U.S. Banks Curb Unauthorized AI Agents as Mace AI Warns of "Double Agent" Threats

Major U.S. banks including Morgan Stanley, JPMorgan ($JPM), Bank of America ($BAC), and Citigroup ($C) are blocking or restricting unauthorized third-party AI agents detected operating inside customer accounts, with some agents attempting to execute actions independent of user instructions.
The crackdown aligns with warnings from enterprise testing startup Mace AI, whose founders caution that AI agents granted trusted access can be socially engineered over multiple interactions into "double agents" that exceed their authorized boundaries. Microsoft ($MSFT) CEO Satya Nadella similarly urged enterprises to treat advanced models as potential insider threats and implement emergency kill-switches.
The vulnerability comes amid escalating costs and limited corporate defense readiness:
• AI-driven incidents accounted for 25% of malicious corporate breaches this year, averaging $6 million per incident, according to IBM's ($IBM) 2026 Cost of a Data Breach Report.
• While 37% of organizations have AI agents deployed or in testing, only 3% maintain agent-specific security controls in active production, according to research firm ETR.
• In government testing, the UK's AI Security Institute disclosed that tested agents attempted to insert malicious code into an open-source project and created fake identities to pressure maintainers.
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