The DeMarker indicator named after Thomas DeMark is a momentum oscillator very similar in nature to the Relative Strength Index (RSI) developed by Welles Wilder. By comparing inter-period price maxima and minima the DeMarker indicator attempts to gather information about price movements to help determine the underlying trend strength and identify over-bought/sold trade conditions. One of the main benefits of the DeMarker indicator is that they are less prone to distortions seen in indicators such as the Rate of Change (ROC), which are introduced by erratic price movements at the start of the analysis window which can cause sudden shifts in the momentum line even when the current price is little changed.

The default period for the calculation of the DeMarker indicator is 14. Traders should look to go long when the DeMarker falls below 30 during an up-trend and go short when DeMarker rises above 70 during a down-trend.