A limit order allows you to guarantee that, if a trade is possible, you will receive a specified price (limit price) or better. However, if there is too much movement in the market, or the stock never reaches or surpasses the limit price, a trade will not be executed. Thus, a limit order guarantees a price or better, but not an execution.
These types of orders also may be placed with special instructions, like AON (All or None) and GTC (Good til Canceled) and GTD (Good til Date).
AON - An AON order will only be executed if all shares requested can be purchased in one lot at the specified limit price. AON is a restriction or limitation to a limit order.
GTC - A GTC order will remain active until it is filled, cancelled by you, or no action has been taken by the last day of the month following the month of order entry. For example, a GTC order placed on March 15 will expire on April 30 at Scottrade.
GTD - A GTD order will remain active until a specified date and a specified time chosen by you.
Day Order - A day order will expire at the end of the trading day, if it's not executed before market close.
Any order submitted outside of market hours for regular session trading will queue until the next business day.
There are two types of limit orders: buy and sell.
Buy Limit Orders - Orders will execute only if the market reaches the specified price or lower for a long enough period of time to execute the order.
Sell Limit Orders - Orders will execute only if the market reaches the specified price or higher for a long enough period of time to execute the order.
For listed (NYSE, NYSE Amex) and NASDAQ stocks and all OTC securities:
Limit prices may include up to two decimal places for stocks above $1.00
Limit prices may include up to four decimal places for stocks under $1.00