Bill Williams Alligator Indicator: Trading the Market Phases
The Anatomy of the Alligator: Jaw, Teeth, and Lips
Developed by Bill Williams, the Alligator indicator is a trend-following tool that uses three smoothed moving averages to visualize market dynamics. Each line represents a different timeframe and is metaphorically linked to the anatomy of an alligator.
- The Jaw (Blue Line): A 13-period SMA, shifted 8 bars into the future. It represents the 'Balance Line' for the long-term trend.
- The Teeth (Red Line): An 8-period SMA, shifted 5 bars into the future. It represents the intermediate-term balance.
- The Lips (Green Line): A 5-period SMA, shifted 3 bars into the future. It represents the short-term sentiment.
Metaphorical Analysis: The Sleeping Alligator
The power of the Alligator lies in its ability to identify when a market is transitioning from a range to a trend. Bill Williams described this using the metaphor of an alligator's hunger cycle.
The Sleep: When the three lines are intertwined or very close together, the 'Alligator is sleeping.' This indicates a range-bound, low-volatility market. Professional traders stay on the sidelines during this phase because 'the longer the alligator sleeps, the hungrier it becomes' when it finally wakes up.
Alligator Trading Rules
Primary Signal: Lines spreading apart (Awakening)
Bullish: Lips > Teeth > Jaw (Mouth opening up)
Bearish: Lips < Teeth < Jaw (Mouth opening down)
Avoid: Trading when lines are intertwined (Sleeping)
Exit: Close trade when lines begin to cross back
Stop-Loss: Place beyond the Blue Jaw line
Awakening and Feeding: Strategy Execution
The Awakening: When the lines begin to spread apart and move in one direction, the Alligator has woken up. If the Green (Lips) is above Red (Teeth), and Red is above Blue (Jaw), the Alligator is opening its mouth to the upside—a bullish signal.
The Feeding: As long as the lines remain separated and sloped, the Alligator is 'feeding' on a trend. You should stay in the trade as long as the price remains outside the 'mouth'. When the lines start to converge again, the Alligator is full and ready to go back to sleep, signaling it's time to take profits.
Filtering: Combining with Fractals
Bill Williams rarely used the Alligator in isolation. In his 'New Dimensions in Market Trading', he recommends only taking an Alligator entry if it is confirmed by a Fractal breakout above or below the Alligator's mouth. This ensures you are entering a move that has genuine structural momentum.