Glossary
Circuit Breaker ACOS
A Circuit Breaker ACOS is a hard emergency threshold that pauses or restricts automated ad changes when a campaign's ACOS crosses it. Unlike a target ACOS, which is a goal the optimizer steers toward, a circuit breaker is a kill switch that stops the automation from compounding losses when performance goes off the rails.
Why it matters for Amazon sellers
Every AI or rule-based PPC system carries the same latent risk: a bad cycle runs, the system misreads the signal, and it scales spend into something that was never going to convert. A circuit breaker is the structural defense against that scenario. When ACOS for a campaign, ad group, or keyword exceeds the circuit-breaker threshold, the system reduces authority: it may pause auto-execution, force changes through approval, drop back to review-only mode, or stop budget increases entirely. Circuit breakers work best in combination with other bounded controls: max bid limits, daily budget change caps, and spend-increase ceilings. Together, those controls keep an AI agent inside a cone of acceptable behavior even when a single signal is wrong. A good PPC platform exposes the circuit-breaker ACOS as an explicit setting so operators can tune it to their risk tolerance instead of trusting an opaque default.
How Profasee handles this
Marko's safety settings include an explicit circuit-breaker ACOS alongside max bid, daily bid change limit, daily budget change limit, and daily and weekly spend-increase limits. When a campaign crosses the circuit breaker, Marko stops further increases, routes new changes to approval, and flags the situation in the operator's daily review. The rest of the account keeps operating inside its own guardrails.
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Frequently asked questions
What is a circuit breaker ACOS?
A circuit breaker ACOS is an emergency threshold that halts or restricts automated ad changes when performance degrades past a set limit. It is a hard stop, not a soft goal. Unlike a target ACOS, which the optimizer tries to reach, a circuit breaker takes the AI's hand off the wheel when things go wrong.
Why do I need a circuit breaker if I already set a target ACOS?
Because targets and limits do different jobs. A target tells the system where to aim. A circuit breaker stops the system from making things worse when the aim is off. Even well-tuned automation can misread a signal. The circuit breaker bounds the damage while the operator investigates.
How do I choose a circuit-breaker ACOS level?
Set it above your target ACOS but below the point where the campaign becomes clearly unprofitable given your margins. For a product with 40% contribution margin and a 25% target ACOS, a circuit breaker around 45 to 55% gives the optimizer room to adjust without letting a bad cycle compound.
Related terms
ACoS (Advertising Cost of Sales)
ACoS (Advertising Cost of Sales) is the ratio of advertising spend to advertising-attributed revenue...
Read the ACoS (Advertising Cost of Sales)definition →
AI Guardrails
AI guardrails are hard boundaries on what an AI system is allowed to do — spending limits, price flo...
Read the AI Guardrailsdefinition →
Operational Readiness
Operational Readiness is the state that tells an AI agent whether it can actually act. It is not the...
Read the Operational Readinessdefinition →
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