From: Tommy C.

How is the McClellan Oscillator determined each day?
I've noticed on rare occasions that some days when
the market is up (or down) that the Oscillator
moves in the opposite direction.

Thanks,
Tommy

~~~Christopher's Response~~~

Tommy,

The McClellan Oscillator is a breadth indicator derived
from each day's net advances, the number of advancing
issues less the number of declining issues. Subtracting
the 19-day exponential moving average from the 39-day
exponential moving average of net advances forms the
oscillator.

Similar to MACD, this Oscillator is a momentum
indicator that is applied to the advance/decline statistics.
When the 19-day EMA (shorter moving average) moves above the
39-day (longer moving average) EMA, it signals that advances
are gaining the upper hand. Conversely, when the 19-day EMA
declines below the 39-day EMA, it signals that declining
issues are dominant. As a momentum indicator, the McClellan
attempts to anticipate positive and negative
changes in the AD statistics for market timing.

Buy and sell signals are generated as well as overbought
and oversold readings. Usually, readings above +100 are
considered overbought and below -100 oversold. Overbought
and oversold readings may vary among indices and historical
precedent. Buy signals are generated when the oscillator
advances from oversold levels to positive territory. Sell
signals are generated on declines from overbought to negative
territory. Traders may also look for positive or negative
divergences to time their trades. A series of rising troughs
would denote strength, while a series of declining peaks
denote weakness.