# Stop-and-reverse A Risk, Sizing & Exits concept (Exit taxonomy) in the LuxAlgo Library, with 1 indicator implementation. ## What is Stop-and-reverse? Stop-and-reverse (SAR) is an exit style in which the stop is also the next entry: when price hits the level that invalidates a long, the system closes the long and opens a short in the same act, and vice versa. A pure stop-and-reverse system is therefore always in the market, alternating long and short with no flat state. The idea is baked into several classic tools: Wilder's Parabolic SAR is named for it, moving average crossovers reverse at every cross by construction, and flip-style trailing overlays such as Supertrend, one branch of the [trailing method taxonomy](https://www.luxalgo.com/library/concept/trailing-method-taxonomy/), mark a reversal point each time price crosses the trailing band. The lineage runs through early mechanical trend following, where systems that flipped position on the opposite signal were a staple of mid-twentieth-century channel and breakout research. The acronym spread through J. Welles Wilder's New Concepts in Technical Trading Systems (1978), whose Parabolic Time/Price system trails a level that accelerates toward price and reverses the position when touched. The appeal was mechanical purity: one rule set defines both sides of the market, with no separate exit logic to tune. Many chartists have since gone the other way, plotting the parabolic dots purely as a trailing exit and never taking the reverse trade. The always-in property is the whole trade-off. In persistently trending markets it means the system cannot miss the turn: the losing side closes exactly when the winning side begins. In choppy regimes it roughly doubles the cost of every whipsaw, since each false flip books a loss and immediately exposes the account in the new, equally wrong direction. That is why many modern implementations demote the reversal side to an alert or exit-only signal, gating actual reversals behind a regime filter. Reversal mechanics also reshape risk arithmetic. A flip closes one position and opens the opposite one, so the executed size at the reversal is double the position size, which matters for slippage in thin markets and for how the flip is expressed in [order constructs](https://www.luxalgo.com/library/concept/order-constructs/). The flip distance is the risk on every leg, so disciplined implementations define it in [R-multiple terms](https://www.luxalgo.com/library/concept/r-multiple-framework/) and cap runaway whipsaw sequences with [loss-control rules](https://www.luxalgo.com/library/concept/loss-control-rules/) such as daily stop-out limits. ## How to identify stop-and-reverse behavior on a chart Stop-and-reverse is a property of a system or overlay rather than a price pattern, but it is easy to spot once plotted. 1. Apply a flip-style overlay (Parabolic SAR dots, a Supertrend-like band, or crossover markers): it sits below price when bullish and above price when bearish. 2. Locate the flips, bars where the marker jumps to the other side of price; each flip is simultaneously an exit and an opposite entry. 3. Confirm there are no flat periods: each position ends exactly where the next begins, alternating long and short without gaps. 4. Count flips inside the most recent congestion zone; tight alternation there is the signature whipsaw cost of always-in logic in ranging tape. ## How traders use it - As the skeleton of always-in trend systems: channel-breakout and crossover strategies that reverse on the opposite signal, accepting whipsaw costs in exchange for never sitting out a major trend leg. - As exit-plus-alert logic: the reversal level closes the position, while the would-be reverse entry is downgraded to an alert that requires separate confirmation, such as a higher-timeframe trend filter, before real size goes on. - As a benchmark in system design: running a strategy's exit logic, a [structure stop](https://www.luxalgo.com/library/concept/structure-stop/) trail for instance, against a simple stop-and-reverse variant on the same entries shows whether the added exit complexity actually earns its keep versus always-in behavior. - As a sizing discipline: the flip distance defines each leg's risk, so position size is back-solved with [fixed fractional](https://www.luxalgo.com/library/concept/fixed-fractional/) rules rather than chosen first, keeping every alternation's loss a constant fraction of equity. ## Stop-and-reverse vs related exit logic - **Trailing Method Taxonomy** (https://www.luxalgo.com/library/concept/trailing-method-taxonomy/): The taxonomy catalogues the ways a stop can follow price: swing-based, volatility-based, parabolic, profit-locking. Stop-and-reverse is the aggressive end of that family: where other trailing methods exit to flat when hit, the SAR trail doubles as the next entry. - **Volatility Stop** (https://www.luxalgo.com/library/concept/volatility-stop/): A volatility stop trails at an ATR multiple, the chandelier variant hanging it from the highest high of the move, and exits to flat when touched. It becomes stop-and-reverse the moment the rules take the opposite trade at the touch; the distance logic is identical, the difference is whether a flat state exists. ## FAQ ### Is a stop-and-reverse system better than exiting to flat? Neither dominates. Always-in systems catch every major reversal by construction but pay for every whipsaw twice, so their relative performance depends on how often the market trends versus chops. Exit-to-flat systems skip the second loss in chop but can sit out the start of real trends. Testing both exit styles on the same entry signals is the only honest way to decide for a given market. ### Does SAR mean Parabolic SAR? Not necessarily. SAR abbreviates stop-and-reverse, the general concept of a stop that simultaneously opens the opposite position. Wilder used the acronym for a specific indicator whose trailing dots accelerate toward price, and that indicator's popularity made the abbreviation ambiguous. Context usually resolves it: a 'SAR system' means always-in reversal logic, while 'the SAR indicator' almost always means the parabolic one. ### Who invented the stop-and-reverse concept? No single originator is documented: any system that always acts on the opposite signal is implicitly stop-and-reverse, and such systems pervade early mechanical trend-following research. The acronym is most closely associated with J. Welles Wilder, whose 1978 book introduced the Parabolic Time/Price system built around reversing at the trailing level. ### How do you size a stop-and-reverse trade? From the flip distance. The gap between entry and the reversal level is the risk per unit, so size is chosen so that distance times size equals the risk budget, the stop-first arithmetic used across [sizing bases](https://www.luxalgo.com/library/concept/sizing-bases/). Remember the reversal order executes double size, one unit to close and one to open, raising slippage exposure in thin conditions. ### Can stop-and-reverse be combined with pyramiding or scaling out? Yes, with care. Some always-in systems add units as the trend extends, in the spirit of [pyramiding](https://www.luxalgo.com/library/concept/pyramiding/), reversing only the base unit at the flip; others cut exposure into strength via [scaling out](https://www.luxalgo.com/library/concept/scaling-out/) so the reversal starts small. Both hybrids trade always-in purity for smoother equity behavior. ### Why do stop-and-reverse systems struggle in ranges? Because every false flip is charged twice: the old position exits at a loss and the new one opens facing the same chop. A range that costs an exit-to-flat system one stop-out can charge an always-in system a sequence of alternating losses, so practical implementations often add a regime filter or demote reversals to alerts in congestion. ## Implementations in the Library - Stop-and-reverse (LuxAlgo): https://www.luxalgo.com/library/indicator/stop-and-reverse/ ## Related concepts - Profit Target Taxonomy: https://www.luxalgo.com/library/concept/profit-target-taxonomy/ - Scaling Out: https://www.luxalgo.com/library/concept/scaling-out/ - Non-price Exits: https://www.luxalgo.com/library/concept/non-price-exits/ --- Source: https://www.luxalgo.com/library/concept/stop-and-reverse/ (LuxAlgo Library, the encyclopedia of trading & technical analysis). Free to use with attribution: https://www.luxalgo.com/library/license/