Momentum and RSI

RSI is an often used indicator in technical analysis. RSI means Relative Strength Index, and it measures how well a stock has performed compared to itself. The figure is calculated by looking at the strength of days with rising prices compared to strength of days with falling prices over a certain period of time and it gets a value between 0 and 100.

A stock that has risen a lot compared to reactions back during this time, will have high RSI. Similarly a stock that has fallen a lot compared to reactions back, will have low RSI. RSI is used as an indicator of whether a stock is oversold or overbought, and if it has positive momentum or negative momentum.

RSI can indicate that:

• This stock has risen a lot in a short time. Optimism is increasing and further rise is indicated.
• This stock has fallen a lot in a short time. The investors are becoming more pessimistic and will continue to reduce prices to get out of the stock.

Many investors also think that RSI indicates whether a stock has risen or fallen too much and will react back. Investtech’s research shows that this overbought and oversold interpretation is statistically not true.

Read the research report on RSI here.

RSI as overbought/oversold indicator

A stock is overbought when it has risen a lot in a short time, without any significant reactions back during the time period. The idea is that it has risen too much and will have a reaction back soon, indicating that it is time to sell the stock. Similarly a stock is oversold when it has fallen a lot in a short time. This may indicate that it will have a reaction up soon and should be bought before then. See example below.

RSI as momentum indicator

RSI is also used as a momentum indicator. The idea is that major price movements indicate that the investors as a group are in motion. It is thought necessary to join the early movements, as even more investors will join later and drive the price further in the same direction. See example below.