Britain's crisis-hit Co-operative Bank on Monday revealed that it needed another £400 million ($660 million, 480 million euros) of fresh capital to help to fill a hole in its finances.
Co-op said in a statement that it would seek the money via a sale of shares in the coming months.
The bank, which prides itself on ethical investments, said in a statement that it needed the cash for higher-than-expected compensation costs for the mis-selling of payment protection insurance on loans.
It also took a big hit from mis-selling interest rate hedging products, known as swaps, to small businesses.
In addition, the lender faced higher-than-expected restructuring costs.
"As a result of these additional costs and in order to restore the capital buffer... we intend to raise around £400 million of additional capital," the group said.
The troubled bank also warned that it expected to post a 2013 pre-tax loss of between £1.2 billion and £1.3 billion.
Monday's news comes two weeks after Euan Sutherland resigned as Co-op Group chief executive, blaming the failure to reform the governance of the mostly mutual company that runs also supermarkets and funeral parlours.
The Co-op Bank meanwhile came close to collapse last year after it was ordered by regulators to increase its capital cushion by £1.5 billion.
The bank was subsequently forced to hand control to US hedge funds in a restructuring aimed at plugging the vast black hole.
Co-op Bank slumped into fresh crisis last November after its former chairman Paul Flowers, a Methodist minister, was filmed allegedly planning to buy illegal drugs.
The bank now faces a series of investigations into what went wrong, and ongoing questions over the appointment and suitability of Flowers, who is said to have lacked knowledge of the financial sector.