A cancellation request can cross a fill message while an execution system is preparing a replacement. If the replacement assumes the old order has disappeared, one desired purchase can become two. Live monitoring protects the intended portfolio by checking positions, outstanding orders and the reliability of the information used to control them. Building on the order lifecycle and post-trade reconciliation, this lesson develops quantity invariants, operational alerts and a disciplined restart process.
Learning objectives. By the end of this note you should be able to:
- compute worst-case additional exposure from working and uncertain orders;
- explain why cancellation requests and timeouts do not release quantity reservations;
- separate data, execution, exposure and performance monitoring;
- define an alert that leads to a specific operational response;
- reconstruct a cancellation race and identify the conditions for safe resumption.
In this lesson
- Observe what is held and what can still fill
- A cancellation race, event by event
- Portfolio checks must include opposing orders
- Four monitoring views and their actions
- Write alert rules as decisions
- Stop, reconcile and resume
Before you start
The full lesson, with worked examples and exercise solutions, is for members.
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