McClellan Oscillator

Overview

The McClellan Oscillator applies a 19-day and 39-day EMA to the daily advance-decline difference, creating a momentum oscillator for market breadth that identifies overbought/oversold conditions at the index level. It is a staple tool for stock market analysts tracking the health of major indices. Use the McClellan Oscillator alongside the A/D Line and TRIN for a complete breadth picture.

How It Works

McClellan Oscillator = 19-day EMA of (Advances − Declines) − 39-day EMA of (Advances − Declines). Positive readings indicate breadth momentum is bullish; negative readings indicate bearish breadth momentum. Extreme positive readings (>100) or negative readings (<−100) signal potential turning points.

Key Signals

• McClellan Oscillator crossing above zero = bullish breadth thrust.
• McClellan Oscillator crossing below zero = bearish breadth deterioration.
• Readings above +100 = potentially overbought breadth (short-term pullback likely).
• Readings below −100 = potentially oversold breadth (bounce likely).

Common Mistakes

• Using the McClellan Oscillator for individual securities — it only measures broad market breadth.
• Treating extreme readings as immediate trade signals without waiting for a turn.
• Not using the cumulative McClellan Summation Index for longer-term context.