AIB is to sell 4,000 non-performing mortgage loans to Mars Capital Finance, the majority of which are held by owner-occupier customers.
The loans are valued at €600m, with the bank saying it would receive a payment of around €400m once the deal is completed.
AIB said 92% of the loans were connected to private dwellings, 5% covered buy-to-let properties, while 3% were across mixed use properties.
The average balance on the loans was around €300,000, with the portfolio incurring a loss of €62m in 2019.
AIB said the average amount owed in arrears was €95,000, while the accounts were in arrears for an average of 10 years.
AIB said it would now contact impacted customers about the transfer of their loan to Mars.
It said Mars would be "responsible for all regulated activities in relation to the portfolio and will also service the portfolio."