Designing circuit breakers for trading automation

A circuit breaker changes automation into a restricted state when an observed condition crosses a configured boundary. Useful triggers include stale market data, repeated exchange errors, reconciliation mismatches, unexpected position growth and loss limits. The breaker can prevent new requests, but it cannot undo an accepted order or guarantee that an open position closes.

Separate entry from exit actions

A blanket shutdown may block the very action needed to reduce exposure. Define whether each trigger rejects new entries, permits reduce-only actions, cancels resting orders or stops all exchange communication. Default to preventing additional exposure, then require an explicit and auditable decision for actions that could increase it.

Use signals that can be verified

Every trigger needs a data source, threshold, evaluation window and reason code. Combine related observations carefully: one network timeout may be transient, while repeated timeouts plus an unknown order state require caution. Monitor whether the detector itself is alive so a silent worker or frozen data feed cannot appear healthy.

Recovery is a controlled transition

Do not resume merely because a timer elapsed. Verify current orders, positions, balances, data freshness and credentials at the exchange. Record who acknowledged the alert, what evidence was checked and which settings changed. Restart with limited scope and observe a complete cycle before restoring ordinary operation.

Operational takeaways

• Document which actions remain available for every breaker state.
• Use reason codes and alerts that identify the account, bot and triggering evidence.
• Test stale-data, error-burst and reconciliation triggers without real funds.
• Require exchange-side verification and an accountable acknowledgement before recovery.
• Keep a manual way to manage the account when the platform is unavailable.

Circuit breakers limit programmed behaviour under defined observations. They do not guarantee a loss ceiling, availability, execution quality or profit, and passing their checks is not advice, certification or regulatory approval to trade.