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Parabolic Stop and Reverse (SAR) is a technical indicator utilised to evaluate trend direction and identify potential reversal points.
Displayed as a series of dots positioned above or below price bars on a chart, it provides a clear visual read on market control.
This article breaks down how the Parabolic Stop and Reverse indicator functions and its underlying calculations.
Key Takeaways
- The indicator dots accelerate as a trend matures, moving closer to the price action during a strong, sustained move than at its inception.
- The calculation relies on three main components: the previous SAR value, the acceleration factor, and the extreme point.
- A single dot breaking the prevailing colour configuration is often monitored as an early warning sign of a shifting trend.
- Traders frequently utilise the dot levels as dynamic trailing stop-losses.
- In sideways or range-bound markets, the indicator can generate frequent false signals (whipsaws).
What is Parabolic SAR?
Parabolic Stop and Reverse (SAR) helps determine the direction of a price trend and identify potential reversal points.
Developed by J. Welles Wilder Jr., it appears on a price chart as a series of dots positioned either above or below the price bars. When the dots sit below the price, they indicate buyers are in control during an uptrend, whereas dots above the price signal that sellers are driving a downtrend.
How Parabolic SAR Works
On a price chart, the Parabolic SAR appears as a sequence of dots tracking above or below the price candles. When the dots sit underneath the price action, the indicator signals that buyers are maintaining control in an ongoing uptrend.
When the dots sit above the price, they indicate sellers control the market during a downtrend.
The critical event occurs when the dots shift sides, moving from below the price to above it, or vice versa. This stop-and-reverse transition suggests that the existing trend may be losing momentum, flagging a potential trend change.
The dots progress non-linearly. They advance slowly at the start of a trend and accelerate as momentum builds, curving closer to the price pattern like a parabola.
Read More: What are Stock Appreciation Rights (SARs)
The Formula Behind Parabolic SAR
The Parabolic SAR calculates each subsequent point using:
SAR (next) = Previous SAR + AF × (EP − Previous SAR)
Core Components
- Previous SAR: The SAR value calculated for the preceding period.
- Acceleration Factor (AF): Controls how quickly SAR moves toward the extreme point. It typically starts at 0.02, increases by 0.02 when a new extreme point is reached, and is capped at 0.20.
- Extreme Point (EP): The highest high during an uptrend or the lowest low during a downtrend.
Constraint Rules
The formula also follows two key constraints:
- Uptrend: The next SAR cannot exceed the lows of today or the previous day. If it does, it is set to the lower of the two lows.
- Downtrend: The next SAR cannot fall below the highs of today or the previous day. If it does, it is set to the higher of the two highs.
Reading Parabolic SAR Signals on a Chart
| Dot Position | Market Signal | Trader Action |
| Below the price | Uptrend / bullish | Hold or evaluate long positions |
| Above the price | Downtrend / bearish | Hold or evaluate short positions |
| Flips from below to above | Potential bearish reversal | Exit long, consider short parameters |
| Flips from above to below | Potential bullish reversal | Exit short, consider long parameters |
How Parabolic SAR is Used Beyond Trend Spotting
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Trailing Stop-Loss Management: Acting as a dynamic level that adjusts with the price structure to protect open profits.
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Trade Timing: Helping identify structural shifts to manage entries or exits.
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Dynamic Support and Resistance: Serving as structural reference lines during active trends.
Pros and Cons of Parabolic SAR
Pros
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Simple, visual interpretation without complex mental math.
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Systematic, rule-based output that minimises emotional decision-making.
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Effective performance during clear, extended trending phases.
Cons
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Susceptible to frequent false signals (whipsawing) during choppy or range-bound market phases.
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Generates continuous signals regardless of whether an actual market trend is present.
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Vulnerability to sudden volatility spikes or news-driven gaps that cause rapid dot flipping.
Pairing Parabolic SAR With Other Tools
To mitigate false signals, technical analysts rarely utilise the Parabolic SAR in isolation. Common complementary tools include:
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Moving Averages: To establish primary trend direction.
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Average Directional Index (ADX): To confirm whether a trend possesses sufficient strength before acting on a SAR signal.
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Momentum Oscillators: Such as the Relative Strength Index (RSI) or Stochastic oscillators to provide secondary validation.
Conclusion
The Parabolic SAR works well when prices move in a clear upward or downward direction, as the SAR dots can help traders identify potential entry, exit and reversal points. The indicator can generate frequent false signals when the market moves sideways or becomes highly volatile.
For this reason, Parabolic SAR is generally more effective when combined with trend-confirming tools such as moving averages, ADX or price action analysis. Using multiple indicators adds context and helps traders assess whether a potential trend is strong enough to support a trading decision.
