Williams Fractal

What is a Williams Fractal?

A Williams Fractal is a five-bar swing marker popularized by Bill Williams in his Trading Chaos work. An up fractal prints on a bar whose high stands above the highs of the two bars on each side; a down fractal prints where a bar's low sits below the two lows on each side. It is among the simplest widely used objective definitions of a swing high or low: no subjective drawing, just a local extreme over five bars. Implementations differ slightly on how ties are handled, with strict inequality the common default.

Two properties define how fractals behave in practice. First, confirmation lags by two bars: the pattern cannot exist until the two right-hand bars have closed, so the marker always appears in the past. Second, fractals are frequent, since a two-bar flank is a low hurdle; in Williams' own system they were therefore filtered by the Alligator and traded only as breakouts in the trend direction. Beyond that origin, the fractal has become a general-purpose building block: a mechanical swing definition feeding structure logic, trailing stops, and support and resistance levels.

How to identify a Williams Fractal

The definition is mechanical, which is exactly its appeal. A standard fractal needs five completed bars.

1. 1Take a candidate bar plus the two bars before it and the two bars after it.
2. 2Up fractal: the candidate's high is higher than all four neighboring highs. Down fractal: the candidate's low is lower than all four neighboring lows. A single bar can qualify as both.
3. 3Wait for confirmation: the two right-hand bars must close first, so a fractal is only known two bars after the extreme actually printed. Anything drawn earlier is provisional.
4. 4Adjust conventions as needed: some versions accept equal highs or lows on the flanks, and widening the flanks beyond two bars produces fewer, more significant swings at the cost of later confirmation (this is the pivot strength parameter).

How traders use it

• As the swing vocabulary for structure logic: the most recent up and down fractals define the swing points that break of structure and change-of-character rules are evaluated against. Many structure tools are fractal detection under the hood.
• As breakout triggers, the original use: Williams placed buy stops just above the latest up fractal when it formed above the Alligator's teeth, ignoring fractal signals on the wrong side of that line. Later tools generalize the idea into a stair-stepped breakout channel built from successive fractal levels.
• As trailing stop anchors: in an uptrend, trail the stop under each newly confirmed down fractal, a mechanical form of the structure stop.
• As resting-liquidity markers: untouched fractal highs and lows are local extremes where stops tend to accumulate, so some traders track which fractals have been swept and which remain open as potential targets.

Williams Fractal vs related concepts