The parabolic SAR is a technical indicator used to determine the price direction of an asset, as well as draw attention to when the price direction is changing. Sometimes known as the “stop and reversal system,” the parabolic SAR was developed by J. Welles Wilder Jr., creator of the relative strength index (RSI).1
On a chart, the indicator appears as a series of dots placed either above or below the price bars. A dot below the price is deemed to be a bullish signal. Conversely, a dot above the price is used to illustrate that the bears are in control and that the momentum is likely to remain downward. When the dots flip, it indicates that a potential change in price direction is under way. For example, if the dots are above the price, when they flip below the price, it could signal a further rise in price.
As the price of a stock rises, the dots will rise as well, first slowly and then picking up speed and accelerating with the trend. The SAR starts to move a little faster as the trend develops, and the dots soon catch up to the price.
The following chart shows that the indicator works well for capturing profits during a trend, but it can lead to many false signals when the price moves sideways or is trading in a choppy market. The indicator would have kept the trader in the trade while the price rose. When the price is moving sideways, the trader should expect more losses and/or small profits.