SIPP and SSAS provider Curtis Banks has bought rival Montpelier Pension Administration Services (MPAS) for an undisclosed sum.
Curtis Banks said it will continue to buy up competitors as smaller SIPP providers and administrators are crushed by regulatory pressure.
MPAS, the SIPP arm of advisory group Montpelier, closed to new business in March.
In April, MPAS accounts revealed directors wished to sell the business amid "inherent uncertainty" about its future.
The buyout will boost Curtis Banks' SIPP book to 3,000 clients, and includes the acquisition of MPAS existing adviser connections.
Rupert Curtis, managing director of Curtis Banks, pictured, said: "This puts us in contention as a top ten bespoke SIPP and SSAS provider and gives us the critical mass to support the infrastructure needed in the current regulatory climate."
Chairman Christopher Banks added: "We remain interested in acquisitions and have the resources available to fund further purchases.
"We see current regulatory expectations as a real challenge for small SIPP providers and we expect further opportunities to become available."
In February, providers warned the FSA's proposal to force SIPP providers to produce more illustration and disclosure for clients will price smaller providers out of the market.
Consultation on those proposals, contained in CP11/03, closed on 3 May.
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