Accelerator Oscillator (AC)

The Accelerator Oscillator (AC) measures the acceleration or deceleration of the market's driving force. Developed by Bill Williams, it is derived from the Awesome Oscillator (AO) and represents the difference between AO and its 5-period SMA. AC detects changes in momentum before they appear in price.

AC is calculated from the Awesome Oscillator:

AO = SMA(Midpoint, 5) - SMA(Midpoint, 34)
AC = AO - SMA(AO, 5)
Midpoint = (High + Low) / 2

AC oscillates around zero. When AC changes color (from red to green or vice versa), it signals a change in the rate of momentum change.

• Above 0 — The driving force is accelerating upward
• Below 0 — The driving force is accelerating downward
• Rising AC — Momentum is accelerating (regardless of sign)
• Falling AC — Momentum is decelerating (regardless of sign)
• No user-configurable parameters — Uses fixed SMA(5) and SMA(34)

Buy signals

• AC crosses above 0 (acceleration turns bullish)
• Two consecutive green (rising) bars above zero line
• AC diverges bullishly from price

Sell signals

• AC crosses below 0 (acceleration turns bearish)
• Two consecutive red (falling) bars below zero line
• AC diverges bearishly from price

| Parameter | Default | Description | |-----------|---------|-------------| | — | — | No user-configurable parameters |

| Condition | Meaning | |-----------|---------| | AC > 0 | Bullish acceleration | | AC < 0 | Bearish acceleration | | AC cross_over 0 | Acceleration turned bullish | | AC cross_under 0 | Acceleration turned bearish |

• AC changes direction before AO, and AO changes before price — making AC a leading indicator
• Part of the Bill Williams trading system (used with Alligator, AO, and Fractals)
• Green bars (AC rising) above zero are the strongest bullish confirmation
• Red bars (AC falling) below zero are the strongest bearish confirmation
• Avoid trading when AC and AO give conflicting signals