The quarterly bank disclosure statements are a primary source of market data and enable us to see how each bank's market share in the all-important mortgage market has changed.
All banks have now reported for the quarter to December 31, 2011, except HSBC, and the winners and losers in this key area can be revealed.
Kiwibank made the biggest marketshare gain during 2011, raising its share by +0.5% (actually +0.485%) to 6.2% from 5.7%. Kiwibank added more than NZ$1.1 billion to its mortgage book, and this now represents a massive 77.9% of their total banking assets.
The biggest bank in the country ANZ New Zealand, operator of the ANZ and National banks, also had a good year, growing its book by more than $2.1 billion in 2011, and raising its market share by +0.5% (actually +0.438%) to 31.5%.
ANZ now has 49.8% of its assets in mortgages, the highest proportion in the bank's history.
ASB has more than 65% of its assets in its mortgage book, a level that has been stable for more than three years. But ASB lost market share, dropping to 23.5% from 23.7% over 2011.
BNZ, which has the lowest level of its assets exposed to residential mortgages at 38.6%, saw its market share rise to 15.2%, a gain of +0.3%.
Westpac on the other hand saw its market share fall slightly to 19.3% from 19.4% over the year. Westpac has 52.1% of its assets in mortgages.
Banks extended their overwhelming grip on this market. Non-bank institutions, which include building societies, credit unions and finance companies, saw a fast withering with their mortgage loan books losing more than a third of their value in just twelve months.
In fact, this share has fallen by more than two thirds over the past five years.
Here is the detail ...
| NZ$ million | 2006 | 2010 | 2011 | 10-11 | Share % | |
| $ growth | ||||||
| ANZ NZ | 44,906 | 55,036 | 57,180 | + 2,144 | 31.5% | |
| ASB | 31,155 | 41,995 | 42,583 | + 588 | 23.5% | |
| BNZ | 20,973 | 26,432 | 27,626 | + 1,194 | 15.2% | |
| HSBC | 2,322 | 981 | 1,015 | + 34 | 0.6% | |
| Kiwibank | 2,978 | 10,081 | 11,209 | + 1,128 | 6.2% | |
| NBFI (per RBNZ) | 7,419 | 4,204 | 2,725 | - 1,479 | 1.5% | |
| SBS | * | 1,827 | 1,761 | - 66 | 1.0% | |
| TSB | 1,615 | 2,307 | 2,418 | + 111 | 1.3% | |
| Westpac | 25,953 | 34,302 | 34,988 | + 686 | 19.3% | |
| ---------------------- | ------------ | ------------ | ------------ | ---------- | ||
| Total market | $ 137,330 | $ 177,165 | $ 181,506 | $ 4,341 | ||
| growth % p.a. | +14.7% | +2.2% | +2.5% |
Mortgage books and mortgage brands can be slightly confusing. For example, the ASB mortgage book includes loans from the ASB, the BankDirect and the Sovereign channels. And part of the Sovereign channel includes mortgages marketed via the NZ Home Loans network. However, as NZ Home Loans now has a substantial shareholder in Kiwibank, that channel for Sovereign and ASB generates less than it once did.
The Kiwibank mortgage book includes mortgages written through the AMP network as 'AMP home loans'. And as a point of history, Kiwibank purchased a substantial portion of the HSBC mortgage book back in 2007 as a strategy to build scale.

* SBS was a building society in 2006 and its mortgage book is included in the NBFI totals.
NBFI = non bank financial institution. This data is from the RBNZ.
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