Korean Bank Deposits Drop ₩20 Trillion in One Week as AI Hacking Incident Sparks Customer Panic

The Quick Take

• South Korea's five major banks lost more than ₩20 trillion in demand deposits within a single week amid AI-aided hacking incident fears
• Time deposits at the five banks also fell ₩2.73 trillion, reversing five consecutive months of growth
• Chinese AI technology is alleged to have enabled hacking attacks on KB Kookmin and Shinhan Bank, triggering widespread customer anxiety

South Korea's five largest commercial banks — KB Kookmin, Shinhan, Hana, Woori, and NH NongHyup — collectively saw demand deposits (MMDA and instant-access accounts) plunge by over ₩20.13 trillion in just seven days to ₩655.4 trillion as of early October 2026. Time deposits simultaneously contracted by ₩2.73 trillion after five months of growth, suggesting customers are pulling liquidity not to invest elsewhere but due to safety concerns. The catalyst appears to be an AI-aided cyberattack targeting Korean banking institutions, reportedly leveraging Chinese AI technology to breach systems at KB Kookmin and Shinhan banks — triggering retail customer anxiety about deposit safety.

For Korean financial markets, the deposit outflow is significant. Demand deposits classified as investment holding funds typically flow from bank accounts into equities or money market vehicles; in this case, the flow appears motivated by safety concerns rather than investment opportunity. This is categorically different from a bull-market rotation — it is potential capital flight driven by cybersecurity fear. For the Korean banking sector (KB Financial Group, Shinhan Financial Group, Hana Financial), the incident raises compliance and reputational costs regardless of actual loss amounts. Korean Financial Services Commission and Financial Supervisory Service would likely mandate incident disclosure and system hardening, adding near-term regulatory burden.

The forward signals to watch are official disclosure from KB Kookmin and Shinhan on the nature and scope of the AI hacking incident, and any Korean FSC regulatory response mandating enhanced authentication or AI-use safeguards in banking systems. Whether the withdrawn deposits return (suggesting temporary panic) or rotate into alternative safe havens such as government bonds or physical assets will be the key indicator of lasting confidence damage. The macro variable is Korea's broader cybersecurity policy trajectory: if the incident prompts national-level AI-banking security regulations, compliance costs will be industry-wide, compressing sector ROE across the Korean banking system.

Synthesized from 2 sources.