Fibonacci Extension

The five canonical extension ratios (127.2/141.4/161.8/200/261.8%) of the most recent swing leg, projected in the direction of the move — the targets a continuation would reach.

Quick reference

Item	Value
Family	Fibonacci
Input type	Candle (uses high, low)
Output type	FibExtensionOutput (5 prices)
Output range	beyond the leg end, in the move direction
Default parameters	none (swing threshold 5%, baked)
Warmup period	2 (two confirmed pivots)
Interpretation	Continuation price targets

Formula

last two confirmed pivots define a leg start -> end:
  level(e) = start + e * (end - start)
for e in {1.272, 1.414, 1.618, 2.0, 2.618}

Each level is a multiple of the leg measured from its origin, so every ratio projects past end in the direction of the move. See crates/wickra-core/src/indicators/fib_extension.rs.

Parameters

None. The swing threshold 0.05 is a baked-in family constant (pattern_swing.rs); the five ratios are fixed. FibExtension::new is infallible.

Inputs / Outputs

const _: fn(&mut wickra::FibExtension, wickra::Candle) -> Option<wickra::FibExtensionOutput> =
    <wickra::FibExtension as wickra::Indicator>::update;

• Python. update((o,h,l,c,v,ts)) → (level_1272, level_1414, level_1618, level_2000, level_2618) or None; batch(high, low) → (n, 5) ndarray (NaN warmup rows).
• Node. update(high, low) → { level1272, level1414, level1618, level2000, level2618 } or null; batch(high, low) → flat number[] length n*5.
• WASM. update(high, low) → object (same camelCase keys) or null.

Warmup

warmup_period() == 2. Two confirmed pivots define the leg; before that update returns None. Pinned by tests accessors_and_metadata and no_output_before_two_pivots.

Edge cases

• Extension levels of a confirmed down leg are exact, including the 200% level landing on 0 for a 200→100 leg (test extension_levels_of_a_down_leg).
• reset clears all state (test reset_clears_state).
• Streaming equals batch (test batch_equals_streaming).

Examples

Rust

use wickra::{Candle, FibExtension, Indicator};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Leg 200 (high) -> 100 (low); extensions project the drop further down.
    let bars = [
        (199.8, 200.0, 199.8, 199.8),
        (100.0, 198.0, 100.0, 100.0),
        (101.0, 110.0, 101.0, 101.0),
    ];
    let mut fib = FibExtension::new();
    let mut last = None;
    for (ts, (o, h, l, c)) in bars.iter().enumerate() {
        last = fib.update(Candle::new(*o, *h, *l, *c, 1.0, ts as i64)?);
    }
    let v = last.unwrap();
    println!("{} {} {}", v.level_1272, v.level_1618, v.level_2000); // 72.8 38.2 0
    Ok(())
}

Python

import wickra as ta

bars = [
    (199.8, 200.0, 199.8, 199.8, 1.0, 0),
    (100.0, 198.0, 100.0, 100.0, 1.0, 1),
    (101.0, 110.0, 101.0, 101.0, 1.0, 2),
]
fib = ta.FibExtension()
print([fib.update(b) for b in bars][-1])
# (72.8, 58.6, 38.2, 0.0, -61.8)

Node

const wickra = require('wickra');
const fib = new wickra.FibExtension();
let last = null;
for (const [h, l] of [[200.0, 199.8], [198.0, 100.0], [110.0, 101.0]]) {
  last = fib.update(h, l);
}
console.log(last.level1272, last.level1618); // 72.8 38.2

Streaming

fib = ta.FibExtension()
for o, h, l, c, v, ts in candle_feed:
    ext = fib.update((o, h, l, c, v, ts))
    if ext is not None:
        target = ext[2]  # 161.8% — a common take-profit

Interpretation

1. Where might it reach. Once a leg completes and price breaks past it, extensions mark plausible continuation targets; 161.8% is the most cited.
2. Mirror of retracement. FibRetracement maps the 0-100% pullback of the same leg; extensions map the >100% continuation.

Common pitfalls

• Two-point, not measured-move. This projects a single leg. For an A-B-C measured move use FibProjection.
• Direction follows the leg. A down leg extends downward (levels can fall below zero in synthetic data); always read levels relative to the leg sign.

References

• Fischer, R. Fibonacci Applications and Strategies for Traders (1993).

See also

• FibRetracement, FibProjection, FibConfluence.
• Indicators-Overview — full taxonomy.