A weekend gap is the difference between Friday's close and Monday's open, created because currency markets stop trading while news does not.
Stops do not protect you across it. A stop-loss is an instruction to sell at the next available price, and if the market opens beyond your level, that is where you are filled — the loss can exceed what the position size implied. Guaranteed stops, where offered, close that hole for a fee. The practical defences are smaller size into the weekend, no leverage-heavy positions held over political events, and checking the Sunday open before your Monday plan assumes Friday's chart is still valid.
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Guide
What Happens to Your Trades Over a Weekend
Between the Friday close and the Sunday open there is no price, no execution and no way out. What that means for stops, gaps, weekend financing and the size you decide to carry.