Who this entry is for — Charting's most celebrated pattern, rebuilt from its ingredients: why it forms, why it must form, and what the neckline break really says.
Source: J. M. Hurst, The Profit Magic of Stock Transaction Timing, Prentice-Hall, 1970 — Chapter 3, Where Head and Shoulder Patterns Come From (pp. 52–56, Figs. III-2/III-3/III-4).
Prerequisites
Trend lines and channels — the A + B = C recipe. Here one ingredient is added.
Two components and a line
In plain words — A short wave going about its rounds, a long wave reaching its top and rolling over, a line beneath both. The short wave's crest near the long one's top makes the head; the crests either side, lower, make the shoulders.
Hurst takes two model components with the right proportions — those between the ~18-week and ~18-month periodicities — plus the usual line B. Their sum (the book's Fig. III-3) is already "quite a complex bit of price motion for such a simple beginning"; and laying the chartist's favourite lines on it (Fig. III-4) produces what Hurst calls pay dirt:
Almost everywhere we look, a pattern of traditional significance: an uptrend line and a downtrend line, channels, downside and upside breakouts that "forecast" what the chartist expects — and a textbook head and shoulders, sloping neckline and even the "return move" after the break.
The neckline is a second trend line
In plain words — The neckline is no special line: it is the next trend line, drawn through the two lows after the first one broke — with reduced slope because the long cycle is already falling.
The mechanism, dismantled: the first uptrend line connects the first two cyclic lows. When it is broken to the downside and a third low arrives, the second and third lows form a new trend line with sharply reduced upward slope — the neckline. It is the chartist's "rather crude" way of making straight segments conform to the curving channel we now know exists.
And here the model makes a strong promise: a head and shoulders must be formed as a consequence of the price-motion model whenever price motion is turned by a longer-duration component — so long as the time relationship between the two components is similar to that of Fig. III-2. When it is not, a double top comes out instead: same cause, different costume.
Warning — The reverse holds too: the inverted head and shoulders and the double bottom arise from the identical mechanism with the cycles turning upward. And inside a shoulder (or the head) a smaller head and shoulders may form: the shorter components doing their job — all patterns-within-patterns are significant, each at its own scale.
What the neckline break says
The downside break of the neckline confirms the reversal already called by the break of the first uptrend line, and calls for further downside — with the classic return move toward the neckline before continuing. In cyclic terms: the long cycle is past its top, its magnitude is large (proportionality), and the way down has only begun.
Summary card
| Pattern element | Cyclic translation |
|---|---|
| Left shoulder | Crest of the short component, long cycle still rising |
| Head | Crest of the short one near the long cycle's top |
| Right shoulder | Same crest, long cycle now falling |
| Neckline | Second trend line, reduced slope |
| Break + return move | The long cycle rolls over; confirmation and continuation |
| Neckline slope | Depends only on the phase relationship between the components |
Links
- Double top and bottom — same cause, different phase
- Trend lines and channels · Triangles
- Chart pattern verification — Chapter 3's framework
- Hurst tradition — chapter index