Average Directional Movement Index

Average Directional Movement Index Technical Indicator (ADX) helps to determine if there is a price trend. It was developed and described in detail by Welles Wilder in his book "New concepts in technical trading systems".

The simplest trading method based on the system of directional movement implies comparison of two direction indicators: the 14-period +DI one and the 14-period -DI. To do this, one either puts the charts of indicators one on top of the other, or +DI is subtracted from -DI. W. Wilder recommends buying when +DI is higher than -DI, and selling when +DI sinks lower than -DI.

To these simple commercial rules Wells Wilder added "a rule of points of extremum". It is used to eliminate false signals and decrease the number of deals. According to the principle of points of extremum, the "point of extremum" is the point when +DI and -DI cross each other. If +DI raises higher than -DI, this point will be the maximum price of the day when they cross. If +DI is lower than -DI, this point will be the minimum price of the day they cross.

The point of extremum is used then as the market entry level. Thus, after the signal to buy (+DI is higher than -DI) one must wait till the price has exceeded the point of extremum, and only then buy. However, if the price fails to exceed the level of the point of extremum, one should retain the short position.

ADX = SUM[(+DI-(-DI))/(+DI+(-DI)), N]/N

N — the number of periods used in the calculation.

A number of different trading systems have developed around Directional Movement. The following rules are based on the system presented by Dr Alexander Elder in Trading for a Living:

Go long when +DI is above -DI and either:

  • ADX rises while +DI and ADX are above -DI; or
  • ADX turns up from below +DI and -DI.
Exit when +DI crosses below -DI.

Go short when -DI is above +DI and either:

  • ADX rises while -DI and ADX are above +DI; or
  • ADX turns up from below +DI and -DI.
Exit when -DI crosses below +DI.
Use stop-losses at all times.


Declining ADX shows that the market is losing direction. When ADX falls below both +DI and -DI it signals a lifeless market. Do not trade with DMS until ADX has clearly turned off the bottom. Dr Elder suggests waiting until ADX rises 4 steps off its low (e.g. ADX rises to 19 from a low of 15). The longer that ADX has remained below both +DI and -DI the stronger the subsequent trend is likely to be.
When ADX rises above both +DI and -DI it signals that the market is becoming overheated. Take profits when ADX turns downwards from above +DI and -DI.