ANZ's market share in December 2007 stood at 34.45%; at June 30 this year it was down to 30.87%. ASB's fall was less precipitous, its share dropping from 23.55% to 22.5%.

By contrast, Kiwibank's share more than doubled from 3.02% to 6.39% over the same period.

HSBC lodged its June quarter disclosure statement last week, making it the first quarter since the December quarter 2007 in which all home-lending banks' data was prepared on exactly the same basis.

The December 2007 quarter was the last in which all banks reported using Basel 1 rules and the June quarter this year is the first in which all the banks provided figures in their loan-to-valuation tables for on-balance sheet mortgages.

The figures show Bank of New Zealand lost some market share over this period, dropping from 16.83% to 16.28%, while Westpac gained some from 20.02% to 20.84%. TSB Bank showed reasonable market share growth from 1.23% to 1.44% over the period.

SBS Bank, whose market share stood at 1.08% at June 30, didn't become a registered until October 2008.

HSBC's statement showed its mortgage book grew $7.9 million to $991.5 million in the three months ended June 30, putting its market share at 0.6% compared with 0.91% at December 31, 2007.

However, HSBC's profitability fell 15.2% to $11.9 million for the three months ended June, despite charges against profit for impaired loans falling to $0.76 million in the latest three months compared with the $3.52 million charge in the June quarter last year .

HSBC's net interest income fell 6.2% to $22 million while other income sank 27.8% to $8.8 million in the three months.