The financial services industry is undergoing a significant transformation, driven by the need to generate new revenue streams and boost profitability. This shift is powered by the adoption of advanced technologies and evolving business models designed to meet growing client expectations. Like many industries, financial services firms are focused on optimizing cost-to-serve mechanisms and improving operational efficiency. However, they face unique challenges due to strict regulations, heightened scrutiny of IT risks, and increasing dependencies on third-party vendors.
AI, data analytics, and cloud technologies present valuable opportunities to tackle these challenges. Yet, their full potential remains limited by legacy systems—what I refer to as the “banking technology trap.” Many financial institutions still rely on outdated, complex mainframe systems that hinder progress. Although some have successfully migrated peripheral workloads to the cloud, the modernization of core systems remains critical. This essential step has been delayed for too long, leaving the financial services sector trailing other industries in cloud adoption.
The combination of legacy infrastructure, outdated technologies, limited expertise, shifting business demands, and growing regulatory pressures has created a perfect storm, driving the need for urgent and decisive action. As a result, financial services companies are finally breaking the status quo and making long-overdue moves toward modernization.
There is no one-size-fits-all approach to core modernization. Successful transformations require a tailored mix of strategies aligned with each organization’s unique starting point, context, and goals. By combining various modernization archetypes and patterns in parallel and sequential steps, financial services companies can craft a roadmap that maximizes value.
In-place optimization to enhance efficiency, reliability, and service quality
For domains without an immediate business need, clear business case, or urgent obsolescence concerns, yet where opportunities to improve efficiency, reliability, scalability, and service quality still exist, the solution could lie within the existing technology framework. Some potential approaches include:
- Optimizing Existing Technology: Fine-tuning configurations, rationalizing online and batch workloads, and enhancing data access to improve overall performance.
- Revisiting Vendor Contracts: Renegotiating contracts to unlock cost-saving opportunities or explore consolidation options that will improve operational efficiency.
- Partial Outsourcing: Offloading specific services or components to specialized providers, enabling focus on core competencies while improving efficiency.
- Adopting Mainframe as a Service (MFaaS): Leveraging MFaaS solutions to modernize mainframe operations, offering flexibility, cost-effectiveness, and scalability without overhauling the entire infrastructure.
Iso-functional technology modernization to leverage new technologies
For many business functions, products, and platforms, upgrading the underlying technology without altering the existing functionality can offer substantial benefits in cost, service, scalability, and productivity. Here are some viable options for achieving these improvements:
- Read Off-loading: Migrating database read workloads to the cloud can reduce the processing load on high-cost legacy systems while allowing critical write functions to remain on the legacy system. This approach helps with scalability and provides access to more innovative, high-performance software development environments in areas where speed and flexibility are crucial. By maintaining write functions on the existing system, businesses can minimize risk, especially for critical financial tasks that don’t require frequent innovation. Key considerations include data access and replication methods, as well as real-time data synchronization requirements.
- Re-platforming (Lift and Shift): This strategy involves migrating legacy code to cloud-based, emulated mainframe environments, providing access to cost-effective, scalable computing, improved data access, enhanced event capabilities, and DevSecOps frameworks. Since the source code remains unchanged, this approach reduces risks and minimizes the need for specialized knowledge and resources. Essential considerations include establishing technical foundations, ensuring parallel run capabilities, and managing batch scheduling for smooth transitions.
- Refactoring: Rewriting legacy code in modern languages like Java or Python for deployment in a cloud-based architecture can help unlock the full potential of the cloud. This process involves creating new development environments (IDEs), landing architecture, and configuration, after which the source code can be rewritten either manually or automatically. The emergence of AI-driven tools, such as ‘co-pilot ‘-like systems, is revolutionizing both manual and automated rewriting processes, enhancing the quality, maintainability, and performance of the new code and making it more efficient and adaptable in the long term.
Functional transformation and legacy exit for business reinvention
When legacy systems and functions fail to meet strategic objectives, re-engineering or re-imagining their functionality becomes essential. Several options for achieving this transformation include:
- Custom-built Solution: Developing in-house business and technology capabilities to enable market differentiation. A custom-built solution isn’t about reinventing the wheel but creating tools that will allow the delivery of personalized, differentiated products, services, and experiences. Leveraging generative AI can significantly enhance creativity, quality, and productivity in software development, helping organizations stay ahead in a competitive market.
- Packaged Solution: Upgrading or replacing existing core systems with a packaged solution from a market vendor, either partially or entirely. Most banking software vendors support interoperability and composability, offering modular capabilities that can be integrated and customized for specific business needs rather than requiring a complete end-to-end solution. However, when upgrading to an end-to-end core banking package, it’s critical to assess the number of versions that need bridging, the technological evolution between versions, and the extent of customization required in the installed version.
- Greenfield Approach: Launching a new digital brand built on a modern technology stack to deliver innovative products and services. This approach can be a standalone offering, a testbed for migrating the customer base in the future, or a strategy for entering new markets with a fresh, differentiated presence.
- Side Core: Implementing a new core system alongside the legacy system to support new products and services with incredible speed, flexibility, and improved capabilities. In some cases, the new core system becomes the target for gradually migrating the full range of products and services, ultimately phasing out the legacy platform. In other cases, it is simply one component of a broader systems strategy. Key considerations include functional coverage of the target platform, extracting cross-product functions from the legacy system, and addressing technical integration, orchestration, and coexistence.
- Core as a Service: Originally suited for smaller institutions, this model is now expanding to more prominent players through a composable model that integrates core functions as services. While still maturing, this approach is expected to grow significantly in the near future, providing flexibility and scalability for organizations of all sizes.
Systematic Decommissioning is a critical process for phasing out legacy systems as part of the modernization journey. Effective planning is essential to ensure the legacy components are efficiently retired as new systems become operational, minimizing disruptions while transitioning to modernized infrastructures.

Interoperability and composability ensure a fit-for-purpose approach.
The “secret sauce” that ties together short-, medium–, and long-term applicable patterns is a robust interoperability/composability landing architecture. This architecture acts as the structural foundation for system coexistence. It enables key concepts such as decoupling and isolating different layers, integrating various technologies and hosting models, orchestrating services, ensuring technical compatibility, and achieving logical coexistence through cross-product abstractions and standardized microservices frameworks.
By adopting this interoperability/composability approach and architecture, organizations can mitigate the risks of legacy modernization programs. It allows legacy systems and next-gen solutions to coexist seamlessly, whether on-premises or in the cloud. This flexibility empowers businesses to craft a transformation roadmap that aligns with their pace, chosen transformation patterns, and investment capabilities, ensuring they achieve timely business outcomes. Learn more about interoperability/composability in core banking modernization here.
How to start core banking modernization: Think big and start small.
Crafting a successful transformation strategy begins with a clear understanding of your current state and future aspirations—going beyond just IT. This vision will serve as the guiding force for a gradual transformation roadmap that aligns with your North Star goal. Start by defining a high-level vision (think considerable) and selecting the optimal modernization approach for each domain, application, or platform. From there, build a roadmap that starts small to minimize risks, balance investments, and ensure timely business outcomes.
Read here for more insights on building a compelling business case for core modernization. If you’re ready to explore core modernization options and develop a customized strategy, feel free to contact me here.
Key Strategies for Modernization
Assess the Current System
Before beginning the modernization process, it’s essential to conduct a comprehensive evaluation of your existing mainframe and core banking infrastructure. Key steps in this assessment include:
- Identifying bottlenecks and limitations.
- Analyzing current and future business requirements.
- Evaluating the potential costs and risks involved.
Adopt a Phased Approach
Modernization doesn’t need to be a one-time event. A phased approach allows organizations to transition gradually without disrupting daily operations:
- Rehosting: Migrate legacy applications to modern platforms with minimal modifications.
- Refactoring: Re-engineer core functionalities to enhance performance and scalability.
- Replacing: Swap out outdated components for modern solutions.
Leverage Cloud Computing
Cloud platforms provide unmatched scalability, cost-effectiveness, and flexibility. Migrating core banking systems to the cloud offers several benefits for financial institutions:
- Reduced infrastructure costs.
- Real-time data access and processing capabilities.
- Improved disaster recovery and business continuity.
Implement APIs and Microservices
Shifting from monolithic architectures to microservices and APIs enables smooth integration with third-party services and accelerates innovation. Advantages include:
- Faster time-to-market for new features.
- Enhanced scalability and fault isolation.
- Simplified integration with fintech and payment solutions.
- (Explore the impact of digital technologies on payments in The Future of Payments in 2025.)
Embrace Artificial Intelligence and Machine Learning
AI and machine learning have the potential to transform core banking systems by improving customer service, fraud detection, and decision-making. Key applications include:
- Predictive analytics for personalized banking experiences.
- Automated credit scoring and risk assessment.
- Real-time fraud detection and anomaly prevention.
Adopt DevOps Practices
DevOps practices ensure continuous integration and delivery (CI/CD), allowing for rapid updates and new feature deployment. Benefits of this approach include:
- Faster time-to-market.
- Improved collaboration between development and operations teams.
- Enhanced system reliability and performance.
Prioritize Security and Compliance
Modernization efforts must address security vulnerabilities and ensure compliance with industry regulations. Key strategies include:
- Implementing advanced encryption and authentication protocols.
- Ensuring real-time monitoring and threat detection.
- Maintaining audit trails for regulatory reporting.
Frequently Asked Question
What is core banking system modernization?
Core banking system modernization refers to the process of upgrading, replacing, or transforming the technology infrastructure of a bank’s core systems to improve efficiency, scalability, and flexibility while meeting modern business and regulatory requirements.
Why is modernizing mainframe systems critical for banks?
Mainframe systems often run outdated technologies that hinder innovation and scalability. Modernizing these systems allows banks to streamline operations, enhance customer experiences, reduce costs, and remain competitive in a rapidly evolving digital landscape.
What are the key strategies for modernizing core banking systems?
Key strategies include re-platforming (lifting and shifting to the cloud), re-engineering legacy systems, adopting modular or composable solutions, implementing AI and automation, and leveraging cloud technologies for scalability and flexibility.
What is the “banking technology trap,” and how does it affect modernization?
The “banking technology trap” refers to the reliance on outdated legacy systems that hinder the adoption of newer, more efficient technologies like AI, cloud, and data analytics, slowing down digital transformation and limiting innovation.
How can a phased approach help in core banking modernization?
A phased approach allows banks to mitigate risks by breaking down the transformation process into manageable steps, such as migrating peripheral workloads first, followed by core system updates, reducing disruption, and optimizing costs.
What role does AI play in core banking modernization?
AI helps streamline operations, enhance decision-making, automate routine tasks, and personalize customer experiences. It can also assist in improving fraud detection, risk management, and compliance monitoring.
What are the challenges of modernizing legacy core banking systems?
Challenges include integration with existing infrastructure, data migration, managing regulatory compliance, training staff on new systems, and ensuring minimal disruption to business operations during the transition.
Conclusion
Modernizing mainframe and core banking systems is a crucial step for financial institutions looking to stay competitive, enhance efficiency, and meet evolving customer expectations. By following a strategic approach that includes assessing current systems, adopting a phased modernization strategy, leveraging cloud computing, implementing APIs and microservices, embracing AI and machine learning, and adopting DevOps practices, banks can navigate this transformation successfully. Additionally, prioritizing security and compliance throughout the process ensures that modernization efforts align with regulatory standards while minimizing risks.