Concept
ABCD
ABCD, also known as extended ABCD, is a Elliott & Harmonics concept. The Library holds 3 implementations, each one a working definition you can pull into Quant.
Top ABCD indicators
3 total
What is an ABCD?
The ABCD, often written AB=CD, is the simplest harmonic pattern: two price legs of matching length separated by a correction. Price travels from A to B, corrects to C (commonly 0.618 to 0.786 of AB), then travels from C to D until CD equals AB in price distance. In the common reading the completion also lands near a 1.27 to 1.618 extension of the BC leg, and the extended ABCD variant substitutes CD equal to 1.27 or 1.618 times AB when exact equality fails.
The measurement dates back to H.M. Gartley's era and works as the building block of the larger XABCD patterns: an AB=CD finishing at the D point is part of what defines a Gartley. Some practitioners also weigh time symmetry, preferring patterns where AB and CD consume a comparable number of bars. Equality is a zone to watch for reaction, not a wall; trending markets push through it routinely.
How traders use it
- To project a completion in advance: once A, B, and C are in place, D is measurable (the length of AB projected from C), so traders set alerts or resting orders around the level and evaluate the reaction when price arrives.
- As a defined-risk reversal entry: at D, traders look for confirmation, place stops beyond the completion (or beyond the 1.27 extension when tracking the extended variant), and stage targets at retracements of the CD leg.
- As a component inside larger structures: XABCD detectors typically require an AB=CD or extended ABCD to terminate at the same place as the pattern's D point before flagging a Gartley, Bat, or Butterfly.
ABCD vs related patterns
Three Drives: Three Drives chains three symmetric pushes to successive extremes with corrective pullbacks between them; the ABCD is a single two-leg symmetry, and a Three Drives often contains overlapping ABCD measurements.
Gartley: The Gartley is a five-point pattern anchored at X whose D typically combines a 0.786 XA retracement with an AB=CD completion; the ABCD alone carries no X anchor and no retracement requirement against a prior leg.
Related concepts · Harmonic patterns
Concept family
Elliott & Harmonics
33 concepts mapped · 17 in the Library
ABCD FAQ
What is the difference between ABCD and extended ABCD?
In the classic AB=CD, the CD leg matches the AB leg in price distance. In the extended variant, CD runs to a fixed multiple of AB, most commonly 1.27 or 1.618. Traders track both projections because a market that ignores exact equality often reacts near the next harmonic multiple instead; neither level is guaranteed to hold.
Does the ABCD pattern work in both directions?
Yes. A bullish ABCD declines from A to B, corrects up to C, and declines again into D, where buyers watch for a turn; the bearish version is the mirror image. The measurements are identical either way: C near 0.618 to 0.786 of AB, and CD matching AB or extending to 1.27 to 1.618 of it.
Build ABCD your way.
Quant writes, tests, and refines it with you — then it runs on LuxAlgo charting or ports to TradingView.