The McClellan Oscillator uses advance/decline data to calculate the strength or weakness of a move from a breadth standpoint. The value will vary from provider to provider as there are often slight differences in advance/decline data. Worden Bros. is one data provider I use. Their measure of the McClellan Oscillator hit -381.49 on Wednesday. This is the lowest reading since they began tracking advance/decline data in 1986. (Others I look at are low but not quite all-time lows.) Below is a chart of the McClellan Oscillator over the entire data period.
![](https://1.bp.blogspot.com/_931wANibTqw/SumKoA8BwgI/AAAAAAAABaQ/uCrMrtnSqfI/s800/2009-10-29+png1.png)
One notable about this chart is that breadth readings have become more extreme over time. Whereas moves above 100 and below -100 were rare from ’86 – ’93, they are fairly ordinary today.
For more information on the McClellan Oscillator you may visit the link below: