The purpose of a market order is to execute regardless of market movement. The rate displayed in the market order placement form is an estimated rate and not the actual execution rate.

For a fixed execution rate, you have the options of limit, stop loss or FOK orders.

The difference between the displayed price and the execution price of an order is called slippage. Between the moment an order is placed on the platform and its execution on the market, there may be a very small time difference during which the exchange rate may vary