Directional movement

Directional Movement

Directional movement is a system for providing trading signals to be used for price breaks from a trading range. The system involves 5 indicators which are the Directional Movement Index (DX), the plus Directional Indicator (+DI), the minus Directional Indicator (-DI), the average Directional Movement (ADX) and the Directional movement rating (ADXR). The system was developed J. Welles Wilder and is explained thoroughly in his book, New Concepts in Technical Trading Systems .

The basic Directional Movement Trading system involves plotting the 14day +DI and the 14 day -DI on top of each other. When the +DI rises above the -DI, it is a bullish signal. A bearish signal occurs when the +DI falls below the -DI. To avoid whipsaws, Wilder identifies a trigger point to be the extreme price on the day the lines cross. If you have received a buy signal, you would wait for the security to rise above the extreme price (the high price on the day the lines crossed). If you are waiting for a sell signal the extreme point is then defined as the low price on the day's the line cross.

The system works best according to Wilder on securities that have an ADXR value above 25.

A good variation of the Directional Movement system is to plot the difference between the positive Directional Indicator and the negative Directional Indicator. The result is plotted on the chart below and can be used to look for divergences between price and the indicator.

To the right technical studies are examined in more detail to provide a sense of conformational evidence for traders of the critical day. Click on any of the terms to take a closer look at a technical discussion on that topic. All formations, patterns, indicators and technical tools fail at various times and so should only be used to build a body of evidence in forming a trading decision rather than being solely relied upon. There are a number of valuable studies that lead to intuitive understandings about price and volume but a strong compliment to technical analysis is an understanding of the trends and changes in the fundamentals and economic activity that ultimately lead valuation levels in the markets.

Walk through a critical day

The graphs show a price plot of the Dow Jones Industrials from Sept 28/00 to early November. The First graph ends on November 3/00, two days before an upcoming critical day on November 7/00. Our members looking at the market are expecting a trend reversal to occur due to the high rate of success in our research. Ideally a member will be using their own skills to judge the supply and demand changes, using technical and fundamental indications to confirm suspicions of a reversal, and trade accordingly.
On the second graph we see that the price action on November 6 was a bullish day, reversing the short trend so that the short trend leading into the critical day is now up. A critical day is an expectation of a reversal of the short trend that immediately precedes the critical day. In the case of the November 7 signal, given to members 3 days before, is an indication that the upward moving trend, recognized at the close of November 6 is expected to reverse direction.
On the third graph we can see that November 7 was a low volatility after a large gain on November 6 of about 160 points for the Dow Jones Industrials. The subsequent move over the three days following the November 7 signal saw the Dow Jones Industrials fall 376 points. The next day, November 13, the Dow Jones Industrials lost an additional 83 points with intra-day low a full 609 point loss since the open on the critical day.

Most recent signals

A closer view of the most recent signals. You can see the short trend immediately prior to a successful critical day, reverses coming away from the critical day. Often a failed critical day will indicate a stronger bias in the market for continuation of the trend that was in place prior to the critical day. A failed signal can therefore provide as much information and opportunity as a successful one. Take a look at tech studies to develop a sense of trend reversals and use.

The Directional Movement Index, DMI, is an effective and frequently used trend indicator. This system was designed by Welles Wilder Jr. and is made up of three lines:

In the example above two clear buy signals have been generated. The first could have been ignored because ADX was very close to 25 - a potential danger signal. The second was perhaps more significant, even though ADX was trending downwards. It did provide a clear indication of the beginning of a very strong move in this market.

Buy and sell signals are given when +DI and -DI cross. The time periods most commonly used in the complex formula are 10 or 14 days.

Generally speaking, the two main buy and sell signals generated by DMI are as follows:

Wilder himself developed a refinement to take care of whipsawing (when the DI lines cross back and forth over a short period, providing unreliable signals). He called it his Extreme Point Rule.

The Extreme Point Rule is derived by noting the high or low point on the day when the +DI and the -DI cross one another. +DI determines the high or low point (if +DI is above -DI the Extreme Point is the high of the day, if +DI is below -DI, the Extreme Point is the low for the day).

The extreme point is then used for the actual buy or sell signal. For example, if the price once again rises above the Extreme Point price level you have a buy signal. If the price fails to rise above the extreme point, you should continue to stand aside. The converse holds true for sell signals.

An additional indicator, the average directional movement index rating (ADXR), was created by Wilder as a measuring tool for the strength of ADX. ADXR is the average of the current ADX and the ADX 14 days ago. ADXR is typically plotted alongside ADX on the same chart.

J. Welles Wilder developed the Average Directional Index (ADX) to evaluate the strength of a current trend, be it up or down. It's important to determine whether the market is trending or trading (moving sideways), because certain indicators give more useful results depending on the market doing one or the other.

The ADX is an oscillator that fluctuates between 0 and 100. Even though the scale is from 0 to 100, readings above 60 are relatively rare. Low readings, below 20, indicate a weak trend and high readings, above 40, indicate a strong trend. The indicator does not grade the trend as bullish or bearish, but merely assesses the strength of the current trend. A reading above 40 can indicate a strong downtrend as well as a strong uptrend.

ADX can also be used to identify potential changes in a market from trending to non-trending. When ADX begins to strengthen from below 20 and moves above 20, it is a sign that the trading range is ending and a trend is developing.

JC Penney
Co, Inc. (JCP) ADX strong trend example chart from StockCharts.com

When ADX begins to weaken from above 40 and moves below 40, it is a sign that the current trend is losing strength and a trading range could develop.

Intel Corp. (INTC)
ADX weak trend example chart from StockCharts.com

Positive/Negative Directional Indicators

The ADX is derived from two other indicators, also developed by Wilder, called the Positive Directional Indicator (sometimes written +DI) and the Negative Directional Indicator (-DI).

When the ADX Indicator is selected, SharpCharts plots the Positive Directional Indicator (+DI), Negative Directional Indicator (-DI) and Average Directional Index (ADX). With the Red, White and Green color scheme on SharpCharts, ADX is the thick black line with less fluctuation, +DI is green and -DI is red. +DI measures the force of the up moves and -DI measures the force of the down moves over a set period. The default setting is 14 periods, but users are encouraged to modify these settings according to their personal preferences.

In its most basic form, buy and sell signals can be generated by +DI/-DI crosses. A buy signal occurs when +DI moves above -DI and a sell signal when -DI moves above the +DI. Be careful, though; when a security is in a trading range, this system may produce many whipsaws. As with most technical indicators, +DI/-DI crosses should be used in conjunction with other aspects of technical analysis.

The ADX combines +DI with -DI, and then smooths the data with a moving average to provide a measurement of trend strength. Because it uses both +DI and -DI, ADX does not offer any indication of trend direction, just strength. Generally, readings above 40 indicate a strong trend and readings below 20 a weak trend. To catch a trend in its early stages, you might look for stocks with ADX that advances above 20. Conversely, an ADX decline from above 40 might signal that the current trend is weakening and a trading range is developing.

The Average Directional Index (ADX) and SharpCharts

With SharpCharts, you can plot the +DI/-DI using the Wilder's DMI (ADX) indicator above, below, or behind the price plot chart. The Parameters text box controls the number of periods used to calculate the ADX, with the default being 14. The Position drop-down menu controls the positioning of the indicator.

Bear in mind that increasing the number of periods will smooth the ADX line (making it less volatile), and display more significant readings. The readings, however, will present more of a lag. For example, if charting 30 periods, readings over 40 become stronger indicators of a trend. However, the trend may have already started and could have been caught earlier less periods were used.

More on ADX can be found in Wilder's book, New Concepts In Technical Trading Systems, written in 1978. Wilder's indicators remain some of the best and most popular indicators today.