Forex glossary
Crab Pattern
Crab is an XABCD harmonic formation with D beyond X at a 1.618 XA projection. In the regular version, B retraces 0.382–0.618 of XA, with additional projections defining the D zone. Its geometry does not guarantee reversal or a favorable trade outcome.
Illustrative example
How does it work in practice?
Assume a bullish candidate with X at 100 and A at 110. A 1.618 XA projection gives D at 93.82; that calculation uses the ten-unit XA leg rather than the CD leg.
A case to work through
Extension and variant
Hypothetically, X=50, A=60 and B=52.14; you are checking a classic Crab.
- D at 1.618 XA lies at 60−16.18=43.82.
- B retraces 78.6% XA, outside the classic Crab's usual 38.2–61.8% range.
What follows? Do not accept the classification merely because D fits.
Example boundary: Deep Crab has separate rules; a different B alone does not establish that variant.
A useful distinction
Crab Pattern / Butterfly Pattern
Crab uses the characteristic D=1.618 XA extension; an ideal Butterfly has D=1.27 XA and B=78.6%.
Check your understanding
Locate 1.618 XA and identify an incompatible B.
Show the answer and explanation
59.55
100−1.618×25=59.55.
Anchors, ratios and rules
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Related terms
Sources and documentation
- Harmonic Trader – Crab
The author's D=1.618 XA extension and separate Crab leg criteria.
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