"Gaps fill" is one of the first things a new trader hears. Most of the time they don't, at least not the same day. Fewer than half of the gaps of 0.5% or more got back to the prior close before the session ended.
The bigger the gap, the less often it filled. The chart above has every size.
The biggest gaps almost never came back that day. Gaps of 4% or more filled only 9.1% of the time.
Direction barely matters. Up gaps and down gaps filled at about the same rate.
What to do with it
Most of the gaps that fill do it before lunch. Of the 0.5%+ gaps that filled at all, 79.6% were done by noon.
Share of gaps of 0.5% or more back at the prior close, by time of day, March 2023 to October 2026
| Time | Share of gaps of 0.5% or more back at the prior close, by time of day |
|---|---|
| 9:30 AM | 0.0% |
| 10:00 AM | 18.3% |
| 10:30 AM | 24.9% |
| 11:00 AM | 29.0% |
| 11:30 AM | 31.4% |
| 12:00 PM | 33.3% |
| 12:30 PM | 34.3% |
| 1:00 PM | 35.7% |
| 1:30 PM | 37.1% |
| 2:00 PM | 38.1% |
| 2:30 PM | 39.0% |
| 3:00 PM | 39.8% |
| 3:30 PM | 40.4% |
| 4:00 PM | 41.8% |
A gap still open at noon rarely fills by the close. Only 12.8% of them did.
So if you fade a gap for the fill, the morning tells you most of what you need. A gap that hasn't come back by lunch is a trade on something other than the fill, and it needs its own reason and its own stop.
An example day
Nvidia on October 6, 2026 was the rare kind. It opened 1.3% above the prior close and was still open at noon.
It did fill in the end, on the 3:40 PM candle.
Play it from the open in Market Replay and see whether you'd have held a fade that long.
| Gap size | Gaps | Filled by 10:30 AM | Filled by noon | Filled by the close |
|---|---|---|---|---|
| Under 0.5% | 3,282 | 68.2% | 74.3% | 79.4% |
| 0.5% to 1% | 1,546 | 33.7% | 43.2% | 52.5% |
| 1% to 2% | 935 | 16.8% | 24.2% | 32.3% |
| 2% to 4% | 288 | 10.1% | 17.4% | 24.3% |
| 4% or more | 77 | 3.9% | 5.2% | 9.1% |
| 0.5% or more | 2,846 | 24.9% | 33.3% | 41.8% |
How we counted
Regular-hours 5-minute bars for SPY, QQQ, IWM, Apple, Microsoft, Meta and Nvidia from March 2023 to October 2026, half days left out. The gap is the first trade of the session against the prior session's last trade, and it counts as filled when price traded back to that prior close in the same session. A gap that filled on a later day counts as not filled here. Prices are TraderPier's own trade data, as traded and not adjusted, and Nvidia's June 2024 split day is left out. These are seven large names that mostly rose over this stretch, so smaller stocks may behave differently.
Questions
Do gaps always fill?
No. Of the gaps of 0.5% or more, 58.2% never got back to the prior close the same day.
Do gap downs fill as often as gap ups?
About as often. Down gaps of 0.5% or more filled the same day 42.4% of the time.
How often do gaps fill in the first hour?
Gaps of 0.5% or more filled in the first hour 24.9% of the time.
Does this count gaps that fill days later?
No. Only the same session counts, so a gap that filled the next week shows up here as not filled.