Trix was developed by Jack Hutson, editor of Stocks and Commodities Magazine. It is a 1 day rate of change of a triple exponentially smoothed moving average of closing prices. Applying a moving average of the Trix index, interpretation is then similar to MACD double line.

Triple smoothing involves repeating the exponetial smoothing process an additional two times. The result is a very smooth curve that filters out all cycles that are less than the time span chosen for the smoothing.