The up-for-sale Co-operative Bank has posted losses of £477.1 million for 2016 as it continues to be hit by "legacy issues" of the past and rock-bottom interest rates.
The struggling lender announced last month that it was putting itself up for sale, four years after it nearly collapsed.
Low interest rates and higher-than-anticipated costs have made it harder for it to meet longer term UK bank regulation.
However the bank, which has around four million customers, said it was "pleased with the interest" from potential bidders so far.
Chief executive Liam Coleman said: "Obviously, we are only a few weeks into the sale process but we are pleased with the interest to date and engaging with potential bidders as planned.
"This is a great retail bank and one that is valued by our four million loyal customers. We believe there is opportunity and potential to build on the progress made and on our distinctive ethical position."
Announcing the sale in February, the bank said it had made "considerable progress in delivering a turnaround plan" since its near-demise in 2013, which came four years after its merger with the Britannia building society.
The £477.1 million loss for 2016 is lower than £610.6 million loss it made a year earlier.