Indicator: What Is Parabolic SAR? Trailing Trend Reversals

Parabolic SAR (Stop And Reverse) plots a series of dots directly on the price chart, above or below the candles, to show the current trend direction and a trailing stop level that moves closer to price as the trend matures. Another J. Welles Wilder design (like RSI, ATR, and ADX), its name describes its original use literally: the dot is where you stop the current trade and reverse into the opposite one — a system that is always in the market, long or short.

How to Read the Dots

• Dots below price — the market is in an uptrend. The dots trail upward underneath price and can be used as a trailing stop-loss level.
• Dots above price — the market is in a downtrend. The dots trail downward above price, again usable as a trailing stop.
• A flip — when price crosses through the dots, SAR flips to the other side, signaling a potential trend reversal.

The "parabolic" part is the accelerating curve the dots trace: each new dot starts far from price, then closes in faster and faster the longer the trend runs and the further it extends. The practical effect is deliberate — a young trend gets room to breathe, while an old, extended trend gets a progressively tighter leash, locking in more of the open profit the longer the move lasts.

The Settings

Platforms expose two parameters: the Step (Acceleration Factor, default 0.02) and the Maximum (default 0.20). The step controls how quickly the dots accelerate toward price — each new extreme in the trend speeds them up by this amount — and the maximum caps that speed. A larger step (e.g. 0.04) hugs price tighter: earlier exits, more whipsaws. A smaller one (e.g. 0.01) trails looser: fewer false flips, more open profit surrendered at the real turn. The defaults are Wilder's own and remain what most traders use.

Entry Conditions

• BUY — the dots flip from above price to below price, suggesting the downtrend has ended and an uptrend is starting.
• SELL — the dots flip from below price to above price, suggesting the uptrend has ended and a downtrend is starting.

Because each dot also marks a trailing stop level, many traders use Parabolic SAR less for the initial entry and more to decide when to exit a trade that's already open — and this exit role is where the indicator genuinely shines.

SAR as a Trailing-Stop Discipline

Managing a winning trade is one of the hardest practical problems in trading — exit too early and the big wins that pay for the losses never happen; hold too long and open profit evaporates. SAR turns that judgment call into a mechanical routine:

1. Enter a trade using whatever setup you actually trade (a MACD crossover, a bounce at support, a breakout).
2. Each new candle, move the Stop Loss to the current SAR dot — never backwards, only tighter.
3. The trade ends when price hits the trailed stop; no discretion required.

This pairs naturally with the volatility-based initial stop from the ATR lesson: ATR sizes the stop at entry, SAR takes over management once the trade moves in your favor.

A Word of Caution

Parabolic SAR is built for trending markets — and is arguably the worst-behaved common indicator in ranging ones. Because it's always positioned on one side of price and always flips when crossed, a sideways market forces it to flip back and forth constantly, generating a steady drip of false signals and small losses (the "whipsaw" problem). There is no neutral state; SAR always claims a trend exists, even when none does.

It works best combined with a trend-strength filter, and the classic pairing is with ADX — its sibling from the same creator: only honor SAR flips when ADX is above ~25, and ignore them (or stand aside entirely) when ADX says the market is choppy. A simpler filter is a long-period Moving Average: only take bullish SAR flips above it, bearish flips below it. And note that SAR dots make no distinction between a trend pausing and a trend ending — see Trend vs Range for the structural read that should come first.

Download the Indicator

This custom indicator plots Parabolic SAR dots on the chart, with automatic alerts whenever the dots flip sides. It's available for both MetaTrader 4 and MetaTrader 5 below.

How to Install — MetaTrader 4

1. Download the parabolic-sar-alert.mq4 file below.
2. Open MetaTrader 4 → click File → Open Data Folder.
3. Place the file in the MQL4/Indicators folder.
4. Restart MetaTrader 4, then drag the indicator from the Navigator window onto the chart.

How to Install — MetaTrader 5

1. Download the parabolic-sar-alert.mq5 file below.
2. Open MetaTrader 5 → click File → Open Data Folder.
3. Place the file in the MQL5/Indicators folder.
4. Restart MetaTrader 5, then drag the indicator from the Navigator window onto the chart.

Both files are source code — open and review the full code before using it, for your own safety.