When you place an order, you’re telling us how to trade a security on your behalf. There are four types of orders you can make within a Wealthsimple trading account:

• A market buy order (default)
  Buy or sell a stock immediately at the best available price. 
• A fractional buy order
  Buy or sell a fraction of a share for certain stocks. Your order will be executed at the end of the trading day or the next available trading day.
• A limit buy order
  Choose a maximum price you're willing to buy or sell a stock for.
• A stop-limit buy order
  Choose a stop price and a limit price. Once a stock hits the stop price, your order will get converted to a limit order. People often use stop limit orders to try and limit losses or protect gains.