• UOB's replicable data migration model, a first in ASEAN, streamlined the migration process with cost savings of 40%
• Meticulous preparation before the project integration, from data mapping to staff training, helped to drive successful integration
• By prioritising minimal disruption to services and adopting some of Citigroup's best practices, customer experience throughout the integration remained strong, building trust during a sensitive time 

UOB’s acquisition of Citigroup’s ASEAN banking franchise in 2022 marked a pivotal expansion, adding over 2.4 million customers to its existing base. This ambitious growth necessitated a large-scale process of data migration and system integration. UOB effectively managed this transition, achieving significant cost savings, minimising disruptions, and solidifying its market position. By embracing a people-centric approach, UOB prioritised customer experience, adeptly leveraging both legacy and innovative technologies to ensure a seamless integration.

Citigroup’s banking franchise in Malaysia, Indonesia, Vietnam, and Thailand came at a cost of SGD 4.9 billion ($3.6 billion). This marked a significant step in strengthening UOB’s market position in Asia. With unsecured and secured lending portfolios, wealth management, and retail deposit businesses included in the acquisition, there were challenges in integrating two legacy systems that UOB and Citigroup used to scale up operations and ensure a smooth transition. As of March 2024, UOB had completed migration and integration for Malaysia and Indonesia, with Thailand and Vietnam scheduled for the second quarter of 2025.

Seamless integration through Silverlake Axis

In 2022, UOB partnered with Silverlake Axis to develop its portfolio migration software, using innovation centred on and Silverlake’s ‘3Es’ ideology of experience, expertise and execution for a seamless transition.

Synergy across different aspects of the transition was crucial for reinforcing and enhancing UOB’s regional reputation, trust, and branding in the four ASEAN countries. UOB continued its approach with Silverlake Integrated Banking Software (SIBS), an architecturally homogeneous platform that could interface directly with the IMPACTS system previously used by Citigroup. SIBS, a legacy system employed by UOB since 1997, has been progressively enhanced with custom capabilities.

Strategic decision-making, smooth transition for expanded workforce

Strong leadership and decision-making were required from stakeholders to determine the appropriate approach for a seamless transition of customers and staff. UOB chose to transition customers and products simultaneously to avoid inconvenience. At the onset of the acquisition, UOB committed to retaining almost 4,000 staff from Citigroup, placing them regionally in significant roles within UOB across business and operational functions.

Apart from Indonesia, the acquisition was completed on a legal day one basis. At this point, Citigroup staff had fully transitioned to UOB, although branding, cards, and internal infrastructure remained under the Citigroup umbrella. UOB credits this approach with allowing continued collaboration with Citigroup to facilitate a smooth transition. During the post-legal day one period, UOB paid Citigroup to manage and run the businesses until the migration was complete.

As of May 2024, UOB had rebranded all previous Citigroup branches in Thailand and Vietnam and continues this process in Malaysia. Additional efforts are being made to scale up UOB’s presence across the countries, most recently opening 15 additional branches.

In Indonesia, UOB had to transition on both a legal and operational day one basis with a deft migration of staff and infrastructure that increased the complexity of the changes. With the lack of an overlap period, there was heightened pressure on staff to immediately integrate with the UOB brand and backend systems from legal day one.

High importance was placed on retaining existing staff, especially those who also play significant roles in Indonesia. Despite these challenges, UOB credits its strict process adherence and meticulous planning and execution, which led to a successful transition.

‘Golden copy’ for streamlining data migration, minimising risks

While considering specialised data teams for each country, UOB first focused on a challenging market like Malaysia to gain efficiencies as a ‘golden copy’ before working on other countries. Innovation in using Silverlake Axis’ golden copy developed for data migration is most prominent during its development phase, structuring the appropriate strategy to transition smoothly and minimise potential risks and costs while maintaining speed-to-market efficiency to reap benefits from an early portfolio migration.

UOB and Silverlake Axis achieved this through a three-pronged data migration, transformation, and finalisation approach. Raw data was first migrated from the IMPACTs system to SIBS, a seamless process given the system compatibility between the two banks.

Data transformation involved field-level mapping, understanding the backend data used by Citigroup, and integrating it with UOB’s requirements, for example, re-mapping country-specific Citigroup codes to ISO codes used by UOB.

The final step was to transform the data into the final state for loading into UOB’s database, pending final verification.

As an additional precaution, UOB engaged Silverlake Axis to verify and reconcile the data across different stages. A separate team provided an independent overview of potential issues.

From a backend infrastructure perspective, UOB scaled up its horizontal infrastructure, specifically the central processing units and memory storage capacity to accommodate the new customer load, and extend existing hardware platform features such as resiliency, security, load balancing and provisioning, recovery and continuity.

The golden copy served as a critical blueprint that could be replicated across the four Citi markets, ensuring that the newly acquired customer data and existing accounts would be transferred into UOB’s core banking system.

Cost savings, enhanced customer experience

The golden copy factory model blueprint represents a significant undertaking in the ASEAN market, being the first successful large-scale data merger and implementation of its kind. UOB credits 40% of the savings in implementation costs to the replication model without compromising data quality and accuracy.

Staff were regularly updated on the transition process between IMPACTS and SIBS, with frequent workshops to align staff on similarities and reconcile differences between the old and new systems.

This approach allowed for speed-to-market efficiency in implementing core banking services, only requiring management of minor country-specific requirements. Comprehensive regression testing was conducted on each country’s system to ensure that features and implementation worked as expected.

UOB attributes this successful approach to allowing it to cutover in Malaysia in July 2023, followed by Indonesia in November 2023, and Thailand in April 2024. UOB is confident that its robust processes and scalable solutions will result in efficiency gains when the bank finalises its acquisition in Vietnam by the second quarter of 2025.

UOB demonstrated its commitment to a smooth transition for its customers by ensuring a seamless integration of systems and infrastructure. The bank prioritised existing and new customer relationships.

UOB also adapted best practices from Citigroup to ensure that the latter’s customers continue to receive similar product offerings. In Thailand, UOB launched its own offshore funds capability, which Citigroup previously offered. Through the acquisition, UOB learned it could supplement the banking franchise with a separate entity as a lending arm. This second entity was launched in Thailand in March 2024, before the official transition in April, offering additional credit for the bank to provide more personal loans to customers.

With millions of existing Citigroup cardholders, including supplementary cardholders, UOB committed to bringing over Citigroup's existing credit cards from the first legal operational day. The priority moving forward is to re-card all existing Citigroup cards to UOB cards of an equivalent value, with updated terms and conditions.

Cloud versus microservices strategies

While work continues on the final transition of the Citigroup infrastructure to UOB in Vietnam, UOB navigates the debate over cloud and microservices strategies, exploring potential uses of cloud internally, and for customer offerings.

The bank still relies on its robust IBM AS/400 core banking system. Although often seen as legacy technology, the IBM AS/400 continues to meet performance requirements and offers robust security benefits, making it a reliable backbone for UOB's operations.

UOB’s acquisition of Citigroup’s banking franchise, combined with its partnership with Silverlake Axis, has resulted in a smooth transition for millions of customers. This strategic move has enabled UOB to realise substantial cost savings and enhance operational efficiency, thanks to a strong emphasis on innovation and collaboration without compromising data quality and accuracy. By effectively integrating legacy and modern systems, UOB ensures robust performance and security, solidifying its position as a leader in the regional banking sector. As the bank continues to grow and evolve, it remains committed to delivering exceptional service and fostering strong customer relationships.