Pennant: A Shape That Breaks Both Ways
A pennant is a sharp move followed by a brief triangle whose boundaries converge, traded on a break in the direction of the original move. Converging shapes resolve in both directions, and the ones that resolve the other way are given a different name, which flatters the pattern's record.
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How it works
A sharp directional move, then a brief pause in which the highs come down and the lows come up. The two boundaries converge toward a point, and the pattern is traded on a break in the direction of the original move.
The distinction from a flag is the boundaries. A flag’s are roughly parallel, so its break price barely moves. A pennant’s converge, so the break price falls every bar on the upper side and rises every bar on the lower one.
Brevity is part of the definition. A pennant is a short pause — conventionally one to three weeks on a daily chart. A converging triangle that takes three months is a symmetrical triangle, a different pattern with no directional claim attached.
The naming problem
A converging triangle is a shape that must resolve, and it can resolve either way. When it resolves in the direction of the prior move, it is a pennant and the pattern worked. When it resolves the other way, it is usually described as a reversal — and it stops being counted as a pennant at all.
That is a selection effect built into the vocabulary, and it is worth naming plainly. If the failures are renamed rather than recorded, the pattern’s apparent reliability is a property of the naming convention rather than of markets.
The fix is to count both. Every converging triangle after a sharp move, recorded before the resolution, with the direction it eventually broke. That is a few hours of work on a chart and it is the only version of the question that can be answered.
The apex is a deadline. As the boundaries converge, the space price can occupy shrinks toward nothing, so a break becomes arithmetically inevitable. That is not a prediction about the market — it is a consequence of drawing two converging lines, and it would be true of any shape drawn that way.
In practice: what the break is worth
Every breakout claim needs a base rate beside it. On the S&P 500 from 1950 to 2026, 59% of all ten-day windows ended higher, so a pennant break followed by a higher close ten sessions later has only matched what the index did from a randomly chosen day.
A pennant method has to clear that bar, not zero. If its breaks close higher ten sessions later less often than a random day does, the shape is subtracting value rather than adding it.
The base rate is the null model: what holding looks like with no pattern involved. A pennant method has to beat it on a real instrument before the shape is contributing anything the underlying breakout was not already doing.
Volume contracting through the pennant and expanding on the break is the classical confirmation, and it is the only element not derived from price. A break on shrinking participation is the pattern’s own warning sign.
The stop is the opposite boundary, and that boundary is moving. Late in the formation the two sides are close together, so the stop is tight — which sounds good and means the position is being placed where a small counter-move removes it. Early in the formation the stop is wide. The same pattern therefore offers a completely different trade depending on when you take it.
Aggregate the chart and the triangle disappears. Ten daily bars become two weekly bars, and two bars cannot converge. The formation is a property of the resolution.
A gap out of a tightening apex is common — the pattern compresses into a catalyst — and it removes the entry. The cleanest resolutions are frequently the ones nobody could take.
Each attempt pays a round trip. Four marginal breaks at $0.06 a share each cost $0.24 a share before the real move arrives, and a converging shape near its apex produces several in quick succession.
And both boundaries are yours. Which highs and which lows define them is a choice, and a slightly different choice puts the break at a different price on a different bar.
What a pennant is not
It is not a small symmetrical triangle with a guarantee attached. It is a small symmetrical triangle with a directional expectation attached, and the expectation comes from the move before it rather than from the shape.
It is not a flag. Converging versus parallel changes where the entry is and how the stop behaves over time.
It is not defined numerically. How sharp the prior move, how many bars the triangle, how much convergence — none of it is specified.
And it is not evidence of compression in the market. It is evidence that the highs you selected are falling and the lows you selected are rising, which is a statement about your line choices.
How this connects
A small symmetrical triangle after a sharp move - which makes it a flag with converging boundaries rather than parallel ones.
The pole matters as much as the shape. Without a sharp prior move there is nothing being interrupted, and the pattern is just a small range.
It is a compression pattern, so the honest information is that movement is narrowing and cannot narrow forever.
The breakout is the trade, carrying the usual risk that a small move clearing a narrow boundary looks more decisive than it is.
And the boundary supplies the invalidation, which is the pattern’s real practical value - a defined level where the idea is wrong.
When it fails
The main failure is the break in the wrong direction, which is not recorded as a pennant failure because the shape gets renamed. Any honest evaluation has to log the formation before it resolves.
The second failure is the apex overrun. Price reaches the point where the lines meet and simply continues sideways, at which point there are no boundaries left and no pattern.
A third is the late entry. Taking the break in the last few bars before the apex gives the tightest stop and the highest chance of being removed by ordinary noise, because the shape has compressed to less than the instrument’s usual bar range.
A fourth is repeated marginal breaks. A converging shape produces several small violations of each boundary as it tightens. Trading each one is several round trips for one eventual move.
And a fifth is the missing volume check. Contracting participation into the apex is what the classical version requires; without it the triangle is simply a quiet stretch of chart with two lines on it.
The original data
The benchmark any pennant count has to beat comes from the S&P 500: 59% of its 19,290 ten-day windows between 1950 and 2026 finished higher, and 53.1% of single days closed up. A continuation pattern that works less often than that over the same horizon is adding nothing a buy-and-wait position did not already provide.
The measurement this pattern specifically needs is a direction count, and it is one you have to make yourself. Log every converging triangle that follows a sharp move — before it resolves — and record which way it broke. If continuation and reversal come out near even, the pennant is a coin flip with a name on one side, and every published claim about it is a report on the half that kept the name. That count takes an afternoon on a year of charts, and no article can do it for you because the recording has to happen before the outcome is known.
Related
Symmetrical triangle is the same shape without the directional claim. Bull flag is the parallel-boundary version, with the breakout arithmetic in full. And breakout is what the entry is once the drawing is set aside.
I am suspicious of pattern names here. A converging triangle after a big move breaks upward and it is a pennant that worked; it breaks downward and suddenly it was a reversal pattern all along. Same shape, two names, and only one of them gets counted, so count both.
— Michael Whitman
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