What it does
Bill Williams' Accelerator Oscillator (AC) measures whether momentum is speeding up or slowing down. It is computed as the Awesome Oscillator minus a 5-period SMA of the Awesome Oscillator, plotted as a histogram colored by whether each bar is higher (green) or lower (red) than the previous one. The idea is that acceleration changes direction before momentum, and momentum before price.
How to add it
Click Indicators (ƒx) in the header.
Search “Accelerator Oscillator” and click the result.
Hover its legend row and click the gear to open settings.
How traders use it
- Color matters more than the zero line: consecutive green bars show building bullish acceleration, consecutive red bars show bearish acceleration.
- Classic entry filter: only buy when AC prints green (traditionally two green bars above zero, or three below zero for a counter-zone long); mirror for shorts.
- AC crossing zero is not itself a signal in Williams' method; use it with fractal breakouts and the Alligator for the full setup.
- Fading acceleration (shrinking bars) while price pushes to new extremes warns the move is running out of fuel.
- Use it to time entries within a trend defined by a slower tool rather than as a standalone system.
Inputs
This indicator has no configurable inputs — it works out of the box.
Plots & styling
| Plot | Style | Default color |
|---|---|---|
| AC | histogram | #000080 |
Every plot's color, line width and visibility can be changed on the Style tab. Precision (default 4 decimals), price-scale labels and status-line values are configurable at the bottom of the Style tab.
Tips
- The pane keeps its height in saved layouts, so size it once and it survives reloads.
- Resize the pane by dragging its divider; collapse it from the legend row when you need the space back.
- Use Add to favorites in the legend menu; starred studies surface at the top of the picker.
Watch out for
- As a second derivative of price it is very noisy; single-bar color flips are frequent and meaningless in quiet markets.
- Signals need trend context; traded alone, AC produces many whipsaws in ranges.