Bank of England Plans AI Agent Stress Tests Following Parliamentary Warnings

Apr 19, 2026

The Bank of England announced it will conduct specialized stress tests for AI agents in financial markets, directly responding to Treasury Committee warnings about systemic risks from autonomous AI systems exhibiting correlated or herding behaviour. Treasury Committee Chair Dame Meg Hillier praised the Bank's commitment while publicly criticizing HM Treasury for refusing to set a 2026 deadline for bringing major AI and cloud providers under the Critical Third Parties Regime, citing the rapid evolution of risks demonstrated by Anthropic's Project Mythos. The Financial Conduct Authority will publish AI best-practice examples to clarify how existing conduct rules apply to AI workflows after industry complaints about ambiguous guidance. UK banks and insurers deploying AI agents in trading and asset management now face explicit supervisory scrutiny, with firms expected to model correlated behaviour risks across their systems and the broader industry.

Bank of England's AI agent stress testing commitment

▪The Bank of England confirmed it will investigate the impact of AI agents demonstrating correlated or herding behaviour in financial markets.
▪The Bank of England's AI agent stress testing commitment is a direct response to the Treasury Committee.
▪The Bank of England's agreement to run AI-specific stress testing aims to answer concerns that synchronised AI agent behaviour could amplify market stress.
▪The Bank of England will monitor the Financial Policy Committee's view on HM Treasury's use of the Critical Third Parties Regime.

Regulatory responses and guidance from FCA and Treasury

▪The Financial Conduct Authority will share AI best-practice examples with financial services firms after MPs criticised the clarity of current guidance.
▪The Financial Conduct Authority's practice examples respond to industry complaints that rule application to AI workflows remains ambiguous.
▪The Financial Conduct Authority will publish practice examples to help firms align AI deployment with existing conduct rules.
▪HM Treasury gave no timeline for extending the Critical Third Parties Regime to cover AI and cloud providers before the end of 2026.
▪The Treasury Committee published formal responses from the Bank of England, HM Treasury and the Financial Conduct Authority to its report on AI in financial services.

Critical Third Parties Regime timeline dispute

▪Dame Meg Hillier described herself as pleased with the Bank of England's response but perplexed at Treasury inertia.
▪UK banks were preparing controlled access to Project Mythos under Financial Conduct Authority, HM Treasury and National Cyber Security Centre coordination.
▪HM Treasury has declined to commit to a 2026 deadline for bringing major AI and cloud providers into the Critical Third Parties Regime.
▪Dame Meg Hillier publicly rebuked HM Treasury for declining to commit to a 2026 deadline for the Critical Third Parties Regime.
▪Dame Meg Hillier cited Anthropic's Project Mythos in her statement, noting how quickly the risk landscape is moving.
▪The Critical Third Parties Regime is a framework that can bring cloud and AI providers under direct financial regulatory oversight.

Implications for UK financial services firms and AI providers

▪The Bank of England's monitoring role and the Treasury Committee's watchful posture mean the Critical Third Parties designation question is postponed, not settled.

Perspective of Dame Meg Hillier (Treasury Committee Chair)

▪Dame Meg Hillier believes the rapid evolution of AI capabilities, exemplified by Anthropic's Project Mythos, demands faster regulatory action.
▪Dame Meg Hillier considers HM Treasury's refusal to set a 2026 deadline for the Critical Third Parties Regime as regulatory inertia.

Perspective of Bank of England

▪The Bank of England's monitoring role over the Critical Third Parties Regime keeps the question of AI provider designation active despite HM Treasury's delay.
▪The Bank of England frames its AI stress testing initiative as directly addressing Treasury Committee concerns about systemic risks.