lenders sale debts, page-7

Alinta would be a poor quality credit on the bank's balance sheets and therefor consuming a lot of capital (poor quality credit = more capital applied against the loan). Also, current margins would be loss making for them as well given current cost of funds.

All up, they can rid themselves of these loans and both save money on the loss making lending plus free up capital that can be deployed more profitably elsewhere - so hence it comes down to an opportunity cost / benefit exercise. Hence selling at a 20% discount to face value, whilst maybe recognising a potential loss of principal, would also recognise the opportunity cost of hanging on (as it could be a long term play before the loan turns "profitable".