Crab and Deep Crab Harmonic Patterns
Lesson 09 of 12. Differentiate extreme 161.8% XA completions and the role of B retracement.
1. Crab geometry
The Crab typically has B around 38.2–61.8% of XA and D around 161.8% extension of XA beyond X. Extreme D completion can occur in volatile trends.
2. Deep Crab geometry
The Deep Crab typically uses B near 88.6% of XA while retaining a D projection around 161.8% beyond X. The B depth is the main practical distinction.
3. BC projections
Depending on pattern specification, CD often extends about 224–361.8% of BC. Ratio catalogs vary, so declare one rule set before testing.
4. Worked XA example
With bullish X=100 and A=120, a 161.8% projection beyond X gives D=87.64, calculated as 120 minus 1.618 × 20. This is far below X and may require a wide invalidation distance.
5. Practical constraints
A distant PRZ can make a stop too expensive for a small account. Reduce position size or skip the trade; never enlarge risk simply to trade a textbook pattern.
6. Confirmation and targets
Look for measurable loss of downside momentum and a structure break after D. Target nearby resistance first, then compare additional AD retracements.
7. Pattern confusion
A deep B alone does not establish a Deep Crab. The full XA and BC projection geometry must be checked; otherwise label the structure unconfirmed.
8. Exercise
For ten hypothetical XA legs, compute 161.8% beyond-X levels and assess whether a proposed stop fits a fixed risk budget.
Knowledge check
- How does the D completion zone differ between a Crab and a Deep Crab?
- Which leg projections must overlap before calling a potential reversal zone credible?
- What is your invalidation rule if price extends beyond the projected zone?
Answer using the worked example above. Record your calculations and one reason the setup could fail before revealing any chart outcome.
Worked numerical example: Illustrative Crab extension
XA = 20; an illustrative 161.8% extension from A toward and beyond X places D at 120 − (1.618 × 20) = 87.64. Crab and Deep Crab differ in B placement and other internal ratio requirements; do not label them interchangeably.
Practice and answer
Show worked answer
A 60% B retracement is a numerical practice value, not proof of a valid Crab or Deep Crab. Compare the actual B, C and D relationships with the selected pattern specification and discard the candidate if a mandatory leg is outside tolerance.
Independent worked analysis: Deep extensions make execution especially sensitive
Hypothetical worked example: Take a 100-pip XA leg. A 161.8% extension represents 161.8 pips of projected movement, not a 61.8-pip retracement. The resulting D level may lie far beyond the original X pivot.
Calculation and decision exercise: Sketch both a Crab and a Deep Crab using the ratio rules your course defines. Label which constraints belong to B and which belong to D rather than mixing their names.
What this example cannot establish: The deeper the completion, the larger the potential stop and volatility exposure. A narrow drawn zone is not evidence of narrow execution risk.
Evidence checklist for this specific lesson
- Write down the precise inputs used in the deep extensions make execution especially sensitive example, including their units and observation dates.
- Distinguish what can be computed directly from what must be inferred about future prices or policy.
- Test the opposite interpretation using a clearly stated alternative assumption, not a revised chart drawn after the outcome.
- Document transaction costs and the maximum hypothetical loss before treating any market view as an executable strategy.
Applied analysis: testing the lesson in context
The following exercise develops the specific decisions involved in crab and deep crab harmonic patterns. It is a hypothetical training workflow, not a prediction or an instruction to place a live trade. Keep the market, time zone, instrument, observation window and data source fixed before evaluating the idea. Separate what the chart shows from the interpretation assigned to it; two analysts can label the same sequence differently without either label being a verified market mechanism.
Case step 1: 1. Crab geometry
Start with the lesson's 1. crab geometry component. Source observation: The Crab typically has B around 38.2–61.8% of XA and D around 161.8% extension of XA beyond X. Extreme D completion can occur in volatile trends. Record the exact candle or pivot at which this information first became available. If confirmation depends on a later close, mark that later close as the earliest legitimate decision point. A visually compelling retrospective drawing is not sufficient evidence that the setup was identifiable in real time.
Now construct a counterexample for 1. crab geometry: imagine the price initially behaves as the lesson suggests but then fails to follow through. Write the invalidation condition as an observable price or time event, not as a vague change in confidence. Compare two annotated screenshots, one before the proposed confirmation and one after it. Explain what genuinely changed in the available evidence. For a trading-system study, record spread, slippage, position size, and whether the proposed stop could have been filled at the assumed price.
Case step 2: 2. Deep Crab geometry
Start with the lesson's 2. deep crab geometry component. Source observation: The Deep Crab typically uses B near 88.6% of XA while retaining a D projection around 161.8% beyond X. The B depth is the main practical distinction. Record the exact candle or pivot at which this information first became available. If confirmation depends on a later close, mark that later close as the earliest legitimate decision point. A visually compelling retrospective drawing is not sufficient evidence that the setup was identifiable in real time.
Now construct a counterexample for 2. deep crab geometry: imagine the price initially behaves as the lesson suggests but then fails to follow through. Write the invalidation condition as an observable price or time event, not as a vague change in confidence. Compare two annotated screenshots, one before the proposed confirmation and one after it. Explain what genuinely changed in the available evidence. For a trading-system study, record spread, slippage, position size, and whether the proposed stop could have been filled at the assumed price.
Case step 3: 3. BC projections
Start with the lesson's 3. bc projections component. Source observation: Depending on pattern specification, CD often extends about 224–361.8% of BC. Ratio catalogs vary, so declare one rule set before testing. Record the exact candle or pivot at which this information first became available. If confirmation depends on a later close, mark that later close as the earliest legitimate decision point. A visually compelling retrospective drawing is not sufficient evidence that the setup was identifiable in real time.
Now construct a counterexample for 3. bc projections: imagine the price initially behaves as the lesson suggests but then fails to follow through. Write the invalidation condition as an observable price or time event, not as a vague change in confidence. Compare two annotated screenshots, one before the proposed confirmation and one after it. Explain what genuinely changed in the available evidence. For a trading-system study, record spread, slippage, position size, and whether the proposed stop could have been filled at the assumed price.
Evidence record and independent assessment
Create a small research log specifically labelled “Crab and Deep Crab Harmonic Patterns”. For each candidate observation, store its date, instrument, session, timeframe, setup definition, entry eligibility, invalidation level, expected costs, and actual subsequent path. Include candidates that never triggered, rather than selecting only attractive examples. Compare at least two market regimes and note whether the interpretation changes when a nearby swing anchor or session boundary is chosen. If it does, classify the result as sensitive to analyst discretion rather than robust evidence.
Finally, write a three-part conclusion about crab and deep crab harmonic patterns: (1) which elements can be verified directly from historical prices, (2) which elements are hypotheses about participants or future behavior, and (3) what observation would cause you to reject the hypothesis. The exercise is complete only when a second reader could reproduce your markings using the written rules. Do not infer a profitable edge from a single worked example; that requires a separately designed, cost-aware and out-of-sample evaluation.