Commonwealth Bank modernizes core banking, improving response times by 30%

As Australia’s largest bank, CommBank operates critical national financial infrastructure, serving around 17 million customers and processing more than 70 million transactions each day. Digital experiences now shape what customers expect from banking, from intuitive apps to personalized services. Having previously transformed its core banking platform to support the rise of digital banking, CommBank recognized that a new generation of AI-driven and highly personalized experiences would require more flexible foundations. The bank therefore set out to modernize its SAP-based core banking platform and establish a cloud foundation capable of supporting real-time data, personalization, and future innovation.

That ambition came with high stakes. The core platform underpins about 40 percent of Australia’s payments, so CommBank had to modernize its SAP-based system without disrupting the services that customers, businesses, and the wider economy rely on. To reduce risk, the bank needed deep engineering expertise and close collaboration across multiple teams to deliver a transformation of this scale.

CommBank chose AWS, its primary cloud provider, to modernize its core banking platform on SAP and keep it closely integrated with the bank’s critical systems. CommBank worked with AWS and technology partners, including Accenture and Red Hat, to reduce risk across the project.

Through technical workshops with AWS and SAP, the team evaluated architecture trade-offs across performance, resilience, and scalability. AWS product engineering teams also helped optimize services for CommBank’s real-time transactional SAP banking workload.

Over 18 months, CommBank transformed its core banking platform while minimizing change across the wider organization. The bank re-engineered the core while keeping upstream and downstream interfaces largely consistent, so connected applications could continue working with the modernized platform without major refactoring. "Replacing a mission-critical core required partners we could trust,” states Simon Davies general manager, Retail Platforms and Engineering, Commonwealth Bank. “Accenture and AWS helped us modernize our SAP platform while preserving stability at scale."

CommBank deployed SAP S/4HANA on Amazon Elastic Compute Cloud (Amazon EC2) U7i high-memory instances, with Amazon Elastic Block Store (Amazon EBS) io2 Block Express and Amazon FSx for NetApp ONTAP providing the storage foundation. During the final cutover, customers could continue to log in, view their accounts and transaction history, and make certain payments, even while the core was offline for three hours.

Following the migration, CommBank gained a more responsive data foundation. After moving 70 terabytes of data and completing 8,000 end-to-end tests, the bank can now stream core banking events into its data platform in real time, helping teams use information while it is still relevant. Using Amazon Managed Streaming for Apache Kafka (Amazon MSK), CommBank streams approximately 26 million core banking events a day into a data repository built on Amazon Simple Storage Service (Amazon S3).

This real-time data flow reduces friction across the bank and creates new opportunities for AI-driven customer experiences. CommBank is also using Amazon Bedrock to build generative AI applications, including CommBank Companion, an AI-enabled experience that helps customers better understand and manage their banking, from everyday spending to running a business.

“With our core banking platform on AWS, the barrier to AI innovation is lower because the services are continually adapting and evolving,” says Davies.

By modernizing its core banking platform, CommBank improved operational performance while creating a foundation for future innovation. The modernized platform delivers 30 percent faster response times and reduces daily operating costs by 30 percent, helping the bank redirect resources toward new digital capabilities. CommBank completed the transformation without disrupting its streak of 42 consecutive months of rising customer Net Promoter Score (NPS) across its Retail Banking business.

The bank also benefits from a simpler operating model, giving teams greater visibility into platform performance and enabling faster issue resolution. By reducing reliance on fragmented specialist skills and increasing automation, CommBank has streamlined day-to-day operations and created a more adaptable platform that can evolve with changing business and customer needs.

Davies says, "We needed a platform that's flexible and adaptable and can scale with changing demands. It's nearly impossible to predict what those demands will look like in 1–2 years' time, but now we have a foundation that we can adapt and evolve on."