Japan Megabanks Set to Win Mythos Access After Bessent Visit

Japan’s three megabanks—MUFG Bank, Sumitomo Mitsui Banking Corp. and Mizuho Bank—are set to gain access to Anthropic’s advanced AI model Mythos, potentially as early as the end of May after discussions during US Treasury Secretary Scott Bessent’s Tokyo visit. The expansion follows limited initial access that included only JPMorgan and has raised dual market implications: heightened cybersecurity concerns for banks given Mythos’s ability to spot software vulnerabilities, and renewed investor optimism for Anthropic as it eyes fundraising at a valuation above $900 billion. Japanese authorities are convening a public‑private working group led by the Financial Services Agency to tighten cyber safeguards, a development that could influence risk premiums for Japan’s financial sector and broader investor sentiment toward technology exposure in the Japan 225 index.