06:21 AM EDT, 05/29/2026 (MT Newswires) -- Microsoft ( MSFT )-backed (MSFT) OpenAI has granted some Japanese banks access to its latest artificial intelligence model, GPT-5.5, to defend against cyberattacks, news outlets reported Friday, citing Japanese Finance Minister Satsuki Katayama.

Katayama did not identify the banks, according to Reuters, though Nikkei reported Thursday that Mitsubishi UFJ Financial's ( MUFG ) MUFG Bank unit, Sumitomo Mitsui Financial's ( SMFG ) Sumitomo Mitsui Banking subsidiary, and Mizuho Financial's ( MFG ) Mizuho Bank are expected to gain access.

OpenAI, MUFG Bank, and Mizuho didn't immediately respond to MT Newswires' requests for comment. Efforts to reach Sumitomo Mitsui Banking were unsuccessful.

Microsoft ( MSFT ) has invested billions into generative AI chatbot maker OpenAI.