A stop order becomes a market order once the price reaches a specified trigger level, typically used to enter a breakout trade (a buy stop placed above resistance) or to exit a losing position (as in a stop-loss). Because it converts to a market order on trigger, it can suffer slippage in fast conditions, just like any other market order.
This is distinct from a limit order: a stop order is placed anticipating the price will continue in the same direction once it reaches the trigger, while a limit order anticipates a reversal at that level.
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Margin Calls and Stop-Outs Explained
Balance, equity and margin level explained — how a margin call differs from a stop-out, which position closes first, and when a gap outruns the system.