Ulster Bank has reported operating losses of £761m for 2010.
The bank is a subsidiary of the Royal Bank of Scotland which has reported a loss of £1.13bn, a bigger loss than many analysts had been expecting.
Ulster Bank said it had set aside £1.1bn for impairment charges, money set aside for bad debts.
Chief executive Cormac McCarthy said the bank was "taking the right steps to manage the recovery against challenging market conditions".
Ulster Bank made £400m from its operations but its bad debt provision meant a huge overall loss, more than double its 2009 loss.
The impairment charges were also double those reported last year.
In contrast, RBS' impairment charges fell by 33% in the last year.
Ulster is the biggest bank in NI and has a significant presence in the Irish Republic. Like all Irish banks it has suffered in the property crash.
Mr McCarthy has indicated his intention to step down once a successor has been found.
During his time in charge, Ulster Bank pioneered the 100% mortgage in the Irish Republic.
It acted as the main lender to developer Sean Dunne when he spent 375m euros buying hotels in the Ballsbridge area of Dublin in 2005 for an ill-fated redevelopment scheme.
It was also one of the main lenders to the Taggart brothers housebuilding business which collapsed with debts of up to £300m in 2008.
The UK government still owns an 84% stake in RBS after bailing the bank out during the financial crisis of 2008.