Stop-loss slippage vs gaps: why your stop can fill worse than planned

A stop-loss is an instruction, not a guarantee. When price reaches your level, a standard stop becomes a market order and fills at the next available price. Most of the time that is your level or very close to it. Sometimes it isn't, and knowing when that happens is part of controlling risk.

Slippage and gaps: two different problems

	Slippage	Gap
What happens	Price moves fast and the fill comes a few pips past your stop	Price jumps over your level without trading in between
When	Around major releases, at thin hours	Market reopening, weekend news, earnings for shares
Typical size	A few pips on major pairs, more on gold and indices	From small to very large

When it is most likely, in Paris time

• Major US data, such as the monthly employment report, usually at 14:30 Paris time (it can shift by an hour when the US and Europe change clocks on different dates).
• Central bank decisions and their press conferences.
• The weekly reopening of currency markets late on Sunday evening, Paris time, after weekend news.
• The quiet hour around the daily rollover, when spreads widen.

The market sessions tool shows which markets are open at any time, converted to your clock.

A worked example

You plan to risk $100 on EUR/USD with a 25-pip stop.

	Value
Size from the stop	$100 ÷ (25 pips × $10 per pip per lot) = 0.4 lot
Pip value at 0.4 lot	$4
Slippage of 5 pips at the stop	30 pips × $4 = $120 loss
Gap of 40 pips over the weekend	65 pips × $4 = $260 loss

Illustrative calculation, not an expectation of results.

Run your own numbers with the lot size calculator and the pip value calculator.

Five ways to limit the damage

1. Leave a margin in your risk budget. If your rule is 1% per trade, plan the size so that a few pips of slippage still keep you near 1%.
2. Avoid holding through scheduled releases if your plan doesn't require it.
3. Decide a weekend rule: close, reduce, or hold with a size that survives a gap.
4. Know your firm's order types. Some authorised firms offer guaranteed stops for a fee; check the terms on the firm's own site.
5. Remember negative balance protection applies to retail clients of EU-authorised firms (retail protections explained); it limits the worst case, not the ordinary one.

The point

Slippage is not a reason to trade without a stop; it is a reason to size smaller and to think about when you are exposed. A stop you moved further away is a bigger problem than a stop that slipped (why traders move their stop). Most retail traders lose money, and unplanned gaps are one of the ways it happens.