Gap Trading: Simple But Requires Precision

Gap trading is straightforward: Price gaps open above or below the previous close. You bet it will either fill (revert) or continue. But execution details matter significantly.

Advantage: Gaps are objective. Either there’s a gap or there isn’t. The fill level is also objective. This clarity removes opinion.

Disadvantage: Gaps don’t always fill. And when they don’t, you’re fighting the trend direction. Gap fade trades have lower accuracy than trend continuation trades.

Gap Statistics

Research on forex gaps (4-hour+ candles):

Gap Size	Fill Probability	Avg Time to Fill	Continuation %
5-10 pips	85%	1-4 hours	15%
10-20 pips	75%	2-8 hours	25%
20-30 pips	65%	4-12 hours	35%
30+ pips	55%	12+ hours	45%

Implication: Small gaps have high fill probability and fast fill time. Large gaps have low fill probability and might represent real trend starts.

Strategic insight: Gap trading works best on small gaps (5-20 pips). Large gaps are often trend starts, not reversions.

Types of Gaps

Overnight Gaps (most common in forex)

Market closes at 5pm EST (New York close). Reopens at 5pm Sunday EST (Sydney open). News/geopolitical events or Asian session moves can create gaps.

Probability: Small overnight gaps (5-15 pips) fill quickly within the Monday Asian/London session. Large gaps often persist and represent real moves.

Weekend Gaps

Friday close to Monday open. This gap can be larger because it spans 2+ days of thinking/news. Weekend gaps are more likely to represent real trend starts than overnight gaps.

Low-Liquidity Gaps

Gaps that occur during low-volume sessions (e.g., US market holidays when only forex traders are active, Asian pair gaps during NY close). These gaps tend to fill because liquidity is thin.

News Gaps

Sharp gaps immediately after major data release (NFP, GDP, etc.). These gaps often don’t fill because they represent new information, not technical reversion.

Gap Fill vs. Gap Continuation Edge

Strategy 1: Play the Fill (Fade the Gap)

Gap up 25 pips → Short it, targeting the previous close

Probability: 75% fill on 25-pip gaps Average R if gap fills: 1.3R (25 pips risk, 25 pips reward for fill, but could hit 2:1 if you wait) Risk: Gap continues instead of filling. You get stopped out and miss the real move.

Expected Value: (0.75 × 1.3R) - (0.25 × 1.0R) = 0.975R - 0.25R = +0.725R positive expectancy

This is a viable edge if you execute it properly.

Strategy 2: Play the Continuation (Trade the Gap Direction)

Gap up 25 pips → Buy the gap, betting it continues higher

Probability: 25% continuation on 25-pip gaps Average R if gap continues: 1.8R (25 pips risk, 45 pips profit average) Risk: Gap fills instead. You get stopped out.

Expected Value: (0.25 × 1.8R) - (0.75 × 1.0R) = 0.45R - 0.75R = -0.30R negative expectancy

Gap continuation is a losing trade for small-medium gaps. Only viable on very large gaps (30+ pips) where fill probability drops below 50%.

Conclusion: For most gaps, trading the fill (fade) has better edge than trading the continuation.

Tracking Your Gap Edge

After 30 gap trades, calculate:

Fill Trades (shorting up gaps, buying down gaps):

• of fill trades taken: 20

• that filled: 15

• Fill rate: 75%
• Average R per fill: 1.4R
• Expectancy: (0.75 × 1.4R) - (0.25 × 1.0R) = +0.60R

Continuation Trades (buying up gaps, shorting down gaps):

• of continuation trades: 10

• that continued: 2

• Continuation rate: 20%
• Average R per continuation: 2.1R
• Expectancy: (0.20 × 2.1R) - (0.80 × 1.0R) = -0.38R

Finding: Fill trades are profitable; continuation trades lose. Stop taking continuation trades. Focus only on fades.

Weekly Gap Review

Every Monday (or after a trading session with gaps):

1. Gap identification accuracy

Did you spot all gaps? Or did you miss some because you were focused on other trades? Consistency matters.

2. Fill rate

Of the 5 gaps that opened, how many filled? Track the exact fill time (within 30 min, 1-4 hours, 4+ hours).

3. Trade selection

Which gaps did you trade? Did you trade the small 8-pip gaps or the large 45-pip gaps? Review if your gap selection matches your edge.

4. Entry timing

For gaps you traded, when did you enter? Immediately at open? After a small retracement? Entry timing affects your win rate. Small retracement + confirmation usually has better accuracy.

5. Outcome vs. expectation

Did gaps behave as expected (small gaps filled, large gaps didn’t)? Or was there unusual continuation on a small gap? This reveals when gap trading breaks.

Common Gap Trading Mistakes

Mistake 1: Shorting every up gap

You assume every up gap will fill. But 45-pip gaps on strong news often don’t. You keep shorting large gaps and getting stopped out.

Fix: Only trade small-medium gaps (5-25 pips). Skip gaps larger than 30 pips or trade them differently (play continuation instead).

Mistake 2: Entering immediately without confirmation

Gap up 20 pips. You short immediately. But price continues up another 40 pips before reversing. You were right about the fill but got stopped out first.

Fix: Wait 30-60 minutes for a small pullback/confirmation. Enter on a candle pattern that confirms the gap will fill. This improves accuracy.

Mistake 3: Trading low-volatility, low-pip gaps

Gap 5 pips on a quiet Asian session. You short it, targeting the 5-pip fill. Even if it fills, you made 5 pips. Low pips per hour. Not worth the trade.

Fix: Only trade gaps above 10 pips. Small gaps fill too slowly to be profitable.

Mistake 4: Not accounting for the time it takes to fill

Gap 20 pips. You expect fill within 1 hour. But fill takes 6 hours, and you have overnight exposure. You get nervous and exit early, missing the fill.

Fix: Accept that fills can take multiple hours. Use time-based exits (hold for 4 hours, then exit) or wait for the actual fill level.

Mistake 5: Oversizing on gaps

Gaps feel high-probability, so you size up to 1.0 lots instead of 0.25. Gap doesn’t fill (it was a 40-pip gap, outside your criteria). Large loss hurts.

Fix: Use normal position sizing (1-2% risk). Gaps aren’t more certain than other trades.

Building a Gap Trading Edge

After 100 gap observations and 50 gap trades:

“I’ve tracked 100 gaps. Small gaps (5-20 pips) fill 77% of the time, average R 1.5R. That’s +0.425R positive expectancy. Medium gaps (20-30 pips) fill 68% of the time, average R 1.2R. That’s +0.216R. Large gaps (30+ pips) fill 52% of the time, average R 0.8R. That’s -0.04R (breakeven). My edge is in small-medium gaps. My rule: Only trade gaps 10-25 pips. Wait for 30-min pullback confirmation before entering. Play the fill (fade). Skip gaps larger than 30 pips.”

This is professional gap trading: measure everything, specialize in what works.

The Bottom Line

Gap trading is viable but only in specific conditions:

1. Trade small-medium gaps (10-25 pips) — These have high fill probability
2. Play the fill (fade) — Gap continuation has poor odds
3. Wait for confirmation — A 30-min pullback + candle pattern before entering
4. Use time limits — Hold for 4-6 hours max; if gap doesn’t fill, exit
5. Track religiously — Your gap trading edge exists only in certain gap sizes and market conditions

Many traders find gap trading more trouble than it’s worth. If your data shows positive edge, it can be a nice complement to other strategies. If your data shows breakeven or negative, abandon it and focus on setups where you have clear edge.

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PipJournal tracks every gap, logging size, direction, and whether it filled. After 30 gaps, you’ll see exactly which gap sizes and conditions have your edge, so you can focus on high-probability gap fill trades.