Composite & famousAwesome Oscillator · AO
Bill Williams' histogram of the gap between a fast and slow average of the median price.
Works in most conditionsEngine-computed on a fixed sample series
What it is
The Awesome Oscillator, created by Bill Williams, is a momentum indicator that measures whether short-term market drive is outrunning the broader trend by comparing a fast and a slow average of each bar's midpoint. It is drawn as a histogram of bars oscillating above and below a zero line, and it answers whether momentum right now is stronger or weaker than it has been over the recent past. Williams designed it as a straightforward gauge of market momentum to be used alongside his Alligator and Accelerator Oscillator. Because it compares a 5-period and a 34-period average, it effectively contrasts the immediate five bars with roughly the last seven weeks of daily data, revealing shifts in the balance of momentum. It is a cornerstone of the Bill Williams trading system.
How it's calculated
The Awesome Oscillator is the difference between a 5-period simple moving average and a 34-period simple moving average, both computed on the bar's median price, which is the high plus the low divided by two. Using the median price rather than the close is a deliberate choice that captures the bar's center of activity. The 5-period average represents recent momentum and the 34-period average the broader momentum backdrop, so their difference is positive when the short term is stronger than the long term and negative when it is weaker. The result is plotted as a histogram around zero, and each bar is colored green if it is higher than the prior bar and red if it is lower. There are no other parameters; the 5 and 34 are fixed Williams values.
Reading it, step by step
Bars above zero mean short-term momentum is leading the broader market, and bars below zero mean it is lagging, so the zero line divides bullish from bearish momentum balance. The bar coloring — green for rising, red for falling — adds a second layer, showing whether momentum is building or fading at each step regardless of which side of zero it is on. Williams built three well-known patterns on this: the zero-line cross, when the histogram passes through zero and signals a change in momentum regime; the saucer, a quick color change on the same side of zero that marks a fast momentum shift for an early entry; and twin peaks, a divergence where two histogram peaks on the same side of zero disagree with price, warning of a reversal. Reading the AO means combining position relative to zero, the color sequence, and these three patterns. Extremes have no fixed level and must be judged against the instrument's own history.
Best timeframes and settings
The 5 and 34 parameters are Bill Williams' fixed values and are essentially never changed, since the whole system is calibrated around them. The AO applies to any timeframe, but because it uses a 34-period slow average it develops cleaner swings on intraday and swing timeframes where there is room for momentum to build; on very fast charts the histogram flickers and the saucer pattern in particular fires too often. As with the rest of the Williams toolkit, traders adjust sensitivity by changing timeframe rather than the parameters, moving up a timeframe for a calmer read. The daily chart is a common home for it in swing trading. Because the settings are locked, the responsiveness-versus-noise decision is really a timeframe decision.
When and where to use it
The AO is a momentum tool best used inside a trend context, ideally the Bill Williams framework where the Alligator confirms that a trend exists before AO signals are taken. It works on any liquid instrument and in any regime, but its signals are most reliable when a trend is underway rather than in a flat market where it whipsaws. Use it to gauge momentum, to time entries with the saucer, to confirm regime shifts with the zero cross, and to anticipate reversals with twin-peaks divergence. Avoid trading its signals in isolation in a choppy market, where the saucer especially misfires. It is designed as one layer of a multi-tool system, not a standalone trigger.
Strategies that use it
The saucer strategy takes the fastest entry: in an uptrend with the AO above zero, a red-red-green color sequence — a quick dip and recovery — signals a momentum saucer and a long entry, with the mirror for shorts below zero. The zero-cross strategy is slower and more conservative, buying when the histogram crosses from below to above zero and selling on the reverse, treating the cross as a confirmed momentum change. The twin-peaks strategy trades divergence: two peaks below zero where the second is higher than the first while price makes a lower low signals a bullish reversal, and the mirror above zero signals a bearish one. Williams intended all of these to be filtered by the Alligator so that entries are only taken when a trend is genuinely present, and the Accelerator Oscillator can add early confirmation.
Combining it with other indicators
The AO is built to work with its Bill Williams siblings — the Alligator supplies the trend filter and the Accelerator Oscillator supplies an earlier read on momentum's acceleration, so the three form a coherent system. Outside that family, the AO resembles a zero-line MACD histogram and can be used similarly, cross-checked against a standard MACD for confirmation. ADX complements it by confirming that a trend is present when the AO fires, filtering the saucer's false signals in flat markets. Because the AO gives momentum but not level context, support-and-resistance and trend structure help decide which signals to trust. The Elder-Ray Index, another momentum tool, offers a second view of buying and selling pressure to corroborate AO divergences.
Where it fails
As a difference of two moving averages, the AO lags and whipsaws in flat markets, and the saucer signal in particular fires frequently in chop, generating false entries when no trend is present. It carries no fixed overbought or oversold boundary, so judging when a reading is extreme requires comparison to the instrument's own recent history rather than an absolute threshold. Its divergence signals, like all divergences, can persist far longer than expected, so twin peaks can appear repeatedly before price actually turns. Because it lags, zero-line crosses arrive after momentum has already shifted. The defenses are to filter AO signals with the Alligator or ADX so they are only taken in a trend, to avoid the saucer in choppy markets, and to treat divergence as a warning to manage risk rather than an immediate reversal trigger.
A worked example
A stock is in a confirmed uptrend with the Alligator's lines fanned upward and the Awesome Oscillator histogram sitting above zero. Price pulls back for a few days, and the AO prints two red bars as momentum eases, then a green bar as the pullback ends — a saucer on the bullish side of zero. A Williams-system trader takes the long on that green bar near $75, reading the saucer as momentum resuming within an established uptrend that the Alligator confirms. Price advances to $82 over the next two weeks as the AO histogram climbs and stays green. Later, as price grinds to a marginal new high near $83, the AO makes a lower peak — a twin-peaks divergence — warning the trader that momentum is fading, so they tighten stops and exit near $82 as price rolls over. The saucer timed the entry and the twin peaks flagged the exit, both working because the trend context was in place.