Monmouthshire Building Society Migrates £1.36 Billion Mortgage Book to Phoebus

Monmouthshire Building Society has completed the migration of its £1.36 billion mortgage book to Phoebus, marking a critical milestone in its digital transformation. For fintech professionals, this move highlights the ongoing shift among regional lenders away from legacy systems toward automated SaaS platforms to reduce operational bottlenecks and improve scalability in a competitive lending market.

What was announced

The migration involved moving more than 18,000 open and closed mortgage accounts from the Society’s previous provider, Mutual Vision, to the Phoebus servicing product. The transition was executed over a single weekend and utilized the Phoebus Migrations API to facilitate the data transfer. The book itself is valued at £1.36 billion and encompasses the Society’s entire range of lending products, including residential, commercial, development, buy-to-let, and holiday-let mortgages.

This move is a central component of Monmouthshire Building Society’s broader core transformation programme. By adopting the Phoebus platform, the Society aims to introduce significant automation into its servicing operations. The goal is to eliminate manual workarounds and address the operational bottlenecks associated with its former platform. According to the project details, the migration follows an initial go-live phase that began in April.

With the mortgage book now successfully onboarded, the Society is moving into the final phase of its transformation project. This upcoming stage will involve the migration of its savings portfolio onto the same Phoebus infrastructure. The transition to a modern servicing environment is intended to provide the Society with the flexibility to scale its operations and launch new product ranges as the market continues to evolve.

"Monmouthshire Building Society is a fantastic client, and we have worked truly collaboratively from initial go-live in April, through to getting the mortgage migration successfully delivered. The investment we have made in our mortgage and savings product, including the ability to migrate books of any size accurately and efficiently, and our people, means we are a great fit for any Society considering moving to modern SaaS technology, backed up by proven, referenceable experience."

Adam Oldfield, Chief Executive Officer at Phoebus.

The companies involved

Monmouthshire Building Society is a regional financial institution based in Newport, Wales. Founded in 1869, the Society provides a range of savings and mortgage products to its members. It has maintained a significant presence in the Welsh financial ecosystem, participating in regional initiatives to bolster the local fintech sector. The Society operates as a mutual, meaning it is owned by its members rather than shareholders, a structure that influences its long-term approach to technology investment and customer service. It currently operates under the leadership of interim chief executive officer Dawn Gunter.

Phoebus, also known as Phoebus Software, is a specialist provider of core banking and loan servicing software. The company focuses on delivering technology solutions for banks, building societies, and third-party servicers, particularly in the mortgage and savings sectors. Its platform is designed to handle the end-to-end lifecycle of financial products, from origination through to redemption. Phoebus has positioned itself as a partner for digital transformation within the building society sector, emphasizing the use of API-led migrations and SaaS-based delivery models to modernize legacy operations for mid-tier and regional lenders.

What FF News has reported before

FF News has closely followed the multi-year partnership between these two organizations. In May 2025, we reported that Monmouthshire Selects Phoebus as Partner in Major Society Transformation Programme, which set the stage for this week's migration. This was followed in October 2025 by the announcement that Monmouthshire Building Society Signs Five-Year Deal With Phoebus as Part of Digital Transformation.

Beyond their technical partnership, the Society has been active in the wider industry. In early 2026, we covered how Fintech Wales Launches New Community Academy Alongside Leading Welsh Employers, an initiative involving the Society. More recently, in August 2026, the lender's focus on service was highlighted when Revolut and Monmouthshire Building Society Lead July Customer Satisfaction Surge.

What this means

This migration signals a turning point for the UK building society sector, where the pressure to modernize is no longer optional. For regional players, the move from legacy providers to more automated, API-driven platforms is essential to compete with digital-native "challenger" lenders. The successful weekend migration of a £1.36 billion book proves that the "big bang" risk of core system replacement can be mitigated through specialized migration tools. As interest rates and lending criteria fluctuate, the ability to automate servicing and rapidly launch new products will likely separate the resilient mutuals from those hampered by manual back-office constraints.