Types of Gaps in Trading (and Whether They Fill)

A gap is the empty space left when a stock opens away from yesterday's close because something happened overnight: earnings, a downgrade, a headline. Every trader asks two questions when they see one. What kind of gap is this, and will it fill? A gap that punches out of a base on heavy volume and a gap at the top of a vertical run leave the same hole on the chart and mean opposite things.

Quick Answer

What Is a Gap in Trading?

A gap is empty space on the chart where price opened away from the prior close, with no trades in between. A gap up opens above yesterday's close, a gap down opens below it. Gap size is the open minus the prior close, divided by the prior close, so a stock that closed at 50.00 and opens at 51.50 gapped 3%. Investopedia's gap entry has the textbook version.

Two more terms matter once you get to fills. A full gap opens beyond the prior day's high (or low), clearing the whole range. A partial gap opens past the prior close but still inside the prior range, and partial gaps fill more often, as the numbers below show.

Gaps come from new information hitting a closed market: earnings, guidance, upgrades and downgrades, sector news, a broad sentiment swing. Thin liquidity can gap a stock too. The gap is only the footprint of that event. What makes it tradable is where it sits and what volume does once the market opens and votes on the overnight repricing.

What Are the Four Types of Gaps?

Traders sort gaps into four classic types. Like most chart patterns, a gap is read by context: where it shows up in a move, and the volume behind it, decide which one you're looking at. Some lists add a fifth, the island reversal, a cluster of bars cut off by gaps on both sides.

The breakaway gap is the one momentum traders care about most, because it's a gap and a breakout at once. Price gaps out of a base on strong volume and clears a level it had been stuck under. If you've read the AI breakout detection guide, a breakaway gap is a breakout that happened overnight, and the same read applies: volume and level quality separate a real one from a fake.

The runaway gap is also called a measuring gap, because it tends to print around the middle of a move. The rule of thumb projects the rest of the move by adding the distance from the breakout to the gap on top of the gap. Treat that as rough.

One Trend, Three Gaps (Illustrative)

A made-up example with round numbers, not a real ticker or date. A stock bases between 20 and 22 for six weeks, then gaps from 22 to 23.50 on three times its usual volume. That's the breakaway. Two weeks later it gaps again, 27.40 to 28.60, on above-average volume, and the gap holds as support on the next pullback. That's the runaway. The move started near 22 and the runaway sits about 6 points higher, so the measuring rule points to roughly 34. At 33, after a near-vertical week, it gaps to 35 on the tallest volume bar of the run, never makes a new high, and closes back inside the gap two days later. That's exhaustion. Same empty space, three different messages.

What Is an Exhaustion Gap?

The exhaustion gap prints at the end of a move instead of the start. Price has already run hard, it's stretched far from anything it could lean on, and then it gaps one more time on the heaviest volume of the run. That's the last wave of traders getting in. Once they're in, nobody is left to push.

It runs in both directions, which most gap explainers leave out. The bearish exhaustion gap is a gap up at the top of an uptrend, the last buyers paying the worst price of the move, with a reversal down more likely than another leg up. The bullish exhaustion gap is the mirror, a gap down at the bottom of a downtrend as the last sellers give up. The label describes what tends to come next, which is why a bearish exhaustion gap is a gap up.

The bullish version gets traded far less, because buying a gap down into a washed-out chart feels worse than chasing a gap up into a strong one. The bearish side has the opposite problem. A gap up at the top of a run looks like strength right when it's least likely to be, the same trap covered in the piece on spotting an overextended chart before you enter.

What an Exhaustion Gap Actually Looks Like

A made-up shape with placeholder numbers, not a real name on a real date. A stock runs from roughly 40 to 62 over three weeks, pulling further from its rising 20 EMA on every leg and never building a base. Then it gaps open at 66, 4% above the 63.40 close, and the opening volume bar is the tallest of the run.

The first half hour makes a high at 66.80 that never gets taken out. Price grinds sideways, rolls over in the afternoon, and closes at 63.10, a red candle that swallowed the whole gap. The next morning it can't get back above 64. Extended run, climactic gap, close near the low, no new high. Flip every direction and you have the bullish version.

None of that is callable on the open. At 9:31 the chart looks almost identical to a runaway gap with plenty left in it. The run and the volume spike tilt the odds toward exhaustion, and that's all they do. A shooting star printing at the high of the gap day tightens the read without confirming it.

How Do You Confirm an Exhaustion Gap?

"This might be exhaustion" and "that was exhaustion" are separated by a session or two of follow-through. These reads move you from one to the other.

• No new high in the next session or two
  The simplest tell. If the sessions after a gap up at the top of a run can't take out the gap-day high, everyone who bought the gap is underwater and the move has stopped working. For a bullish exhaustion gap, read it the other way: no new low.
• A reversal candle closes back through the gap
  A session that trades into the gap and closes below its bottom edge has undone the overnight repricing in public. It's the clearest single confirmation, and it's where most fades get entered. A bearish engulfing candle that swallows the gap day is the textbook version.
• Climactic volume on the gap bar itself
  Climactic volume is what makes it exhaustion. A gap on ordinary volume is more likely a common or runaway gap, and the last-wave story doesn't apply.
• Volume dries up right after
  The sessions after a real exhaustion gap usually go quiet, because everyone who wanted in got in on the gap. Volume that keeps building on higher closes says the opposite.
• What kills the read
  New highs on continued heavy volume, with the gap holding as support. That's a runaway gap doing its job. Staying in the fade to be proven right later is how a small loss turns into a large one.

Three of those need the next day or two, so a confirmed exhaustion gap is mostly a label you apply after the fact. In real time you're weighing odds, and a fade gets sized like a probability, not a top call. An AI read of your screenshot can see the stretched run and the volume spike. It can't see tomorrow's follow-through, because tomorrow isn't in the picture.

How Do You Tell the Gap Types Apart?

Volume and location do almost all the work, because the gaps themselves can look identical. A gap on quiet volume inside a range is a common gap. A heavy-volume gap out of a base near the start of a trend is a breakaway. The biggest, most climactic gap after a long vertical run is the exhaustion gap. The same big volume bar means "real" at the bottom of a base and "watch out" at the top of a run.

The deep dive on how AI reads volume to confirm momentum trades applies directly here. The gap tells you something happened. The volume tells you whether anyone is still behind it.

How Big Does a Gap Need to Be to Matter?

Size is the second filter. A 0.4% gap and a 14% gap can both look like a breakaway and still be completely different trades. Pre-market scanners let you set a minimum gap percentage so you only read the handful of names that actually moved.

These bands are a rough convention, and they shift by stock. A 2% gap on a slow large cap can be a real event, while 2% on a stock that swings 10% a day is noise. Measuring the gap against the stock's own average true range handles that, and it's how the futures study below sorts gaps. Size also drives the fill odds. The smaller the gap, the more likely it fills.

Gaps on Other Timeframes and Markets

Most gaps worth trading are overnight, the daily open against the prior close. A visible gap on a weekly or monthly chart needs the whole bar to trade clear of the prior bar's range, so those are rare. One catch on intraday charts: with extended hours turned on, the premarket session (and the prior evening's after-hours) fills in the space, and the regular-session gap can disappear. If you want the gap read, keep the prior session's close in the screenshot.

Other markets gap on their own schedules. ES and NQ trade nearly around the clock on weekdays (the futures session hours guide has the times), so the overnight move prints as ordinary candles and the gap you see on SPY at the open is mostly that move catching up. The stock futures explainer shows how fair value turns that into the opening gap.

Spot forex runs 24 hours on weekdays, so its gaps mostly come at the Sunday open. Spot crypto never closes, so it barely gaps. CME bitcoin futures used to gap over their weekend break, the "CME gaps" crypto traders watch, but CME's crypto futures now trade every day, as the guide to what trades on weekends covers.

What Is a Gap Fill, and Do Gaps Always Fill?

A gap fill is when price trades back to the level it gapped away from, usually the prior session's close: the low reaching down to it after a gap up, or the high reaching up to it after a gap down. A partial fill covers only part of the gap before turning, and the 50% mark, the gap's midpoint, is the checkpoint most traders watch. Some sources measure a fill to the prior day's high or low instead of the close, and some traders only count a close back through the level, not a touch, so fill stats aren't always comparable.

Gaps don't always fill. Common and exhaustion gaps fill often, because there was little conviction behind them. Breakaway and runaway gaps often don't fill soon, because real demand is behind them and the stock keeps going. "Every gap fills eventually" only works if you're willing to wait years, and some never do.

The gaps that do fill tend to fill for two reasons. The overnight move often overshoots, and once the market opens and digests the news, some of it comes back. And nothing traded inside the gap, so there are no earlier buyers or sellers in that zone to slow price down until it reaches the far edge. That's also why a fill tends to finish once it gets going: on NQ futures from 2015 to 2025, 68.0% of gaps reached the 75% mark by the close and 60.3% went all the way.

How long a fill takes ranges from minutes to years, or never. On NQ futures most of it happens early: 43.3% of gaps filled completely in the first hour. A breakaway gap on a stock that re-rated on earnings can stay open for months, or for good.

How Often Do Gaps Fill?

The "70-80% of gaps fill" line gets repeated a lot, and so do "80%" and "91.4%". None of those show a method you can check. Two sources publish measured fill rates with the method shown. thetrading.tools tracks every SPY gap since 1993 and counts a trade back to the prior close as a fill. Its figures here are as of October 23, 2026, and the tool recomputes them daily. tradingstats.net studied 2,791 regular-hours sessions of NQ futures from 2015 to 2025, same session only. Both measure index products by gap size. Neither measures by gap type.

Size does most of the work in that table. Most tiny gaps fill the same day, big ones mostly don't. Some of that is arithmetic, as thetrading.tools points out: a 0.15% gap only needs a 0.15% wiggle to fill, and the average day moves several times that, so a high fill rate on small gaps isn't an edge by itself. And a single stock gapping 6% on earnings is not SPY gapping 0.2% on nothing. Use these as base rates for index products, not as fill odds for your gapper.

What Role Does Volume Play in Gap Filling?

Next to size and where the open lands, volume is the main read on whether a gap runs or fills. Heavy volume in the gap's direction, on the gap bar and the bars after it, means real buyers (or sellers) are behind the move. That's the continuation case, breakaway and runaway gaps. A gap on light volume has nobody defending it, which makes it the fill candidate. Watch the fill attempt too. A push back into the gap on rising volume tends to carry through to the prior close, while one that drifts in on shrinking volume often stalls short of it.

Sources disagree on one point, the volume on an exhaustion gap. Most call it climactic, the biggest bar of the run. A couple of broker guides say exhaustion gaps come on low volume, and another says volume falls after the gap. Both can be true in sequence, which is how this page reads it: a climactic gap bar, then volume drying up because nobody is left to buy. Volatility counts too. In the same tradingstats.net study, NQ gaps filled by the close 63.2% of the time in low-volatility regimes and 56.3% in high-volatility ones, and gaps that were large against ATR filled far less often.

How Do You Trade a Gap?

Traders use a gap three ways, and two of them point in opposite directions, which is why the type comes first. The gap isn't a signal by itself.

Gap-and-go is the momentum play. A breakaway gap holds above the prior close with volume behind it, and you trade the continuation with a stop below the gap or the opening range. If you miss the open, the retest is the calmer version. The level a breakaway gap broke, and the top of the gap itself, tend to flip into support (resistance after a gap down), so traders wait for a pullback into that zone on lighter volume and buy when it holds. It's the same pullback entry the momentum trading strategy guide is built around. The fade is the third play: after an exhaustion gap, traders bet on a fill back toward the prior close.

The trap to respect is a failed gap-and-go, where a gap up sucks in buyers, then rolls back through its own low. That's the same mechanism as the bull trap and bear trap patterns. Knowing where the gap sits against your support and resistance levels keeps you on the right side of it. And if you hold overnight, a stop can't protect you from the next gap, because the open can print well past it, as the stop loss guide explains.

How Does AI Read a Gap?

SnapPChart has no gap detector. There's no gap-type label and no gap-size number. It sees the gap the way it sees the rest of the chart: where price opened against the prior range and the levels, the volume on that candle (if the volume pane is in the shot), and how far the move has stretched from its averages. It only sees the prior close if your screenshot includes the prior session.

From there it grades the setup as a momentum continuation in the direction of the established trend and makes one of three calls: take the trade, wait for a pullback, or skip it. It doesn't take reversals, so it never calls a counter-trend fade, like shorting a gap up at the top of an uptrend. A stretched run into a gap usually draws the extended-move flag, which is chase risk, and that pushes the call toward a wait or a skip instead of a short against the trend. The retest play above is the shape its wait-for-a-pullback call describes. Its rules treat the stretched move you most want to chase as a reason to wait.

It doesn't scan for gappers, so find them with a scanner or your broker's movers list (the AI momentum scanner guide covers that step). It doesn't predict fills. And it has no live data, Level 2, tape or news, because none of that lives in a screenshot. What you get is the same structure read as any AI chart analysis, applied to a chart that happens to have a gap in it. No grade changes the base risk that FINRA's investor guide to how stocks work spells out: stock prices "can go down, sometimes quite dramatically."

Where Gap Trades Go Wrong

Almost every gap mistake is a version of trading the empty space without naming the type.

• Shorting a breakaway gap because gaps fill
  Fading a heavy-volume gap that just cleared a key level, on faith that all gaps fill. Breakaway gaps often don't fill soon. This is the type you trade with, not against.
• Chasing an exhaustion gap as a breakout
  Buying the biggest, most climactic gap after a long vertical run, mistaking a last gasp for a fresh start. That gap often fills and can mark the top.
• Ignoring the volume on the gap candle
  Trading a gap on the size of the empty space alone. A big gap on quiet volume is weaker than a smaller gap on heavy volume.
• Treating the fill as a guarantee
  Sizing a fade as if the gap must come back. Gaps over 1% on SPY mostly don't fill the same day, and a breakaway on a stock can run for weeks without filling.
• Forgetting the gap is a level
  Watching the gap as empty space instead of support or resistance. The prior close and the gap edges are levels price reacts to, and a gap that fails back through its own low is the warning the move had no demand.