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Risk management

Kill switch

By Jarosław Wasiński • Published: • Updated:
A predefined procedure for suspending trading or restricting further activity when a specified threshold or operational fault is detected. Triggers can include daily P&L, drawdown, consecutive losses, faulty data or failures. Specify the measure, condition, treatment of new orders and open positions, and restart rules. Its purpose is to limit further exposure and procedural breaches, not guarantee an exit price or eliminate losses. Regulatory algorithmic-trading “kill functionality” has a separate, specific legal scope.
Example.

A hypothetical plan starts the day at USD 10,000 equity, uses a fixed R of USD 100 and sets a net daily P&L limit of −3R, or −USD 300, with no deposits or withdrawals. Equity of USD 9,700 triggers a pause. The plan specifies a block on new entries, cancellation of pending entry orders and treatment of open positions. Three losses are not required: one loss with slippage could hit the limit. A higher interim result does not change the agreed USD 10,000 reference.

Trigger, action and restart

Specify the measured quantity, threshold, monitoring times, response and conditions for restarting. Establish whether daily P&L includes open positions and costs, when the trading day begins, and how deposits are handled. Disabling new entries does not automatically liquidate every position. Both actions can be required but need separate instructions. Restarting after a review and confirmation of operational readiness is different from automatically resuming the next day.

More than a financial loss limit

Trading can also stop because of faulty data, lost connectivity, position discrepancies or procedural breaches. Thresholds require evaluation rather than a universal two- or three-loss rule. In EU requirements for algorithmic-trading investment firms, “kill functionality” means emergency cancellation of unexecuted orders. A personal kill switch may prescribe broader actions, but its account-loss limit should not be confused with that specific legal requirement.

Test the response, not just the alert

In simulation, check whether every order-entry channel is blocked, cancellations are acknowledged and remaining exposure has a designated manager. Record confirmations, account state and the triggering reason. An easily ignored alert differs from a technical block. Neither guarantees a loss stopping exactly at the threshold: gaps, latency or failures can cause an overshoot. The purpose is a defined response and reduced further exposure, not a promise of no drawdown.

Further learning and sources

9.8 Drawdown: two definitions and the procedure for halting trading; 9.11 Risk management plan – a template to fill in and a pre-trade checklist; 11.5 Trading automation: EAs, MQL scripts, cBots and VPS.

Primary sources (checked 2026-10-11): Delegated Regulation (EU) 2017/589, Article 12.

FAQ

Must a kill switch close every position?
Not by definition. The plan must separately specify order cancellation, entry blocking and management of positions already open.
Is −3R suitable for every strategy?
No. It is an illustration. Evaluate the threshold and procedure against outcomes, risk tolerance, costs and account constraints.

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Jarosław Wasiński

Editor-in-chief, ForexMechanics.com • Macro & FX analyst

Independent analyst and practitioner with over 20 years of experience in financial markets. Actively involved in Forex since 2007, with a focus on fundamental analysis, OTC market structure, and disciplined capital risk management.

  • Creator and editor-in-chief of MyBank.pl, providing reliable financial education since 2004.
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All content is educational and informational only – it does not constitute investment advice or a recommendation. Remember: leveraged trading (Forex/CFD) carries a high risk of rapid capital loss.