Module 6 · Lesson 13 of 17 · Risk, process, and mindset · About 5 minutes
Overnight and Gap Risk: When Prices Jump Past a Stop
On this page
Before you read: Risk Management Arithmetic: Position Size, Risk-Reward, Drawdown
What you will learn
- What gap risk is and why it exists when markets are closed or thin.
- Why a stop order does not cap a loss at the stop price.
- How weekends, scheduled news and holidays affect positions held overnight, in general terms.
What is a gap?
If a stock closes at $50 and opens at $44, what happened to every price in between?
A gap occurs when the next traded price is far from the last one, with no trades in between. Stocks can gap between the close and the next open because news arrives while the main session is closed. Futures trade nearly around the clock but can still gap over weekends, after a daily break, or within seconds when news hits a thin order book.
Why does a stop not cap the loss?
If a stop sits at $48 and the open is $44, where does it fill?
A stop order becomes a market order once its price is reached. If price opens below the stop, the order fills at the next available price, here near $44, not $48. In a fictional position of 100 shares with a planned loss of $200 to the stop, the actual loss would be about $600 plus costs. A stop-limit order avoids that fill price but may not fill at all.
Gap diagram
Illustrative diagram constructed for teaching. Not real market data.
The diagram shows fictional candles closing at $50, a dashed stop line at $48 and the next candle opening at $44. Brackets compare the planned loss to the stop with the actual loss to the open. All values are made up.
Which situations raise gap risk?
Which calendar dates bring more uncertainty to an overnight position?
Company earnings, economic reports released before the open, central bank decisions, weekends, holidays with closed markets and broad news events all raise the chance of large gaps. Leverage makes a gap’s effect on the account larger. Brokers can raise their own margin requirements during volatile periods, sometimes with little notice.
What this does not tell you about gaps
- When or how far any market will gap.
- Whether holding positions overnight suits anyone.
- Real fill prices, which depend on the order book at the time.
- Nothing here suggests any trade.
Method in Practice: holding over a close
Fictional example. John, Harbor Index futures, the prices, times, costs and results are all invented for teaching. This shows how a written plan can be built and tested. It is not a recommendation, and nothing here says how often this idea works.
Try it on a real chart. Test this idea yourself on past sessions with bar replay. Keep your own count, including the days with no trade.
The idea. A stop order becomes a market order when it's reached. If price opens past it, it fills at the next available price (this lesson). John's day plan never holds overnight. Here he tests a written variant that sometimes does, to see what a gap does to it.
John's overnight variant
- Same entry rule as Volume Profile Explained: POC, Value Area, HVN, LVN. Half at 101.80 as usual
- Hold the rest overnight only if: at 14:30 it's at least 0.50 above entry, it's Monday to Thursday, and no major release is due before the next open
- Overnight stop: 101.60, just above the entry (stop order)
- Next day: sell the rest at 102.80 (limit), or at market by 10:00
Three outcomes
-
Held, no gap problem: the rest sold at 102.80 next morning → +$150
-
Gap through the stop: opened at 100.70, below the 101.60 stop. Filled at 100.65 → −$65 on a trade whose stop was above entry
-
Didn't hold: it was Friday, so the time limit closed it → +$70
Show the full replays
Entry for all three: the Volume Profile Explained: POC, Value Area, HVN, LVN lesson's rule. The second close above was 101.45, so the market order filled at 101.50 (one tick worse). Bought 2. Half sold at 101.80 (limit).
| Replay | 14:30 check | Overnight | Next day | Result after costs |
|---|---|---|---|---|
| A, held | Price 102.20, 0.70 above entry. Tuesday, no release | Stop at 101.60 | Opens 102.40, trades 102.80 at 09:20. Sells at 102.80 (limit) | +0.30 = +$30, +1.30 = +$130, −$10 = +$150 |
| B, gap | Price 102.05. Wednesday, no release | Stop at 101.60 | Opens 100.70 after overnight news. Stop fills at 100.65 | +0.30 = +$30, −0.85 = −$85, −$10 = −$65 |
| C, Friday | Price 102.05. Friday: no hold | — | Sells at market at 14:30, filled 102.00 | +0.30 = +$30, +0.50 = +$50, −$10 = +$70 |
Journal, Replay B: "My stop was above my entry, and the held contract still lost $85. The stop was a plan for the price, not a promise about the fill."
Test it yourself
- Find the largest overnight gaps in your test period, and replay your stops through them.
- Size overnight positions for the gap, not the stop distance.
- Count the Fridays and release nights your rules skip.
Where it breaks
- A stop doesn't cap a loss when price opens past it (the failed replay).
- Weekends, holidays and releases make gaps more likely (this lesson).
- Futures trade nearly around the clock but still close daily and on weekends.
Reflection question: If your market opened beyond your stop tomorrow, how big could the loss be?
Check yourself
- Why can a stop order fill well past its price? Hint: what does it become?
- In the fictional example, why is the loss about $600 rather than $200? Hint: the open price.
- Name three scheduled events that can cause gaps. Hint: company, economy, calendar.
Reflect on your own process
- What does your written plan say about holding positions over weekends, holidays or scheduled reports, and why?
- How does your plan size a position if the loss could be larger than the stop distance suggests?
- Where does your journal record cases where a fill landed past your stop, and what did you note?
- If your market opened beyond your stop tomorrow, how big could the loss be?