Parabolic SAR
Parabolic SAR
Developed by Welles Wilder, the Parabolic SAR refers to a price-and-time-based trading system. Wilder called this the “Parabolic Time/Price System.” SAR stands for “stop and reverse,” which is the actual indicator used in the system. SAR trails price as the trend extends over time. The indicator is below prices as they're rising and above prices as they're falling. In this regard, the indicator stops and reverses when the price trend reverses and breaks above or below the indicator.
Parabolic SAR calculation
Rising SAR
Prior SAR: The SAR value for the previous period.
Extreme Point (EP): The highest high of the current uptrend.
Acceleration Factor (AF): Starting at .02, AF increases by .02 each time the extreme point makes a new high. AF can reach a maximum of .20, no matter how long the uptrend extends.
Current SAR = Prior SAR - Prior AF(Prior SAR - Prior EP)
The Acceleration Factor is multiplied by the difference between the Prior period's SAR and the Extreme Point. This is then subtracted from the prior period's SAR. Note that SAR can never be below the prior two periods' highs. Should SAR be below one of those highs, use the highest of the two for SAR.
How to use Parabolic SAR
SAR follows price and can be considered a trend-following indicator. Once a downtrend reverses and starts up, SAR follows prices like a trailing stop. The stop continuously rises as long as the uptrend remains in place. In other words, SAR never decreases in an uptrend and continuously protects profits as prices advance. The indicator acts as a guard against the propensity to lower a stop-loss. Once price stops rising and reverses below SAR, a downtrend starts, with SAR above the price. SAR follows prices lower like a trailing stop. The stop continuously falls as long as the downtrend extends. Because SAR never rises in a downtrend, it continuously protects profits on short positions.
