The Parabolic Time/Price System, developed by Welles
Wilder, is used to set trailing price stops and is usually referred to
as the "SAR" (stop-and-reversal). This indicator is explained thoroughly
in Wilder's book, New Concepts in Technical Trading Systems.
Interpretation
The Parabolic SAR provides excellent exit points.
You should close long positions when the price falls below the SAR and
close short positions when the price rises above the SAR.
If you are long (i.e., the price is above the SAR),
the SAR will move up every day, regardless of the direction the price is
moving. The amount the SAR moves up depends on the amount that prices
move.
Example
The following chart shows Compaq and its Parabolic
SAR.
You should be long when the SAR is below prices and
short when it is above prices.
The Parabolic SAR is plotted as shown in Wilder's
book. Each SAR stop level point is displayed on the day in which it is
in effect. Note that the SAR value is today's, not tomorrow's stop
level.
Calculation
It is beyond the scope of this book to explain the
calculation of the Parabolic SAR. Refer to Wilder's book New Concepts in
Technical Trading, for detailed calculation information.