Overview

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 when prices are rising and above prices when prices are falling. In this regard, the indicator stops and reverses when the price trend reverses and breaks above or below the indicator.

Wilder introduced the Parabolic Time/Price System in his 1978 book, New Concepts in Technical Trading Systems. This book also includes RSI, Average True Range (ATR), and the Directional Movement Concept (ADX). Despite being developed before the computer age, Wilder's indicators have stood the test of time and remain extremely popular.

Description

Calculation of SAR is complex with if/then variables that make it difficult to put in a spreadsheet. These examples will provide a general idea of how SAR is calculated. Because the formulas for rising and falling SAR are different, it is easier to divide the calculation into two parts. The first calculation covers rising SAR and the second covers falling 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 and SAR is 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.