The GMMA is a very useful technical indicator for long term investors. I am using this indicator together with the trend lines and simple moving averages for all my analysis on stocks.
If you are not sure whether to hold a particular stocks and you need confirmation, GMMA is a good indicator to check whether the long term investors are still holding the stock by looking at the "green lines". For a long term bullish trend, the green lines have to be upward sloping, the lines must not compressed and the red lines (short term speculators) must be bouncing off from the green lines.