Sarah Breeden, the Bank of England’s Deputy Governor for Financial Stability, said humans face significant difficulty supervising autonomous artificial intelligence in real time and that existing financial regulations may not adequately address agentic AI. Speaking at the European Central Bank’s annual forum in Sintra, Portugal, on June 30, she proposed market-wide circuit breakers and kill switches that could halt trading if an AI-driven cascade spirals out of control. Breeden also called for stronger recovery protocols allowing one bank to assume another institution’s essential functions during an AI-related crisis and urged regulators to assess and adjust oversight mechanisms swiftly. Her warning comes as a Cambridge Centre for Alternative Finance survey found that roughly 52% of financial firms were deploying agentic AI by mid-2026. She cited risks including correlated trading strategies, systemic cyber threats, amplified shocks, unresolved questions over consent and liability, and new operational exposure for firms dependent on uninterrupted market access. The Bank of England has been working with the Financial Conduct Authority and a public-private AI Consortium on financial-system resilience, while Breeden’s remarks marked a shift from the central bank’s previous view that existing frameworks were sufficient for technological innovation.