When the activation level of a stop order is reached, a market order is triggered. Although all orders are executed at extremely high speeds, the execution price may differ from the activation level. This is called slippage.
Slippage may occur in fast moving markets. For example, when important economic data is published or when important and/or unexpected events occur. Market participants will remove their working orders from the market leading to nearly empty order books.
Market participants who keep their orders working, will often put them at more conservative price levels, leading to the widening of the market spread.
In fast moving markets the market price moves intermittently, i.e. there is not an execution on every price level. We advise you to read with attention the risk notice, which is part of your account application.