In trading, a market-on-close (MOC) order instructs a broker to buy or sell specific securities on behalf of an investor at the closing rate when trading hours end.
Unlike a limit-on-close (LOC) order, an MOC order does not include a limit on the price at which a security should be sold. Instead, it is a market order which instructs a broker to sell the securities at the best available bids at the time that the market closes.
Example: An investor want to sell their shares in a company as soon as the market closes because they believe the price of the shares will climb by the end of the trading day and they want to avoid incurring overnight fees. They place an MOC order with their broker to sell their shares when the market closes for the day at the best bid offered by buyers at the time.
See also: Market-on-open order