# Session Gap Fill

Session Gap Fill is an indicator on [Vela](https://vela.luxalgo.com/chart), our next-generation charting platform, written in Pine Script®.

Session Gap Fill marks every opening gap between trading sessions, tracks whether each one fills, and compiles the outcomes into an on-chart dashboard: gap direction share, fill rates, post-fill reversals, and average bars to fill. Overlapping and non-overlapping gaps can be studied separately - for day traders who want the open quantified before they trade it.

- Indicator in the LuxAlgo Library, by LuxAlgo, published Oct 8, 2025.
- Access: free.
- Concepts: [Gap Fill](https://www.luxalgo.com/library/concept/gap-fill/) (primary), [Trading Sessions](https://www.luxalgo.com/library/concept/trading-sessions/)
- Open on Vela: https://vela.luxalgo.com/chart?pineScriptCodeId=cmpwn5mkn007xvhsgs9uh8v0t
- Page: https://www.luxalgo.com/library/indicator/session-gap-fill/

**Session Gap Fill** watches the handoff between trading sessions. Whenever a session opens away from the previous session's closing price, it marks a bullish gap (open above the prior close) or a bearish gap (open below), then follows each one to record whether price returns to that prior close - the [gap-fill](https://www.luxalgo.com/library/concept/gap-fill/) event - or leaves the gap standing. What emerges is a statistical picture of how your market treats its opening dislocations.

## How to Trade the Session Gap Fill?

- **Filled vs unfilled**: a quick fill shows the market rejecting the new opening prices, while a gap that stays open signals acceptance of the sentiment shift it expressed. The reaction, not the gap itself, is the information.
- **Overlapping vs non-overlapping**: overlapping gaps - where the new session's first bar shares price levels with the prior bar - behave differently from clean breaks, and the Gap Type filter lets you study each population on its own.
- **Dashboard columns**: Gaps (bullish vs bearish share), Filled (fill rate by direction), Reversed (how often a filled gap turns back in the gap's original direction), and Bars Avg. (typical bars until fill).

## Session Gap Fill Settings

- **Gap Type**: analyze all gaps, overlapping only, or non-overlapping only.
- **Dashboard / Position / Size**: toggle the statistics panel, place it, and scale it.
- **Style toggles**: visibility and colors for filled bullish, filled bearish, and unfilled gaps, plus the Max Deviation Level and Open Price Level overlays.

## Frequently Asked Questions

### How exactly is a gap detected?
The indicator compares a session's first-bar open with the previous session's last-bar close. Any difference registers as a gap - bullish when the open prints higher, bearish when it prints lower.

### Can the statistics tell me which gaps to fade?
They describe tendencies, not certainties. Fill rates, reversal rates, and Bars Avg. show how each gap type has resolved on your instrument - context for judging whether fading or following the open has been the more common outcome.

### Is Session Gap Fill free to use?
Yes - it belongs to the library's free collection. If session statistics are your thing, [Session Streaks](https://www.luxalgo.com/library/indicator/session-streaks/) gives the same data-driven treatment to session direction itself. You can also copy the source code from this page and run it anywhere Pine Script® runs.

## Related indicators

- [Gap Fill Breakouts](https://www.luxalgo.com/library/indicator/gap-fill-breakouts/) (Gap Fill): markdown at https://www.luxalgo.com/library/indicator/gap-fill-breakouts.md
- [Rising & Falling Window Signals](https://www.luxalgo.com/library/indicator/rising-falling-window-signals/) (Gap Fill): markdown at https://www.luxalgo.com/library/indicator/rising-falling-window-signals.md
- [Sessions](https://www.luxalgo.com/library/indicator/sessions/) (Trading Sessions): markdown at https://www.luxalgo.com/library/indicator/sessions.md
- [Session Streaks](https://www.luxalgo.com/library/indicator/session-streaks/) (Trading Sessions): markdown at https://www.luxalgo.com/library/indicator/session-streaks.md
- [Breakaway Fair Value Gaps](https://www.luxalgo.com/library/indicator/breakaway-fair-value-gaps/) (Breakaway Gap): markdown at https://www.luxalgo.com/library/indicator/breakaway-fair-value-gaps.md
- [Exhaustion Gap](https://www.luxalgo.com/library/indicator/exhaustion-gap/) (Chart & Candlestick Patterns): markdown at https://www.luxalgo.com/library/indicator/exhaustion-gap.md
- [Runaway Gap](https://www.luxalgo.com/library/indicator/runaway-gap/) (Chart & Candlestick Patterns): markdown at https://www.luxalgo.com/library/indicator/runaway-gap.md
- [Ascending Base](https://www.luxalgo.com/library/indicator/ascending-base/) (Chart & Candlestick Patterns): markdown at https://www.luxalgo.com/library/indicator/ascending-base.md

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Source: https://www.luxalgo.com/library/indicator/session-gap-fill/ (LuxAlgo Library). Free to use with attribution: https://www.luxalgo.com/library/license/