What is a gap, and why do stocks gap?
A gap is the empty space on a chart between one session's close and the next session's open. Regular trading in US stocks runs from 9:30 a.m. to 4:00 p.m. ET, but news does not wait. Companies usually report earnings before the open or after the close, and major data such as the jobs report and CPI come out at 8:30 a.m. ET. Pre-market trading on the exchanges starts at 4:00 a.m. ET, so by the opening bell the price has often moved well away from yesterday's close.
Hypothetical: a stock closes at $50.00, reports earnings after the close and trades higher overnight. It opens at $53.00, a gap up of $3.00, or 6%. A gap down is the mirror image: bad news, and the stock opens below the prior close. Analyst upgrades and downgrades, deal news and big overnight moves in index futures cause gaps too. The US stock market hours guide lists every session in your time zone.
Full gap vs partial gap: which levels matter?
Measure every gap against three prices from the prior day: the close, the high and the low. A partial gap up opens above the prior close but still inside the prior day's range, below its high. A full gap up opens above the prior high, clear of every price traded the day before. Gaps down work the same way with the prior low. Definitions vary a little between sources; this guide uses these.
Hypothetical: the prior day traded between $48.60 and $50.40 and closed at $50.00. An open at $50.30 is a partial gap up of only $0.30, with the prior high just $0.10 overhead as the first resistance. An open at $53.00 is a full gap up: the prior high at $50.40 now sits below as the first support on the way down, and the prior close at $50.00 just under it marks where the gap would be filled.
These old prices work as levels because so many traders watch them. In the drawing, picture the support zone as the prior day's high under a full gap up: a fade that dips into it and holds can turn back up, the same reaction you see at any support and resistance level.
Gap and go: how to trade a gap that keeps going
Gap and go is the continuation play: the gap holds, buyers stay in control and price pushes higher, as in the left panel of the drawing at the top. Look for evidence first: a real catalyst, relative volume well above normal, price holding above the pre-market high or the opening range high, and price staying above VWAP. The trigger is a closed candle, not a tick through the high.
Hypothetical, using the $53.00 open: the pre-market high is $53.40 and the first 15 minutes trade between $52.80 and $53.60. At 9:50 a.m. ET a 5-minute candle closes at $53.70, above both. Buy at $53.70 with the stop at the range low, $52.80: a risk of $0.90. A 2R target sits at $55.50. A $20,000 account risking 0.5% accepts $100, and $100 ÷ $0.90 = 111 shares.
The failure case: two candles after entry, price slips back inside the range and trades down through $52.80. The stop fills there, a loss of $99.90 plus costs (111 × $0.90), or −1R. A breakout that falls straight back into the range is how this setup usually fails, and it is often where a fade begins. Take the stop instead of hoping it turns.
Gap fill: how to trade a gap that fades
Gap fill, or fading the gap, is the opposite bet: the open overshoots, early buyers take profits, and price drifts back toward the prior close, as in the right panel of the drawing at the top. A gap up is filled when price trades back down to the prior close; a gap down, when it trades back up to it. Many traders fade only gaps without a clear catalyst, or small partial gaps, and stay away from full gaps driven by big news.
Hypothetical, a different day: the stock opens at $53.00 but never reaches the $53.40 pre-market high. The first 15 minutes trade between $52.60 and $53.30, then a 5-minute candle closes at $52.50, below the range low and below VWAP. Short at $52.50 with the stop at $53.35, just above the range high: a risk of $0.85. The full fill at $50.00 is $2.50 away, about 2.9R, but the prior high at $50.40 is support on the way, so a first target at $50.45, about 2.4R, is more honest.
The failure case: a fade is a bet against strength. If the news is strong, price can reclaim the range high, run through the pre-market high and never look back. The stop at $53.35 keeps that loss near −1R. A fade held with no stop, because "gaps always fill", can lose many times the planned risk. Short selling also needs an account that allows it and shares available to borrow.
Pre-market high, low and relative volume: what to check before the open
Do the homework before 9:30 a.m. ET. On an intraday TradingView chart, switch to extended hours (Settings, Symbol, Session, or the session button in the bottom toolbar), mark the pre-market high and low with horizontal lines, then switch back to regular hours if that is the session you trade. The best TradingView settings guide explains why.
Relative volume (RVOL) compares today's volume with the average volume at the same point in past sessions, so 1 is a normal day and 2 is twice the usual volume for that time. TradingView's built-in Relative Volume at Time indicator measures it this way. A big gap on light relative volume is easier to fade; a big gap on heavy relative volume is harder to stand in front of.
- Catalyst: what caused the gap? Earnings, guidance, a deal or a downgrade weighs more than no news at all.
- Size and type: how big is the gap, and is it partial or full?
- Levels: the prior close, prior high and low, pre-market high and low, written down with prices.
- Relative volume: is the stock trading far more than usual for this time of day?
- Spread: pre-market quotes can be thin, and spreads are wide right after the open. Is the stock liquid enough for your stop?
- The plan: the price that confirms gap and go, the price that confirms a fade, and where each stop goes.
Why wait for the opening range before trading a gap?
The first minutes after the open are the noisiest of the day. The opening auction clears a night of orders in one print, spreads are wide and the gap is still being repriced. Many gap traders let the first 5 or 15 minutes form an opening range, then act only on a candle that closes outside it.
With a 15-minute range, you wait from 9:30 to 9:45 a.m. ET. A 5-minute close above the range high, ideally above the pre-market high too, supports gap and go. A close below the range low, especially back under VWAP, supports a fade. A close back inside the range is no trade. The opening range breakout guide covers the method in depth.
In the gap-and-go example, the range was $52.80 to $53.60. A trader who bought the first spike at $53.55 at 9:31 with a tight stop at $53.25 was stopped out when price dipped to $52.80 at 9:38, twelve minutes before the real breakout. Waiting costs a little price and buys a stop at a level that means something.
UpTickFlow, our invite-only TradingView indicator, follows the same discipline: it stays quiet in the first minutes after the open, waits for a candle to close at a level, then draws an entry, a stop and a target before the trade and scores the setup from 0 to 100. It is not a gap scanner and it does not place trades; treat it as a second check on a plan you already made. See how it works.
Stops, position size and gap risk
Put the stop where the idea is wrong. For gap and go, that is under the opening range low, or under the pre-market high if you bought its breakout. For a fade, it is above the opening range high or the high of the day. Then size from the stop: shares = dollar risk ÷ distance to stop, as the position size calculator does, so a full loss stays close to your fixed risk.
Know the limit of a stop order. Once triggered, it becomes a market order and fills at the next available price, which in a fast market can be well past the stop. A gap is the extreme case. Hypothetical: you hold 125 shares overnight, bought at $52.00 with a stop at $51.20, risking $100. Bad news hits after the close and the stock opens at $48.00. The stop triggers at the open and fills near $48.00: a loss of about $500, or 5R, not 1R.
A stop-limit order avoids a fill far below your price, but it may not fill at all, and then you still hold the stock while it keeps falling. The simplest defence is to be flat before the close and before earnings, or to size any overnight position so that even a large gap is survivable. The stop loss and take profit and order types guides go deeper.
Do all gaps fill? The myth behind the saying
"All gaps fill" is one of the most repeated sayings in trading, and it is not a rule. Many gaps do trade back to the prior close, sometimes within hours, sometimes weeks later. Others stay open for months or years. A claim with no time limit can never be proven wrong, which makes it useless for a trade that needs a stop and a size.
Classic technical analysis sorts gaps into four types. Common gaps happen inside a sideways range and are often filled quickly. Breakaway gaps launch price out of a range or a chart pattern, often on heavy volume, and can stay unfilled for a long time. Runaway, or continuation, gaps appear in the middle of a strong trend. Exhaustion gaps come near the end of a long move and are often filled soon after. Which type it was is usually clear only in hindsight.
Hypothetical: a stock gaps from $50.00 to $53.00 on strong earnings. A trader shorts at $53.00, sure the gap will fill, with no stop. Over the following weeks the stock climbs to $60.00. Down $7.00 a share and still waiting for $50.00, that trader is not managing a trade, just hoping. A fade needs evidence on the chart and a stop, like any other trade.
Common gap trading mistakes
Most of these happen near the open, when a big gap feels most urgent, and they are especially common in the first months of day trading.
- Buying the first green candle at 9:31 instead of waiting for the opening range and a closed candle.
- Fading every gap because "gaps fill", even a full gap on real news and heavy relative volume.
- Ignoring the prior day's high and low, the first levels a gap runs into.
- Trading the same share count on a gap day as on a quiet day, when the stop has to be wider.
- Holding a day trade overnight or through earnings and expecting the stop to cap the loss.
- Trading a thin stock with a wide spread, so the spread eats a large part of the risk before price moves.