A market order lets you buy or sell a security at the price currently available in the marketplace. When you place an order during normal market hours (9:30 AM to 4:00 PM ET), a market order typically executes within seconds. When you place a market order during non-market hours, we'll enter it when the market opens, so it executes as soon as possible. When you place a market order you are not guaranteed that the order will execute at any specific price.
Tip: You may see a short delay between the time you complete your trade and the time your holdings update within your ShareBuilder account.