Research
Gap Study
TheDesperateTrader.com· do stock gaps actually fill?
When a stock gaps overnight, what does it actually do next - fill the gap, keep running, or fade? Measured from our own daily history and always shown against a normal trading day, because the gap size alone is just volatility.
466 trading days3.9M tradeable daysopen→close horizon
Read this first
A bigger gap is not a bigger edge. The gaps traders chase hardest fade the most - stocks that gapped up 10%+ closed just -1.09% from their open on average (a normal day: -0.02%), and 27% of them filled the gap. The Gap Study shows that plainly, so you fade or size on reality instead of the highlight reel.
Featured cohort · how to read a card
Gap up 10%+
Opened at least 10% above the prior close
Fades the gapdays15k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
+16.26%
Avg open→close
−1.09%
Closed green
40.5%
Filled the gap26.7%
Share that traded back down to the prior close at some point during the day.
What this means rules-based, no AI guesswork
- On average it gives back the pop: the typical day closed −1.09% from its open versus −0.02% for a normal day.
- 27% of these gap-ups traded back down to the prior close at some point - the gap "filled".
- Fewer than half (41%) actually closed green from the open, so buying the open was a coin flip at best.
All gap cohorts · biggest gaps first
Gap up 20%+
Opened at least 20% above the prior close
Fades the gapdays3k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
+26.90%
Avg open→close
−0.29%
Closed green
41.6%
Filled the gap18.6%
Share that traded back down to the prior close at some point during the day.
Gap down 10%+
Opened at least 10% below the prior close
No net edgedays12k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
−15.86%
Avg open→close
−0.10%
Closed green
48.7%
Filled the gap16.8%
Share that traded back up to the prior close at some point during the day.
Gap up 5%+
Opened at least 5% above the prior close
Fades the gapdays57k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
+9.20%
Avg open→close
−0.81%
Closed green
40.6%
Filled the gap35.4%
Share that traded back down to the prior close at some point during the day.
Gap down 5%+
Opened at least 5% below the prior close
Bounces from opendays50k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
−8.92%
Avg open→close
+0.40%
Closed green
51.3%
Filled the gap30.0%
Share that traded back up to the prior close at some point during the day.
Market baseline
All tradeable days
Baselinedays3.86M
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg open→close
−0.02%
Closed green
48.1%
Method & honest limits
- The gap. Each day’s open versus the prior day’s close. We read what the stock did that day: whether it retraced to the prior close (filled), where it closed relative to its open, and how it compared to a normal day.
- Gap fill is not profit. A gap filling means the price touched the prior close at some point - a volatility fact, not a trade you would necessarily capture.
- Continuation decides the verdict. A cohort “keeps running” only if its average open-to-close move beats a normal day. On this window, the popular gap-and-go setups do not.
- Tradeable names only, splits excluded. Filtered to a liquidity floor (at least $1, real dollar-volume). The raw data is unadjusted for splits, so extreme moves (40%+) are dropped as likely split artifacts - a few smaller split gaps can still leak into the gap-down cohorts.
- Refreshed nightly. Base rates, honestly reported. Not advice, not a performance promise, and not personalized.
Related study
Setup Lab · do intraday setups actually work? →
The intraday companion to this study: momentum pops, RVOL spikes, breakouts and VWAP reclaims, measured the same honest way - upside, downside and net versus the market baseline.
Frequently asked questions
What a stock actually does after it gaps, measured honestly - fill rate, continuation, and how it stacks up against a normal day.
- Do stock gaps actually fill?
- Often, but not because gaps are magic. Measured over our own daily history, a large share of gap-ups traded back down to the prior close at some point during the day, and gap-downs traded back up - the "fill". But a gap filling intraday is mostly a function of ordinary volatility, not a reliable signal. The Gap Study shows the fill rate for each gap size beside what the day actually did.
- Does a gap up keep running ("gap and go")?
- Barely, and less as the gap gets bigger. On our history the average gap-up closed only a fraction of a percent from its open - roughly the same as a normal day - and the biggest gaps (10%+, 20%+) faded MORE, not less. Fewer than half closed green from the open. A big gap is volatility, not an edge.
- How is a gap judged to "keep running" or "fade"?
- Only on the average open-to-close move versus a normal trading day - never on the size of the gap. A cohort reads "keeps running" only if it closes meaningfully green from the open and beats the market baseline by a real margin; otherwise it is "no net edge" or "fades the gap".
- What data is this measured on?
- Our own daily bar history across thousands of symbols, filtered to a tradeable-liquidity floor (at least $1 and real dollar-volume) so the base rates describe names you could realistically act on. Because the raw data is unadjusted for splits, extreme overnight moves (40%+) are excluded as likely split artifacts. Base rates, not advice.
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