A quién sirve esta entrada — Post-book Hurst's most famous tool: take the price, displace it forward by half a wavelength, and you get a line that is already drawn for the next half cycle. When price crosses it, you have a signal — and a ruler for the target.
Fuente: JM Hurst's Cycles Course (Cyclitec, ≈1973) and the Hickson / Sentient Trader tradition. The FLD does not appear in The Profit Magic of Stock Transaction Timing (1970) — in the book, the objective-signal role belongs to the valid trend line.
Prerrequisitos
Phasing analysis (where the right period comes from) and, from the book, the half-span averages — its closest mathematical relative.
Definition and construction
The FLD of a cycle of period P is a representation of price — typically the median price (H+L)/2 — displaced forward in time by ½·P bars. Three immediate consequences:
- the line is already known for the next ½·P bars: it is past price, displaced — no computation can redraw it (the only line legitimately projectable into the future);
- when price crosses its own FLD, the event is an action signal: upward a buy candidate, downward a sell candidate — always within the phasing context;
- the crossing carries a ruler: the move from the trough to the crossing tends to be half the total move → target = crossing + (crossing − trough).
The mathematical intuition — On a pure cycle, displacing by half a period is the same as inverting the wave (sin(x−π) = −sin x): the FLD is the cycle upside-down, the crossing falls on the zeros — exactly halfway between trough and peak — and the target lands on the peak. On real prices (sum of cycles plus trend) the rule becomes approximate: a ruler, not a promise.
FLD and VTL: the two signals compared
| VTL (book, 1970) | FLD (course, ≈1973) | |
|---|---|---|
| Construction | Line through two valid troughs (or peaks) | Price displaced by ½ period |
| Signal | Break of the line | Price/line crossing |
| Lead | After the second pivot confirms | The line is known half a cycle in advance |
| Ruler | Via half-span (Ch. 6) | Included: target = 2·crossing − trough |
In the post-course tradition they coexist: the VTL for pivot discipline, the FLD for timing and targets.
Limits and context
- The period comes from phasing, not from a fixed nominal: the target cycle's current wavelength — a wrong period shifts the line and breaks the ruler.
- Never alone: the tradition binds it to an underlying trend and higher-cycle phasing consistent with the direction.
- To confirm long-cycle troughs without waiting for their crossing: the synchronicity trick.
Summary card
| Element | Value |
|---|---|
| Construction | median price displaced forward by ½·P |
| Property | known ½·P bars ahead; never repaints |
| Signal | price/FLD crossing (up = buy, down = sell, in context) |
| Ruler | target = crossing + (crossing − trough); exact on the pure cycle |
| Source | Cycles Course ≈1973 + Hickson tradition — not the 1970 book |
Enlaces
- After the book — the post-1970 path
- Phasing analysis — where the period comes from
- The synchronicity trick — the short cycles' FLD
- Valid trend line — the book's signal
- Action signal — the family of objective signals