Its general disclosure statement for the quarter shows net profit fell 38% to $62 million, taking the fall in profit for the year ended September to 55.9% to $248 million.

The bank's charges against profit for bad loans rose $105 million in the September quarter, taking annual charges to $620 million.

Most of Westpac's burgeoning bad debts are from its corporate lending - mortgages gone bad accounted for $102 million of the annual charges.

The Westpac subsidiary's net interest income also slipped in the quarter, falling 8.1% to $295 million from the same quarter a year earlier, although annual net interest income was up 3.2% at $1.32 billion.

Westpac's mortgage book totalled $27.38 billion at September 30, up $358 million from June 30 which compared with the $136 million growth in the June quarter. Using Reserve Bank figures as a proxy for the market, Westpac's new mortgage lending accounted for 23.4% of the increase in lending on mortgages by registered banks in the September quarter.

That meant its market share rose from just below 17% at June 30 to 17.05% at September 30.

Westpac had a further $5.24 billion in undrawn mortgages at September 30.

Westpac's mortgages with loan-to-value ratios (LVRs) above 80% continued to decline to 25.8% of its mortgage book at September 30 from 26.9% three months earlier and 28.2% in December 2008.