Key Takeaways
- Momentum indicator using 19- and 39-day EMAs.
- Signals bullish/bearish trends via zero line cross.
- Detects overbought, oversold, and divergence conditions.
What is McClellan Oscillator?
The McClellan Oscillator is a momentum indicator that measures market breadth by calculating the difference between the 19-day and 39-day exponential moving averages (EMAs) of Net Advances—advancing issues minus declining issues—primarily on the NYSE. It oscillates around a zero line, helping traders identify trend strength, overbought or oversold conditions, and potential reversals, similar to the MACD indicator.
Developed by Sherman and Marian McClellan in 1969, this tool provides insight into market momentum beyond price movements, enhancing your trading decisions based on breadth data.
Key Characteristics
The McClellan Oscillator offers clear, actionable signals through its calculation method and interpretation:
- Momentum Measurement: Uses the difference between short-term (19-day) and long-term (39-day) EMAs of Net Advances for momentum assessment.
- Oscillation Around Zero: Values above zero indicate bullish momentum; below zero signal bearish momentum.
- Overbought/Oversold Levels: Extreme readings suggest potential reversals, similar to other momentum tools.
- Divergence Detection: Helps identify divergences between price trends and market breadth.
- Calculation Method: Employs data smoothing techniques through EMAs for noise reduction.
How It Works
The oscillator calculates two EMAs of Net Advances—one short-term (19-day) and one long-term (39-day)—and subtracts the long-term from the short-term to gauge momentum shifts. When the oscillator crosses above zero, it signals strengthening breadth and potential buy opportunities; crossing below zero indicates weakening breadth and potential sell signals.
Traders often watch for divergence between the oscillator and price indexes like SPY or IVV, indicating weakening market participation despite price moves. This makes it a valuable complement to trend-following tools such as the Parabolic Indicator.
Examples and Use Cases
The McClellan Oscillator is widely used for short- to intermediate-term trading strategies and market health analysis. Here are practical examples:
- Large-Cap Stocks: Investors tracking best large-cap stocks use the oscillator to confirm broad market participation in price rallies.
- ETFs: Traders applying it to ETFs like SPY and IVV monitor market breadth momentum for timing entries and exits.
- Broad Market Analysis: The oscillator’s signals assist in evaluating market-wide strength, complementing data from best ETFs and individual stock analysis.
Important Considerations
While the McClellan Oscillator offers valuable breadth momentum insights, it can produce false signals in sideways or low-volume markets. Confirming its signals with price action or volume is essential to avoid whipsaws common to momentum indicators like the MACD.
Its primary reliability lies with NYSE data, and it may be less effective in markets with fewer listed securities. Integrating it with other tools and maintaining awareness of market context will improve your trading outcomes.
Final Words
The McClellan Oscillator offers a clear view of market breadth momentum, signaling potential trend shifts and overbought or oversold conditions. Monitor its crossovers and divergences closely to time entries and exits more effectively. Consider integrating it with other indicators to confirm signals before making trading decisions.
Frequently Asked Questions
The McClellan Oscillator is a market breadth momentum indicator developed in 1969 that measures the difference between the 19-day and 39-day exponential moving averages of Net Advances on the NYSE. It helps traders identify momentum shifts, overbought or oversold conditions, and potential market reversals.
It is calculated by subtracting the 39-day EMA of Net Advances (advancing stocks minus declining stocks) from the 19-day EMA of Net Advances. This difference oscillates around zero to show short-term versus long-term market breadth momentum.
When the oscillator is above zero, it indicates that short-term breadth momentum is stronger than long-term, signaling bullish market conditions. Conversely, readings below zero suggest bearish momentum and potential sell signals.
Traders often use centerline crossovers to time entries and exits, confirm trends, and assess market health. For example, a move from negative to positive values can indicate a buy opportunity, while divergence between the oscillator and price can warn of reversals.
Breadth thrusts occur when the oscillator rapidly moves from oversold to overbought levels, such as jumping from -100 to +50 or higher within days. This signals strong bullish shifts and potential sustainable rallies.
Yes, it is often combined with the Summation Index, which is a cumulative total of the oscillator, to identify longer-term trends. Using it alongside price action and other market breadth tools improves reliability.
Like other momentum indicators, it can give false signals in sideways or ranging markets and divergences are not always reliable predictors. It works best with NYSE data and may be less effective in low-volume or non-equity markets.


