The deal was announced in July 2023 with completion was subject to regulatory approvals. 

It creates a strategic partnership between XPS and SEI, leaving XPS to provide services to continue to support NPT and SEI.

The total cash consideration payable to XPS is up to £42.5m, comprising £35m initial consideration upon completion and deferred earn-out consideration of up to £7.5m based on business performance over two years after completion. 

XPS will use the proceeds to partially repay its debt facilities.

Paul Cuff, co-chief executive of XPS, said: "Everything we do is centred around helping members of pension schemes receive the best outcomes and security in retirement. This goal has underpinned the operation of National Pensions Trust for many years, and it is a high-quality master trust that serves our clients, and most importantly, the members, very well. 

"Against the backdrop of an evolving and consolidating market, we have sought a long-term strategic partner with whom we can each bring the best of what we do.”

Steve Charlton, managing director of defined contribution, EMEA and Asia, for SEI's Institutional business, said: "Two years ago we shared our ambition for the SEI Master Trust to become the market-leading master trust with the size and scale to deliver stability and help members be more confident that their financial futures are secure.

“We believe our acquisitions of the National Pensions Trust and the Atlas Master Trust in 2021 bring us closer to those goals.”

He said that industry consolidation reduces the number of smaller and sometimes less resilient schemes, bringing greater stability to the pensions landscape.

He added: “Greater stability can strengthen propositions, and we believe our proposition has gone from strength to strength. Employers choosing the SEI Master Trust and their employees will benefit from this greater stability.”

NPT was founded in 2009. It is a UK master trust with more than 60,000 members.

The SEI Master Trust provides an end-to-end solution for employers delivering defined contribution (DC) schemes.