Bank of Ireland has revealed that more than 12,200, or 6%, of its residential mortgages are in negative equity.
It says it has also seen the percentage of mortgages in arrears double in the period since September of last year.
It comes as the bank's chairman Richard Burrows announced he is to stand down from his post after the bank's annual shareholder meeting in July.
Earlier the bank reported a pre-tax loss for the year to the end of March after taking a charge of €1.4bn for bad debts.
The €7m pre-tax loss compares with a pre-tax profit of €1.9bn a year earlier.
After once-off charges of €340m were stripped out, underlying pre-tax profits fell by more than 80% to €332m.
The bank's profits in its retail banking business in the Republic of Ireland were almost wiped out, falling to €20m from €716m a year earlier.
Mr Burrows apologised on behalf of the directors to shareholders for the loss in value of their shares and the cancellation of dividends.
He said accountability for these losses must be taken at the top. The bank said total pay for senior bank executives had been cut by a third and no bonuses would be paid this year or next year.
Chief Executive Richie Boucher said the bank faced another difficult year ahead, with lower levels of new business as economic activity falls, as well as higher impairment charges.