# Bat Also known as: Alt Bat. A Elliott & Harmonics concept (Harmonic patterns) in the LuxAlgo Library, with 1 indicator implementation. ## What is a Bat? The Bat is an XABCD harmonic retracement pattern defined by Scott Carney in 2001, distinguished by a shallow midpoint and a deep completion: B retraces less than 0.618 of the XA leg (0.382 to 0.50 in the standard definition), C retraces 0.382 to 0.886 of AB, and D completes at the 0.886 retracement of XA, typically confluent with a 1.618 to 2.618 extension of BC. Like the [Gartley](https://www.luxalgo.com/library/concept/gartley/), the Bat finishes inside the XA leg, so the X extreme caps the structure. Carney later added the Alt Bat, which keeps an even shallower B (0.382 of XA or less) but completes beyond X at a 1.13 extension of XA. In both versions the D point is treated as a [potential reversal zone](https://www.luxalgo.com/library/concept/potential-reversal-zone/) where the move against XA is watched for a turn; decisive trade through the invalidation level voids the pattern rather than postponing it. The completion zone is a confluence construction, not a single line. The primary coordinate is the 0.886 retracement of XA; the BC extension between 1.618 and 2.618 should land in the same neighborhood, and an [ABCD](https://www.luxalgo.com/library/concept/abcd/) projection of the AB leg from C commonly tightens the zone further. Carney's Harmonic Trading volumes, which formalized the pattern, emphasize that the stack of ratios is the point: a D where several independent measurements agree is the zone worth watching, while a lone 0.886 touch with nothing else aligning is a number, not a pattern. The Bat's practical appeal inside the [harmonic](https://www.luxalgo.com/library/concept/harmonic-patterns/) family is its risk geometry: because 0.886 sits close under X, the structural stop is near the entry, so the reward-to-risk of a working reversal is among the family's best. Detection tools, from LuxAlgo's Harmonic Pattern Detection to reees' detection-and-backtesting study, automate the ratio measurement and let the completion statistics be checked per instrument rather than taken on faith, which matters because published success rates for harmonic patterns are vendor-quoted and unaudited. ## How to identify a Bat pattern Four legs, three ratio tests, one confluence zone: the measurements are the pattern. 1. Anchor the XA leg: a clear directional impulse whose retracement the pattern will structure. 2. Test the B point first: a retracement of 0.382 to 0.50 of XA, and never past 0.618; this measurement is what separates Bat candidates from Gartleys. 3. Check C: a retracement of 0.382 to 0.886 of the AB swing, keeping the midsection inside the structure. 4. Project D: the 0.886 retracement of XA, cross-checked against a 1.618 to 2.618 extension of BC landing in the same zone. 5. Trade the reaction, not the arrival: wait for rejection behavior in the completion zone, enter back in the XA direction, and void the pattern on decisive trade through X. ## How it's calculated A five-point XABCD retracement pattern whose completion point D is set by a 0.886 retracement of the opening XA leg. ``` 1. Mark five alternating swing pivots X, A, B, C, D forming legs XA, AB, BC, CD (XA an advance for the bullish pattern, a decline for the bearish one). 2. Require the mid-point B: abs(B - A) / abs(A - X) between 0.382 and 0.50. 3. Require the pivot C: abs(C - B) / abs(B - A) between 0.382 and 0.886. 4. Project D as a BC extension: abs(D - C) / abs(C - B) between 1.618 and 2.618. 5. Require the defining completion: abs(D - A) / abs(A - X) = 0.886, so D holds inside the XA leg, beyond B but short of X. 6. The pattern completes when price reaches D, where the 0.886 XA level and the BC extension window overlap. X: price of the pattern's starting pivot A: price of the pivot ending the opening leg XA B: price of the pivot ending leg AB C: price of the pivot ending leg BC D: completion price of the pattern XA, AB, BC, CD: the four legs, named by their endpoint pivots abs(): absolute value of the price difference 0.382 to 0.50: retracement window for B relative to XA 0.382 to 0.886: retracement window for C relative to AB 1.618 to 2.618: extension window for D relative to BC 0.886: defining XA retracement at D, with 0.886 = sqrt(0.786) ``` Ratios follow Scott Carney's published definition; B must stay below 0.618, since at 0.618 the structure grades as a Gartley instead. Alt Bat variant: B at 0.382 or less of XA, completion at a 1.13 extension of XA (slightly beyond X), and a BC extension window of 2.0 to 3.618. Automated detection typically allows a small tolerance around each ratio. ## How traders use it - As a deep-pullback entry: once B holds at or under 0.50 of XA, traders project the 0.886 level and wait for price to trade into it and show rejection before entering back in the XA direction. - For tight, structural risk: because D at 0.886 sits close to X, stops beyond the X extreme are comparatively near the entry, with targets commonly staged at retracements of the AD swing. - As a classification gate: pattern scanners measure the B retracement first, since it is the main separator between Bat and Gartley candidates, and only then project the matching D. - In confluence with the broader [ratio toolkit](https://www.luxalgo.com/library/concept/harmonic-and-fib-ratio-set/): completion zones that also line up with structural levels, prior swing points or session extremes, outrank pure ratio zones floating in space. - With backtested expectations: detection-and-backtesting tools measure how often completions in a given market actually reverse and how far, replacing the folklore numbers with per-instrument evidence before risk is committed. ## Bat vs neighboring harmonic patterns - **Gartley** (https://www.luxalgo.com/library/concept/gartley/): Both complete inside XA, but the ratios differ at both defining points: a 0.618 B with a 0.786 D makes a Gartley, while a 0.50-or-less B with a 0.886 D makes a Bat. - **Crab** (https://www.luxalgo.com/library/concept/crab/): The Crab shares the shallow-to-moderate B but completes far beyond X at a 1.618 extension of XA, making it an extension pattern; the standard Bat completes inside XA at 0.886. - **Butterfly** (https://www.luxalgo.com/library/concept/butterfly/): The Butterfly is the Bat's mirror in profile: a deep 0.786 B point with a completion beyond X, typically at a 1.27 extension of XA. Deep midpoint with external completion versus shallow midpoint with deep internal completion; the B measurement separates them immediately. ## FAQ ### What is the difference between a Bat and a Gartley pattern? The B and D ratios. A Gartley retraces about 0.618 of XA at B and completes at 0.786 of XA; a Bat retraces 0.50 or less at B and completes deeper, at 0.886. Both are XABCD retracement patterns finishing inside the XA leg, so in practice the B-point measurement is the deciding test. ### What is an Alt Bat pattern? A later Carney variant with a stricter B point, 0.382 of XA or less, that completes beyond the X extreme at a 1.13 extension of XA instead of the 0.886 retracement. It describes the case where a standard Bat's zone gets run before price turns, so invalidation and targets key off the 1.13 level rather than X itself. ### What are the exact Bat ratios? B at 0.382 to 0.50 of XA (and strictly under 0.618), C at 0.382 to 0.886 of AB, and D at the 0.886 retracement of XA, confluent with a BC extension between 1.618 and 2.618. The Alt Bat tightens B to 0.382 or less and moves D to a 1.13 extension of XA. Scanners tolerate small deviations around each number; the structure of shallow B and deep D is what defines the species. ### Where do stops and targets go on a Bat trade? The structural stop sits just beyond X, which the 0.886 completion keeps close to the entry, one of the pattern's main attractions. Targets are conventionally staged at retracements of the AD swing, 0.382 first and 0.618 beyond it, with management tightening as each stage fills. For the Alt Bat the same logic keys off the 1.13 extension instead of X itself. ### How reliable is the Bat pattern? Honest answer: the published success rates circulating in harmonic literature are vendor-quoted and unaudited, and completion behavior varies by market and era. The pattern's defensible core is its risk geometry, a precisely defined zone with a nearby structural invalidation, which makes losing attempts cheap relative to working ones. Backtesting tools that measure completions per instrument give a better basis than any borrowed statistic. ### Do Bats work on all timeframes? The ratio geometry is scale-free, so detectors find Bats from minute charts to weeklies. What changes is noise: on low timeframes the swings defining X, A, B and C are frequently microstructure rather than participation, so completion zones carry less meaning, while higher-timeframe patterns form from swings enough traders actually traded. The standard compromise identifies the pattern on a higher frame and times the D-zone reaction on a lower one. ## Implementations in the Library - Harmonic Pattern Detection (LuxAlgo): https://www.luxalgo.com/library/indicator/harmonic-pattern-detection/ ## Related concepts - Harmonic Patterns: https://www.luxalgo.com/library/concept/harmonic-patterns/ - ABCD: https://www.luxalgo.com/library/concept/abcd/ - Three Drives: https://www.luxalgo.com/library/concept/three-drives/ - Gartley: https://www.luxalgo.com/library/concept/gartley/ - Butterfly: https://www.luxalgo.com/library/concept/butterfly/ - Shark: https://www.luxalgo.com/library/concept/shark/ - Cypher: https://www.luxalgo.com/library/concept/cypher/ - 5-0: https://www.luxalgo.com/library/concept/5-0/ - Anti-patterns: https://www.luxalgo.com/library/concept/anti-patterns/ - Exotic Harmonics: https://www.luxalgo.com/library/concept/exotic-harmonics/ --- Source: https://www.luxalgo.com/library/concept/bat/ (LuxAlgo Library, the encyclopedia of trading & technical analysis). Free to use with attribution: https://www.luxalgo.com/library/license/