# Common Gap A Chart & Candlestick Patterns concept (Gap taxonomy) in the LuxAlgo Library, with 1 indicator implementation. ## What is a Common Gap? A common gap (also called an area or pattern gap) is the unremarkable member of the classical gap taxonomy: it opens inside an established [trading range](https://www.luxalgo.com/library/concept/trading-range/) or a still-forming pattern, on unexceptional volume, without breaking any structural boundary. In candlestick vocabulary any gap, this one included, is called a rising or falling window; the term does not distinguish gap types. Because nothing about the auction changed, the classical expectation is that it fills quickly and carries little forecasting weight. The four-part taxonomy, common, breakaway, runaway, exhaustion, comes from the classical bar-charting literature, where gap classification was a standard chapter by mid-century. The common gap is the taxonomy's baseline case, and its practical purpose is discipline: most gaps in most instruments are common, and the classification exists to stop traders from reading every open beyond the prior bar as the start of something. The label is partly retrospective. A gap earns 'common' from where it occurs (inside structure) and from what fails to follow it (no volume expansion, no follow-through). It functions as the null hypothesis of gap analysis: the classification a gap keeps until location, volume, or continuation argue for [breakaway](https://www.luxalgo.com/library/concept/breakaway-gap/), runaway, or exhaustion instead. Market structure decides how much work the concept gets. Cash equities gap at nearly every open, so common-gap bookkeeping (and the fill statistics that go with it) is a daily affair there; futures gap across session boundaries and weekends; and 24-hour crypto barely gaps at all except around venue outages and weekly candles on some platforms. Wherever they occur, unfilled common gaps leave small reference edges inside the range, minor cousins of the levels the [gap-fill](https://www.luxalgo.com/library/concept/gap-fill/) playbook tracks. ## How to identify a common gap The classification is location plus evidence, applied with a willingness to re-label. 1. Locate the gap relative to structure: a common gap opens inside an established range or pattern, breaking no boundary. 2. Check the volume: unexceptional turnover on the gap session supports the common label; expansion argues for something else. 3. Watch the first sessions for follow-through: drift and quick retracement fit the label, while sustained continuation contradicts it. 4. Treat the fill as the base case, price returning through the window, and note how routinely the instrument fills such gaps historically. 5. Keep the label provisional: a 'common' gap that refuses to fill while participation builds should be re-read as a breakaway in progress. 6. Until filled, mark the gap's edges as minor intraday references inside the range. ## How traders use it - Fill-side trades: because a common gap sits inside a range with no new commitment behind it, traders treat the [gap fill](https://www.luxalgo.com/library/concept/gap-fill/) as the base case and fade back toward the window. - As a discipline filter: classifying a gap as common prevents treating every gap open as a breakout signal, which matters in instruments that gap routinely. - Minor level bookkeeping: until filled, the gap's edges serve as small intraday references inside the range. - As statistics per instrument: fill frequency and typical fill time differ enough across symbols that gap-fade systems maintain per-instrument base rates rather than one universal assumption. - In scanner taxonomies: automated gap classifiers route each open by location and volume, sending common gaps to fade playbooks and boundary-breaking gaps to continuation ones, with misclassification handled by the follow-through rules. ## Common Gap vs related gap concepts - **Gap Fill** (https://www.luxalgo.com/library/concept/gap-fill/): The gap fill is the event, price re-trading the skipped span; the common gap is the classification that makes the fill the expected outcome. Fill statistics are the bridge between them, turning the classical expectation into per-instrument base rates. - **Candlestick Patterns** (https://www.luxalgo.com/library/concept/candlestick-patterns/): Candlestick vocabulary files every gap under rising and falling windows and reads them as support and resistance zones. The Western taxonomy splits gaps by role in the trend; the two systems overlap on the chart and differ in what they claim. ## FAQ ### Do common gaps always fill? No. Classical texts say most fill quickly, and inside a range that is the sensible default, but it is a tendency, not a rule. A common gap that refuses to fill while volume and follow-through build is telling you the classification was wrong, and the gap should be re-read as breakaway rather than faded. ### What is the difference between a common gap and a breakaway gap? Position and evidence. A common gap opens inside an established range on ordinary volume and tends to fill; a breakaway gap opens through the boundary of a structure on expanded volume and tends to run. Since both begin as an open beyond the prior bar's range, the distinction only firms up as follow-through arrives or fails. ### How does a common gap differ from an exhaustion gap? Location in the move. The common gap prints inside a range where nothing is trending; the exhaustion gap prints late in an extended trend as its last gasp, typically on heavy volume, and its fill marks the move's end rather than routine housekeeping. They share the tendency to fill; they differ completely in what the fill means. ### Do 24-hour markets have common gaps? Rarely in the classical sense: continuous trading leaves no scheduled opens to gap across, so crypto charts mostly show gaps only around exchange outages, thin weekend books, or on venues that pause. Futures keep session and weekend gaps, and CME-traded crypto futures famously accumulate weekend gaps that spot never printed. Gap analysis is therefore an equities-and-futures discipline first. ### How quickly do common gaps tend to fill? The classical claim is 'within a few sessions', and inside a rotational range the mechanics support it, since ordinary two-way trade re-visits nearby prices. Actual base rates vary by instrument, gap size, and regime, which is why systematic gap-faders measure fill frequency and median time-to-fill per symbol instead of quoting the folklore number. ### How is the gap-fill trade on a common gap structured? As a fade toward the window: entry against the gap's direction once early follow-through fails, target at or just inside the gap's far edge (the prior session's close), stop beyond the recent extreme, on the thesis that an inside-structure gap attracts no new commitment. The classification carries the risk: if the gap was actually breakaway, the stop is what limits the misread. ## Implementations in the Library - Rising & Falling Window Signals (LuxAlgo): https://www.luxalgo.com/library/indicator/rising-falling-window-signals/ ## Related concepts - Gap Fill: https://www.luxalgo.com/library/concept/gap-fill/ - Breakaway Gap: https://www.luxalgo.com/library/concept/breakaway-gap/ - Runaway Gap: https://www.luxalgo.com/library/concept/runaway-gap/ - Exhaustion Gap: https://www.luxalgo.com/library/concept/exhaustion-gap/ - Gap-and-go: https://www.luxalgo.com/library/concept/gap-and-go/ - Weekend Gap: https://www.luxalgo.com/library/concept/weekend-gap/ --- Source: https://www.luxalgo.com/library/concept/common-gap/ (LuxAlgo Library, the encyclopedia of trading & technical analysis). Free to use with attribution: https://www.luxalgo.com/library/license/