GAP FILL PROBABILITY
Not every gap is the same gap. Size it, classify it, and check it against real historical fill rates before you decide whether to fade it.
Size Today's Gap
Not All Gaps Behave the Same
A gap isn't automatically a signal to fade or to chase — what kind of gap it is matters more than the fact that it exists. The same 0.5% gap can mean completely different things depending on where it happens in the broader trend.
What The Data Actually Shows
| Gap size | Same-day fill rate |
|---|---|
| Tiny (< 0.3× ATR) | ~93% with ORB confirmation |
| NQ baseline (all sizes) | ~60% overall |
| Gap down vs. gap up | ~62% vs. ~59% |
| Common gaps (no catalyst) | ~70–75% |
| Median time to fill (tiny gap) | ~7 minutes |
| Median time to fill (small gap) | ~74 minutes |
Figures pulled from published backtests covering roughly 2,600–2,800 ES/NQ trading days (2014–2025) and a separate 25-year ES study — these are historical averages, not live-calculated from current data, and are not a guarantee for any single day. Bigger gaps and gaps with a real news catalyst (earnings, Fed decisions, geopolitical events) fill less reliably than this table implies — treat these as a starting reference, not a rule.