The decision by Santander to walk away from a deal to buy 316 Royal Bank of Scotland Group branches cost the Spanish bank £52m.
Santander walked away from the deal after delays held up the transfer of RBS branches, and the bank signalled it was prepared to extend the deadline.
Santander UK chief executive Ana Botín says: “Our decision not to extend again the long-stop date for our planned acquisition from The Royal Bank of Scotland Group was due to the ongoing delays and our concern that the continued uncertainty regarding timing was not in the best interests of customers or staff.
“Our overriding obligation is to our existing and prospective customers and we have acted to protect their best interests.”
A provision of £52m in costs was made in its interim management statements, to reflect costs associated with the transaction.
Santander had begun investment in the infrastructure and product range ahead of the proposed acquisition, which it says will continue to support “longer term strategic goals”.
The sale had been mandated by the European Commission as part of conditions for its approval of state aid for Royal Bank of Scotland in 2009, with Santander agreeing to buy the branches in 2010.