Lesson 22 – The Relative Strength Index

In our last lesson we looked at 3 different ways to trade the MACD indicator. In this lesson we are going to look at a class of indicators which are known as Oscillators with a look at how to trade one of the more popular Oscillators the Relative Strength Index (RSI).

An oscillator is a leading technical indicator which fluctuates above and below a center line and normally has upper and lower bands which indicate overbought and oversold conditions in the market (an exception to this would be the MACD which is an Oscillator as well). One of the most popular Oscillators outside of the MACD which we have already gone over is the Relative Strength Index (RSI) which is where we will start our discussion.

The RSI is best described as an indicator which represents the momentum in a particular financial instrument as well as when it is reaching extreme levels to the upside (referred to as overbought) or downside (referred to as oversold) and is therefore due for a reversal. The indicator accomplishes this through a formula which compares the size of recent gains for a particular financial instrument to the size of recent losses, the results of which are plotted as a line which fluctuates between 0 and 100. Bands are then placed at 70 which is considered an extreme level to the upside, and 30 which is considered an extreme level to the downside.

Example of the RSI

The first and most popular way that traders use the RSI is to identify and potentially trade overbought and oversold areas in the market. Because of the way the RSI is constructed a reading of 100 would indicate zero losses in the dataset that you are analyzing, and a reading of zero would indicate zero gains, both of which would be a very rare occurrence. As such James Wilder who developed the indicator chose the levels of 70 to identify overbought conditions and 30 to identify oversold conditions. When the RSI line trades above the 70 line this is seen by traders as a sign the market is becoming overextended to the upside. Conversely when the market trades below the 30 line this is seen by traders as a sign that the market is becoming over extended to the downside. As such traders will look for opportunities to go long when the RSI is below 30 and opportunities to go short when it is above 70. As with all indicators however this is best done when other parts of a trader’s analysis line up with the indicator.

Example of RSI Showing Overbought and Oversold

A second way that traders look to use the RSI is to look for divergences between the RSI and the financial instrument that they are analyzing, particularly when these divergences occur after overbought or oversold conditions in the market. These divergences can act as a sign that a move is loosing momentum and often occur before reversals in the market. As such traders will watch for divergences as a potential opportunity to trade a reversal in the stock, futures or forex markets or to enter in the direction of a trend on a pullback.

Example of RSI Divergence

The third way that traders look to use the RSI is to identify bullish and bearish changes in the market by watching the RSI line for when it crosses above or below the center line. Although traders will not normally look to trade the crossover it can be used as confirmation for trades based on other methods. As you can see in the chart below, the RSI crossover was a great confirmation of the head and shoulders top, a pattern which we learned about in previous lessons and that occurred recently in the EUR/USD.

Example of the RSI Centerline Crossover