One Cancels the Other (OCO)

OCO is the one order in this unit that ties two separate orders together. The trap is simple once you see it: a fill on either leg cancels the other leg, automatically. That is the whole idea, so anchor on it.

What an OCO Order Is

An OCO order links two orders so that only one of them can ever execute.

• One cancels the other (OCO) order: two orders entered together and linked, so that when one order is executed (filled), the other is automatically canceled.
• The legs are contingent on each other: only one can ultimately execute. The fill on the first leg triggers immediate cancellation of the second, with no manual action from the trader.
• Either leg can be the one that fills: the pair does not care which side goes first. Whichever leg trades, the other is pulled automatically the moment it does.

The Common Bracketing Use

The reason OCO exists in a trader's toolkit is to bracket a position with two opposite exits at once.

• Bracket a position: OCO is typically used to place a profit-target limit order on one side and a protective stop order on the other, so the position has both an upside exit and a downside exit resting at the same time.
• The classic long example: a long futures holder places a sell limit above the market (to take profit) and a sell stop below the market (to cap the loss) as an OCO pair. Whichever triggers first fills, and the other is canceled automatically, so the trader is never left holding a stray resting order after the position closes.
• No manual cleanup: because the cancellation is automatic, the trader does not have to remember to pull the second order once the position is closed. The pair handles it.

Think of it this way: an OCO pair is like setting two alarms for the same event, one on your phone and one on your clock, wired so that silencing either one shuts off both. You do not have to run around turning off the second alarm once the first has done its job. In trading terms, your profit target and your stop-loss both sit ready; the instant one fires and closes the position, the other stands down on its own.

Exam Tip: Gotchas

• A fill on either leg cancels the other, automatically. Only one order in an OCO pair can ever execute. If a choice says the trader must manually cancel the second order after the first fills, it is wrong, the exchange or platform does it for them.
• The classic bracket is a sell limit above and a sell stop below on a long. The limit takes profit as the price rises; the stop caps the loss as the price falls. Do not flip the placement: the profit-target limit sits above the market and the protective stop sits below it.

Order Comparison

Here are all four qualifiers from this unit in one place, with the trap each one carries: good till canceled (GTC), fill-or-kill (FOK), market on close (MOC), and one cancels the other (OCO).