The 'parabolic SAR' is an indicator that we can safely say is a very useful and accurate tool during a trending period, but is otherwise absolutely useless.
This time/price system was first introduced by J.Welles Wilder in his acclaimed book "New Concepts in Technical
Trading Systems" (1978). SAR stands for 'stop and reverse' and the term 'parabolic' comes from the shape of the curve (resembling a parabola) created on the technical chart.
Sometimes called a reversal system, the Parabolic SAR allows the investor to follow the dots in either an upward or downward trend until SAR is reached and the trend reverses. It is primarily used in trending markets and is based on always having a position in the market. The indicator may also be used to determine stop points and to estimate when to reverse a position and take a trade in the opposite direction.
The first entry point on the buy side occurs when the most recent high price of an issue has been broken and it is at this time that the SAR is placed at the most recent low price. As the price of the
stock rises, the dots will rise as well, first slowly and then picking up speed and accelerating with the trend. It is understood that Wilder built-in this accelerating system to allow the investor to watch the trend develop and establish itself. The SAR starts to move a little faster as the trend develops and the dots soon catch up to the price action of the issue you are following. As you can see in the charts below, the system, as I have mentioned before, works extremely well in markets with a dominant trend markets and fails miserably in horizontal or choppy markets.
Now, given that sectors and the stock issues in those sectors will never trend immediately from any position on a chart, they will eventually develop. The accelerating system is extremely valuable because it allows for the investor to get into the issue after they see the dots move closer to the price action, thus confirming that the trend is established. One of the tricks of the trade is the use of
stop-loss orders using the development of the SAR to lock-in profits that have been realized on paper in an upward trend. You can also see that those
professionals that
short the market will use this system to help determine the time to cover their short positions.
This
trading system is extremely mechanical, and therefore takes out all of the human emotion that can get many new investors as well as the occasional veteran in big trouble. "Never fall in love with a stock, because it will never love you back." With Parabolic SAR, all the emotion is taken out of the equation. The investor becomes disciplined and a more consistent trading pattern is achieved. The downside to this system is that most stocks that we follow do not develop consistent trends and therefore create a herky-jerky SAR that is somewhat predominant in our charts, which makes it difficult to enter and exit with consistent profits.