For the first time since it began operating, in 2002, the government-owned Kiwibank's share of the mortgage market stagnated, in the September quarter.
With all the banks now having lodged their disclosure statements for the quarter, the figures show Kiwibank's share, of just below 7.2 percent, has not changed since the June quarter.
Until this year, Kiwibank had been growing its mortgage book much faster than the established banks - its market share has grown from 6.5 percent in September 2011.
But its quarterly growth has been slowing this year and its September quarter growth of $134 million was the slowest since before the global financial crisis.
Kiwibank said the latest September quarter saw constrained growth for all banks in a tight and competitive market and that as it got bigger it was a challenge to hold market share.
The figures show all banks wrote $1.7 billion of net new mortgages in the three months ended September, down from $2.4 billion in the June quarter.
Bank of New Zealand, which is owned by National Australia Bank, was the last bank to lodge its September quarter statement which shows, as with the other banks, its lending to those with less than a 20 percent deposit is shrinking rapidly.
BNZ's mortgage book overall grew $303 million in the quarter but its lending to those with small deposits shrank by $207 million.