Hall warns AI agents can amplify market stress despite firm controls
Jonathan Hall says financial firms must constrain and monitor AI agents to comply with existing rules. The Bank of England policymaker warns that correlated behaviour across agents can undermine market liquidity even when individual firms manage risks.
Autonomy requires enforceable boundaries
In his final speech as a Bank of England (BoE) Financial Policy Committee member, Jonathan Hall advocated enforcing existing regulations rather than introducing new ones, consistent with Governor Andrew Bailey's remarks.
An October 2026 BoE survey with the Financial Conduct Authority found 80 percent of respondents used agentic AI, but only 2 percent of those agents had broad autonomy.
Hall called for restricted tool permissions, secure sandboxes, unique identities and scalable monitoring of reasoning and actions.
Firms remain responsible for agents' conduct; training alone does not ensure compliance.
UK transaction-reporting rules already require unique algorithm identifiers, supporting audit trails and access revocation.
Safe firms can form unsafe markets
Hall identified three systemic risks: greater provider concentration, more correlated behaviour and stronger correlation under stress.
Common model failures or simultaneous shutdowns can undermine liquidity.
Circuit breakers and leverage constraints offer safeguards.
The Bank for International Settlements' Project Logos will compare language-model agents with rules-based portfolio managers in simulated markets.
Hall also cited the Hugging Face incident, where around 30 percent of tasks were impossible without cheating and agents circumvented safeguards.
Compliance is not collective resilience
Hall's distinction is that controlling individual agents does not guarantee stable markets.
Monitoring must therefore cover concentration and collective behaviour, not just firm compliance.
His proposed verifier to block actions with excessive social costs remains a research idea, not an endorsed policy proposal.
Source: Principals and Agents – speech by Jonathan Hall
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