The head of the Royal Bank of Scotland said it was "disappointing" that Spanish bank Santander pulled out of a deal to by 316 RBS branch offices.
The deal that would have meant the transfer of 1.8 million retail accounts broke down with Santander claiming an agreement had overshot its final deadline.
The British and Spanish banks had reached a tentative deal in August 2010, the British Broadcasting Corp. reported Saturday.
"It is of course disappointing that Santander decided to pull out of this transaction, especially for the customers and staff involved," said RBS Chief Executive Officer Stephen Hester.
He also said RBS would quickly begin the process of looking for another buyer.
The European Commission ordered RBS to divest itself of some of its assets after the British government granted it a taxpayer bailout of $58.3 billion.