Parabolic SAR: Trailing Stops and Trend Reversals
The Logic of Time and Price: Why PSAR is Unique
Developed by J. Welles Wilder Jr. (the creator of RSI and ATR), the Parabolic Stop and Reverse (SAR) is unique because it incorporates both price and time. While most indicators only update when price moves, PSAR dots 'move' closer to the price every single candle, even if the price stays flat.
The indicator is represented by dots above or below the price candles. When the dots are below, the trend is considered bullish. When they flip above, the trend has reversed. Its primary strength lies not in picking the start of a trend, but in systematically capturing the 'meat' of a move while protecting capital.
The Acceleration Factor (AF): The Engine of the Curve
The 'Parabolic' shape comes from the 'Acceleration Factor' (AF). By default, the AF starts at 0.02 and increases by 0.02 every time the price makes a new high (for longs) or low (for shorts), up to a maximum of 0.20.
What this means mathematically is that the indicator 'tightens' as the trend gains momentum. The faster the market moves in your direction, the faster the stop loss trails behind you. This allows traders to give a trade room early on, but lock in profits aggressively as the move goes parabolic.
Careful with the AF settings. Increasing the step to 0.03 or 0.04 makes the indicator extremely sensitive, often leading to premature exits in volatile markets.
Parabolic SAR Execution Checklist
Default Step: 0.02, Maximum AF: 0.20
Dots below = Bullish; Dots above = Bearish
Wait for Trend alignment on higher timeframes
Move stop loss manually to the dots every candle
Avoid using PSAR in sideways / chopping markets
Exit immediately on 'Dot Flip' regardless of profit
The Ultimate Trailing Stop Tool
Professional algorithmic traders rarely use PSAR as a standalone entry signal because it produces many 'whipsaws' in ranging markets. Instead, it is used as a mechanical trailing stop system for trades entered via other methods (like price action or EMA crosses).
Method: Once you are in a profitable trade, move your stop loss to the level of the newest PSAR dot every time a new candle opens. This removes emotional decision-making from the exit process. If the price touches a dot, the trend is statistically considered over, and you exit immediately.
Filtering PSAR with Higher Timeframe Trends
To avoid the 50/50 win rate of pure PSAR trading, use a higher timeframe trend filter. If the Daily chart is in a clear uptrend (price above 200 SMA), only take Parabolic SAR 'Buy' signals on the H1 or H4 charts.
Ignore all Parabolic SAR 'Sell' signals when the macro trend is bullish. Trading with the flow of institutional money significantly improves the reliability of the PSAR dots as a support/resistance floor.