OpenAI and Japan megabanks deploy GPT‑5.5 cyber model for bank security

On May 29, 2026, Japan’s finance minister said several Japanese financial institutions, including the three megabanks, have been granted access to OpenAI’s latest GPT‑5.5 model to strengthen cyber‑defence. Reports indicate the banks will use a specialized GPT‑5.5‑Cyber variant to help detect vulnerabilities and respond to sophisticated attacks.