The Co-operative Bank suffered a near trebling of losses in the first half of the year amid a major restructuring and a battle with legacy issues it admits will weigh on performance "for some time".
The UK lender posted a pre-tax loss of £204.2 million ($319 million) for the first half, nearly three times more than the £77 million loss delivered in the same period last year.
The bank said on Thursday that the net loss was due to asset sales, reduced income as it radically shrinks its balance sheet and an increase in project costs.
The results come a week after the bank escaped a £120 million fine for management failings in the years leading up to its near-collapse in 2013.
The Prudential Regulation Authority said last week the bank had "a culture which encouraged prioritising the short-term financial position of the firm at the cost of taking prudent and sustainable actions for the longer-term".
Niall Booker, chief executive of the Co-op Bank, said: "Over the first half of 2015 we have continued to make real progress delivering our turnround plan focusing on reducing our risk-weighted assets to increase our ability to withstand economic stress, on making our IT platform more robust and reshaping the bank around our individual and small business customers.
"Of course, we have always said that addressing legacy issues will continue to dominate financial performance for some time and there is considerable work ahead towards a full recovery."
However, he added: "Our results are slightly better than our plan suggested."
The bank was forced to increase its provision for conduct and legal charges by £49 million, up from £38.6 million in the first half of last year.