Concept
Crab
Crab, also known as Deep Crab, is a Elliott & Harmonics concept. The Library holds 2 implementations, each one a working definition you can pull into Quant.
Top Crab indicators
2 total
What is a Crab?
The Crab is the most extended of the standard XABCD harmonic patterns, introduced by Scott Carney in 2000. B retraces 0.382 to 0.618 of the XA leg, C retraces 0.382 to 0.886 of AB, and D completes well beyond the X extreme at a 1.618 extension of XA, typically confluent with a 2.618 to 3.618 projection of BC. The Deep Crab variant permits a deeper B at 0.886 of XA while keeping the same 1.618 completion.
In Carney's treatment the terminal CD leg tends to arrive fast and stretched, so the 1.618 zone is watched for sharp snap-back reactions rather than gradual turns; the completion functions as a potential reversal zone with invalidation beyond it. As with every harmonic completion, the level is a place to evaluate a reversal with defined risk, not a ceiling or a floor.
How traders use it
- To fade climactic extensions: traders wait for price to reach the 1.618 XA projection, often after a near-vertical CD leg, and demand rejection behavior there before positioning against the move.
- To ladder targets: entries at D sit far from the pattern's origin, so profit-taking is commonly staged at successive retracements of the AD swing instead of a single objective.
- To separate candidates: scanners distinguish Crab from Butterfly setups by the B retracement (0.618 or less versus 0.786) together with the D projection (1.618 versus 1.27 of XA), and flag the Deep Crab when B sits near 0.886.
Crab vs neighboring harmonic patterns
Butterfly: Both complete beyond X, but the Butterfly finishes at 1.27 of XA with a 0.786 B, while the Crab runs to 1.618 with a shallower B; misjudging B invites treating a 1.27 touch as complete while a Crab is still extending.
Bat: Both use the 0.886 ratio, in different roles: it is the Bat's D completion inside XA, but the Deep Crab's B retracement before a 1.618 extension beyond X.
Related concepts · Harmonic patterns
Concept family
Elliott & Harmonics
33 concepts mapped · 17 in the Library
Crab FAQ
What is the difference between a Crab and a Deep Crab?
The B point. A standard Crab retraces 0.382 to 0.618 of XA at B, while the Deep Crab retraces about 0.886. Both complete in the same place, a 1.618 extension of XA beyond the X extreme, so the variant changes the internal shape and the BC projection rather than the completion zone itself.
Where does the Crab pattern complete?
At the 1.618 extension of the XA leg, beyond the X extreme, usually reinforced by a 2.618 to 3.618 projection of the BC leg. Because there is no structural level left beyond it, common practice sets invalidation with a buffer past the zone (a further extension or a volatility measure) and treats sustained trade through it as pattern failure.
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