Parabolic SAR (PSAR)

The Parabolic SAR (Stop and Reverse), developed by J. Welles Wilder, is a trend-following indicator that plots a series of dots above or below the price chart to indicate the current trend direction and suggest stop-loss placement. When the dots appear below the candles, the trend is bullish and traders should hold long positions; when the dots appear above the candles, the trend is bearish and short positions are favored. The "SAR" label stands for Stop and Reverse — the principle being that when price crosses through the SAR level, you stop your current position and reverse into the opposite direction, following the new trend.

The SAR dots move progressively closer to the price as a trend continues, accelerating toward the current price at a rate determined by the "acceleration factor" (typically starting at 0.02 and increasing by 0.02 each period up to a maximum of 0.20). This acceleration reflects the real-world tendency of trends to gather momentum over time, placing the stop loss closer to the price as the move extends — protecting accumulated profits. A new trend begins when price crosses through the current SAR dot, at which point the dots flip to the other side and the acceleration factor resets.

For crypto algorithmic traders, the Parabolic SAR is an exceptionally practical tool because it provides not just entry and exit signals but also a built-in trailing stop mechanism that is mathematically defined and requires no subjective judgment. Bots can use the SAR flip as an entry trigger and continuously update the stop-loss level to the current SAR dot as the trade progresses. This ensures that profits are protected in long-running trends while allowing the trade to breathe in the early stages. In fast-moving crypto markets, the adjustable acceleration factor allows bots to be tuned for aggressive trailing in volatile conditions or more conservative behavior in steady trends.