ASB's March quarter disclosure statement shows its mortgage book, using the same capital adequacy-based measure goodreturns.co.nz has used since December 2002, shrank by $12 million in the three months ended March to $37.46 billion. It has shrunk by $451 million since March 31 last year.

However, including off-balance sheet mortgages - generally those approved but not drawn down - the measure, derived from each bank's loan-to-valuation ratio (LVR) table, likely to be most comparable between the banks in future, ASB's mortgage book grew $48 million to $42.04 billion.

ASB's lack of growth is in sharp contrast to the strong growth shown by the other three major banks in the March quarter. As previously reported, BNZ's mortgage book grew by a little over $300 million, Westpac's by about $200 million and ANZ National's by about $500 million.

ASB's net profit jumped 24.5% to $132 million for the three months ended March as net interest income climbed 25.9% to $321 million. That took net profit for the nine months ended March to $415 million, a more than three-fold increase on the $96 million it earned in the same nine months a year earlier.

However, ASB's charges against profit for bad loans rose to $44 million for the three months compared to $6 million in the March quarter last year, although the charge for the nine months fell to $80 million from $133 million.