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Engulfing

Patterns candlestick reversal momentum

A two-candle reversal pattern in which a large candle body completely engulfs the entire range (or at minimum the body) of the preceding candle. It represents a decisive shift in control from one side to the other.

Visual Example

Bullish Engulfing: small red candle followed by a large green candle whose body fully engulfs the prior candle's range. Shaded region and annotation highlight the complete coverage of the prior high-low.

Synthetic ideal per library logic. Generated 2026-06-25 IST via docs/generate_all_previews.py (reproducible; maps to core Next<T> implementation).

Description

The Engulfing pattern is one of the most visually compelling and statistically frequent reversal signals. The second candle opens at or beyond the prior close and then closes decisively beyond the prior open, "swallowing" the previous period's action.

It is especially potent when it occurs at a Market Structure support/resistance level or after a prolonged trend. Quant developers use it both as a direct signal generator and as a high-signal binary feature in ML pipelines (often gated by volume expansion or regime filters).

Formula / Specification

Recognition Rules (exact implementation in QuantWave / TA-Lib CDLENGULFING):

  1. Prior bar: close < open (red body) for bullish engulfing (symmetric for bearish).
  2. Current bar: close > open (green body).
  3. Current open \le prior close.
  4. Current close \ge prior open.
  5. The engulfing body covers the prior body (TA-Lib reference focuses on body containment; full range variants exist in literature).
  6. Pattern completes on the second bar; stateless beyond the two-bar window in the wrapper.

Parameters

Parameter Default Description
(none) — Pattern recognition only; no tunable parameters. Some higher-level consumers accept an optional volume-confirmation flag.

Usage Examples

Streaming (Rust)

use quantwave_core::indicators::CDLENGULFING;
use quantwave_core::traits::Next;

let mut eng = CDLENGULFING::new();
for (o, h, l, c) in &ohlcv {
    let sig = eng.next((o, h, l, c));
    if sig != 0.0 { /* engulfing reversal event */ }
}

Streaming (Python)

from quantwave import CDLENGULFING
eng = CDLENGULFING()
for o, h, l, c in ohlcv:
    sig = eng.next((o, h, l, c))

Polars Batch (Python)

import polars as pl
df.lazy().with_columns(
    pl.col("open").ta.cdl_engulfing("open", "high", "low", "close").alias("engulfing")
).collect()

All surfaces bit-identical (Next contract + proptests).

Edge Cases & Limitations

  • Requires two complete bars.
  • False positives common in chop; always require trend context or structure confirmation.
  • Body-only vs. full-range engulfment definitions exist — QuantWave follows the TA-Lib body rule.
  • Volume expansion on the engulfing bar materially improves reliability.
  • Can be overridden by major news; combine with regime or liquidity filters.

Boundary Behavior

Condition Behavior
Warm-up Pattern functions emit 0 (no pattern) until enough bars exist.
period > len Short series returns all zeros (no pattern detected).
NaN inputs Bars with NaN OHLC are treated as no pattern (0).
Invalid params N/A for most candlestick patterns.
Empty data Empty input returns an empty integer series.

Sources & References

Primary Source: TA-Lib CDLENGULFING via quantwave-core/src/indicators/pattern.rs (talib_cdl! macro).

Visual: docs/gen_candle_previews.py (enhanced/regenerated 2026-05-31 IST under p1k6).

Context: Nison (1991) for shift-of-control psychology (no duplicated boilerplate text). MQL5 PA articles for structure confluence.

Provenance: Universal Next<T> trait guarantees identical results between streaming and Polars .ta.cdl_engulfing(...).