Gap and Go vs Gap Fill in Futures Trading: A Framework for Opening Gaps

The most expensive habit on a gap morning is deciding what the gap will do before the market has shown you anything. Short a gap that keeps running and you take stop after stop. Buy a gap that is about to fill and you're long at the worst price of the morning. The framework below won't predict gaps. It gives you a way to sort them, wait for evidence, and size the risk in dollars.

What a futures gap actually is

ES and NQ trade through the night, so there's no hole in price. A gap in this context is the difference between the prior regular session close and the price at the 9:30 AM ET open of the regular session (RTH). Pick one convention for the prior close and stay with it, because a 4:00 PM ET cash close and a later futures print can differ. Holidays and early closes also change the schedule, so check the CME calendar.

Large gaps tend to follow information that arrived after the close: an 8:30 AM ET economic release, an overseas move, an earnings surprise from a mega-cap company, or geopolitical news. A scheduled event during RTH, like an afternoon Fed announcement, doesn't create the next morning's gap by itself, though the reaction to it can.

Four rough categories

The size bands below are my starting framework, not tested thresholds. Scale them to current volatility, because 5 ES points means something different in a quiet month than in a wild one. For reference, 5 ES points is $250 per contract ($25 per MES) and 20 NQ points is $400 per NQ contract ($40 per MNQ).

• Small, no catalyst (roughly under 5 ES points). Default lean is toward a fill, but I wouldn't act until the opening range agrees.
• Medium, unclear catalyst (roughly 5 to 15 points). No lean. Wait and read.
• Large, clear catalyst (15 or more points). Default lean is continuation, because the news may be real information. I still wait out the opening noise.
• Exhaustion gap. A gap beyond the extreme of a multi-day trend. Be careful with either side here.

I'm not quoting fill percentages. Those depend on the period, the instrument and how you define a fill, and anything I could cite here would not be verified.

Features that lean toward a fill

• Small size relative to recent daily range and no identifiable catalyst
• An open sitting at the overnight high (for gaps up) or low (for gaps down)
• A first 5-minute bar that closes against the gap
• Light overnight participation
• A gap against the larger trend

Features that lean toward continuation

• Large size with a scheduled or obvious catalyst
• Heavy overnight volume during the move
• An opening range that holds above the prior close (for gaps up) or below it (for gaps down)
• An open that still leaves room before the overnight extreme
• A gap in the direction of the daily trend

The 15-minute rule

Watch the first 15 minutes, 9:30 to 9:45 AM ET, with no orders. Then read what happened:

1. Opening range entirely beyond the prior close and dips are bought: the gap is being defended, so lean toward continuation.
2. Prior close sits inside the opening range: unclear, trade smaller or stay out.
3. First bars sell hard into the gap and the range breaks back toward the prior close: lean toward a fill.

The cost of this rule is real. You'll miss part of some moves, and some range breaks will fail. In exchange, you avoid acting in the noisiest minutes of the day.

Entry mechanics with worked numbers

For a fill setup after a gap up, wait for a break below the opening range low and place the stop above the range high. Hypothetically, if the opening range is 8 points wide, that stop is about 8 points away: $400 per ES contract or $40 per MES. The target is the prior close. If the prior close is 20 points below the entry, that is 20 points of potential reward, $1,000 per ES contract, against $400 risked, or 2.5 to 1 before fees and slippage. Whether the market delivers it is a different question.

For a continuation setup, buy a break above the opening range high with a stop below the range low. Same arithmetic: the width of the range is your risk, so a wide range means fewer contracts. If the width forces a stop larger than your daily loss limit allows, skip the trade. That is a legitimate result of the rule.

YMI's KPL are fixed reference prices anchored to the RTH opening print, so on a gap morning they can't be completed before the open. After the open, they can show where a gap fade or a gap continuation runs into a reference price. You can see how the levels are built on the KPL trading page.

Common errors

Fading a large news-driven gap because it looks extended. Chasing a small gap because it feels like momentum. Trading in the first five minutes, when spreads, fills and direction are least reliable.

How to test it yourself

Log every gap morning for several months with size, catalyst, opening range result, whether you traded, and what happened. Review the table before you change thresholds. A couple of dozen gap days won't prove a rule, and a rule that worked for one volatility regime can stop working in another. Simulated results also overstate fills near the open.