Japanese banks gain OpenAI GPT-5.5 access to strengthen cyber defenses

On May 29 Japan's finance minister announced that select domestic banks have received access to OpenAI's GPT-5.5 model to bolster defenses against cyberattacks, adding fresh AI-driven support to the equity market. This follows May 28 data showing foreign investors extended their eight-week buying streak, purchasing a net ¥1.08 trillion of Japanese stocks through May 23 and lifting year-to-date inflows to ¥11.7 trillion. Concurrently, foreigners rotated into long-duration JGBs, buying ¥1.35 trillion while selling short-term debt, signaling sustained appetite for Japanese AI-linked assets and carry trades.