reason.