National Australia Bank and ANZ are leading the big four as they grab larger slices of the mortgage market, according to data from the Australian Prudential Regulatory Authority.

Home loans still serve as the biggest aid the banking sector has as its credit growth recovers. In fact, APRA stated in its latest study that the total value of banks' home loan books went up by $10.4bn to $1.32tn in October. The agency noted that investors were the fastest-growing sector.

Meanwhile, Macquarie analyst Mike Wiblin said NAB and ANZ expanded their mortgage books the fastest among the big four banks, with annualised growth rates of 9.6% and 8.8%, respectively.

APRA chairman Wayne Byres on Friday confirmed that any action it did take was likely to occur by changing the capital rules for banks, rather than via credit restrictions on borrowers.

Byres was quoted in The Age saying there was no need to announce measures any time soon.

The chairman also said the widespread use of the term "macroprudential" is the “biggest bubble.” The term implies the credit restrictions to describe the changes APRA is considering.

"The biggest bubble in this country is people using the word macroprudential."