In plain English
What One cancels the other means
OCO is commonly used to place alternative exit instructions for the same position: for example, a take-profit limit order above the market and a protective stop order below it. The intention is that one outcome closes the position and makes the other instruction unnecessary. However, OCO is an automation feature, not a guarantee that every linked order will be canceled before another can execute during rapid price moves or system delays.
Why it matters
Without linked cancellation, two independent exit orders can both remain live after one executes, potentially opening an unintended new position. OCO reduces that operational risk, but users still need to understand the platform’s handling of partial fills, rejected orders, connectivity failures, and cancellation timing. In OTC forex and CFDs, the feature may be implemented on the broker’s own server rather than on an exchange.
Example
A trader is long 10,000 units of EUR/USD from 1.0800. They create an OCO pair: a sell limit at 1.0900 and a sell stop at 1.0750. If the 1.0900 limit order fills in full, the platform should cancel the 1.0750 stop. This example is simplified; partial-fill and cancellation rules vary by platform.
Quick answers
Common questions
Is OCO the same as a bracket order?+
Not exactly. OCO links alternative orders so one execution cancels the other. A bracket order usually combines an entry order with attached profit-taking and protective exit orders, often using OCO logic for the exits after the entry fills.
What happens if one OCO order is partially filled?+
That depends on the implementation. Some systems leave the linked order unchanged until a full fill; others reduce linked quantities or use overfill controls. Review the platform’s specific OCO rules before relying on the feature.
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