Finance / Banking
Sony Bank: Developing the core banking system
- Company
- Sony Bank
- Country
- Japan
- Adoption stage
- In operation
- Source published
- In use from
- Date basis
- The date the source was published. It can differ from the date adoption started.
- How the source was checked
- Read the full source text
The work problem
For a Japanese financial company it takes months to years from planning a new service to releasing it. Development costs are large and the development process is complex, so responding quickly to market change was difficult. Sony Bank had handled its core banking system under the same conditions.
Technology and data
Sony Bank uses Fujitsu Core Banking xBank, Fujitsu's core banking solution. The solution has a cloud native architecture and runs on AWS. AI agents were assembled around Anthropic's Claude and Claude Code on Amazon Bedrock. The agents refer to the design documents, source code and test assets of the Sony Bank core banking system throughout the development process. Each agent connects to the development assets and tools it needs and supports the work, while judgement, approval and quality assurance stay with people. The scope of application was widened in stages across the core process from design through build and test.
Results
The two companies started applying it in September 2025. As of 2026 they said that across the process from basic design to integration testing, effort fell by 40 percent and development time by 30 percent. By process step, they explained that impact assessment effort at the basic design stage fell by up to 90 percent and design document writing effort at the detailed design stage by up to 40 percent. They said the source code generation rate at the implementation stage was 99 percent and the reduction in test execution effort at the integration testing stage was up to 90 percent.
Limits and open questions
The figures disclosed are effort and duration within the development process. They do not mean the bank's overall operating cost or the speed of service release changed at the same rate.
Sources
- Sony Bank and Fujitsu apply Generative AI to Core Banking System Development | Fujitsu Globalglobal.fujitsu, Accessed
Compiled from public sources. These are not results from ATF Works customers.