The Commodity Channel Index is a tool developed by Donald Lambert to measure the point at which cyclical price reversals for a given asset can be expected. One of the fundamental assumptions behind the CCI is that price trends reverse at regular intervals within an asset, allowing investors to take the appropriate action when the CCI indicates that one of those cyclical reversals is imminent.
The CCI is calculated first by averaging the high, low and closing prices into a measure called the True Price, or TP. A 20-period moving average of the TP becomes the Simple Moving Average of the True Price, or SMATP. A standard deviation of the difference between SMATP and TP over twenty periods is also taken. The difference between TP and SMATP is then divided by the product of this standard deviation and a constant value of .015 to produce the CCI.
The constant value of .015 ensures that the majority of CCI values fall between 100 and -100. In the case that the absolute value of CCI exceeds 100, Lambert’s theory indicates that the market is approaching one of its cyclical reversals, and that traders should take the appropriate action. The CCI also indicates overbought and oversold levels, which are any levels whose absolute value exceeds 100. If the CCI moves outside of the -100 to 100 range and then returns, either a buy or sell signal is generated, depending on whether the CCI was below -100 (oversold) or above 100 (overbought.)