The Accelerator Oscillator (AC) is an indicator developed by Bill Williams that helps traders gauge changes in momentum. It is based on the Awesome Oscillator (AO)
and measures the difference between that indicator and its 5-period moving average, effectively showing how quickly the AO changes and predicting what it will do next. If the AC is in positive territory, the upward acceleration is likely to continue. If the AC is in negative territory, the downward acceleration is likely to continue. The bars in the histogram have 2 colors: red indicating a fall in price and green indicating a rise in price. Various specific buy and sell signals can be derived from the color of the bars and whether they are above or below the 0-line.