OCO Order

An OCO (Order Cancels Order) order consists of a group of two or more parallel orders that are linked together in such a way that if one of the orders is filled, then all of the other parallel orders are canceled.

For example, let say that an OCO order consists two orders; 1) a limit order to buy 500 shares of one symbol and 2) a stop order to sell 200 share of another symbol.  If the limit price of #1 is hit and fills, the stop order #2 is automatically canceled.  

There is no limit to the number of parallel orders in an OCO group of orders. When any one of them is filled, the others in the group are canceled.