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AB=CD pattern

AB=CD is the simplest harmonic structure: a move (AB), a retracement (BC), and a second move (CD) equal to the first. When CD equals AB in price, and ideally in time, D is a potential reversal or pause point.

What it's for
  • Spot a leg that repeats the length (and ideally the duration) of the previous one.
  • Locate a potential reversal or pause point at D.
Plus and Pro toolTry it in Analyze
Points
4: A, B, C, D
Plan
Plus and Pro
Checked
BC/AB 0.382–0.886, CD/BC 1.13–2.618, CD/AB
Ideal
CD = AB (±5%)

Structure and ratios

Oyticker labels the pattern AB=CD when the ratios are valid and CD is within 5% of AB, and ABCD when the ratios are valid but the legs are unequal. The two pills on the dashed lines show the BC retracement of AB and the CD extension of BC. The two are linked: with a 0.618 retracement, an equal CD leg is 1.618 times BC.

Bullish AB=CD with BC 0.618 and CD 1.618 of BC, equal legs in price and time
A bullish AB=CD: BC retraces 0.618 of AB, CD extends 1.618 of BC, and CD equals AB in price (CD/AB = 1.00) and in time (12 bars each). Price turns up from D.

How to draw it

  1. Choose Patterns → AB=CD and click A, B, C, D on alternating swing points.
  2. Compare the time of the two legs with the date range tool: equal durations strengthen the pattern.

To anticipate D before it forms, draw a trend-based Fibonacci extension on A, B and C: level 1.0 is exactly where CD = AB.

Limits

Legs are often unequal in strong trends (CD = 1.272 or 1.618 × AB is common). D is a place to look for a reaction, not a signal by itself.

Charts in this guide use simulated prices generated for illustration; levels and outcomes shown are examples, not observations of a real market. Educational content only, not investment advice.

Related guides

Harmonic patterns (XABCD)PlusHow to draw an XABCD harmonic pattern, the exact Fibonacci ratios of the Gartley, Bat, Butterfly, Crab, Deep Crab and Cypher, and how Oyticker recognizes them.Trend-based Fibonacci extensionPlusHow the trend-based Fibonacci extension projects the A-B swing from the end of the pullback C, and how to use the 1.0, 1.272 and 1.618 targets.Elliott correction (A-B-C)PlusHow to label an Elliott A-B-C correction, recognize zigzags and flats, and use wave relationships to anticipate the end of wave C.