Hedge fund owners looking at options to bolster funds including selling off the troubled bank.
The Co-op Bank has put itself up for sale as it looks tobuild up its capital to meet regulatory requirements.
The bank which was near collapse before a hedge fund bail out in 2013, said significant progress had been made turning around the business but added that it still expects tomake a "significant loss".
In a statement the bank said that following an annual planning review, it will now be"inviting offers".
It added: "The board is commencing a sale process, something always considered a potential outcome of the turnaround plan, alongside considering other options to build capital and meet the longer term capital requirements applicable to all UK banks."
The Co-operative Bank has around four million customers and is well known in the mortgage sector through its Platform brand.
