Where a stop order actually fills when price gaps through it

[Fairman]

Where a stop order actually fills when price gaps through it

A stop loss is a stop order, and a stop order becomes a market order when it's triggered. That's fine on a normal tick by tick market. When price gaps through the stop, the fill comes at the next available price, which can be well beyond the level you set.

The obvious time this happens is the Sunday open. A stop sitting at a level that price jumps over gets filled at the first quote after the open. But it also happens intraday on big releases, where the market can skip several pips in a single tick.

A few broker details change how bad it is:

Some brokers fill at the first price on the other side of the gap. Others may fill at a worse price if liquidity is thin at that first tick. Read the execution policy for what they say about gapping and slippage on stops.

Guaranteed stop orders exist at some brokers, usually for a fee or a wider spread. They promise the fill at your level regardless of gaps. For a scalper they're rarely cheap enough, but find out whether your broker offers them anyway.

Server side versus client side stops matter too. A stop that lives on the broker's server is executed even if your terminal is closed. Some platforms or EAs manage stops locally, and a gap combined with a slow connection can make the fill much worse.

None of this means avoiding stops. It means understanding that the stop level is the trigger, not a guaranteed exit price, and sizing with that in mind on days where gaps are more likely.

Separate stops hit by price from stops hit by spread, too. On a gap the two get mixed up, since the spread is often wide on the first quote, and a sell stop can trigger on a bid that's well below where any real trading happened.

[FXS London Scalper]

Stop orders turning into market orders on a gap is the key point. Around news it is worth knowing that spreads widen just before the gap, so a stop can be triggered by the ask or bid moving even if the mid price has not reached the level yet. For London traders this happens most often at 07:00 on UK data days and at 13:30 for US releases. Guaranteed stops avoid the gap at a cost, but simply being flat or having reduced size at those times is cheaper for most scalpers.

[Fairman]

Go back through your own trade history and look at fills on stops versus the stop level you set. Most platforms record both. If the difference is consistently small except on a few release days, that's normal. If there's a steady extra slip even on quiet days, the problem is probably the broker's execution rather than gaps, and that's a separate conversation with them. Having actual numbers from your own account is much more useful when raising it with support than a general complaint that stops feel like they slip.

[Fairman]

Positive slippage on stops is rare but does happen at some brokers. If the market gaps in your favour while a stop is pending, some execution models will fill at the better price and some will fill at your stop level and keep the difference. That asymmetry, where you get the worse price but never the better one, is something regulators in some regions have looked at. Checking whether your fills ever show positive slippage is a simple way to see which kind of execution model you're dealing with. It's a quick filter in the trade history to look at only stop exits and compare the fill prices.

[Fairman]

Limit orders behave differently in a gap. A take profit is usually a limit order, and when price gaps through it, many brokers fill at the better price that actually traded, or at your level if that's their policy. So a gap can hurt your stops and leave your targets only filled at the exact level. That's another case of the asymmetry between stop and limit orders that scalpers often don't think about until it shows up in their trade history. So when reviewing results around news, look at targets and stops separately. A strategy whose targets get filled exactly but whose stops slip on gaps has a hidden cost that the average win and average loss figures don't fully show unless you split them.

[Fairman]

For anyone holding over a weekend, a common way to limit gap risk is simply to hold smaller or not at all. A scalper rarely needs to be in the market at the Sunday open. If your style does occasionally hold positions into Friday's close, setting a rule like closing everything by a fixed time on Friday takes the decision out of your hands and avoids the gap question entirely for most trades. Friday afternoon liquidity also thins out, so even closing before the weekend can cost more spread than the same exit midweek. Closing a little earlier than the final hour avoids most of that, and it means you're not trying to exit at the same moment as everyone else who had the same plan.