Australia's four largest lenders hold almost nine out of every 10 mortgages despite the Federal Government's year-long crusade to increase competition in the home lending space.

The latest figures released by the Australian Prudential Regulation Authority show that Commonwealth Bank, Westpac, National Australia Bank and ANZ account for 86.7% of the market – down slightly from 87.3% a year ago.

Commonwealth Bank tops the pack with $305 bn in home loans, followed by Westpac at $283 bn.

In the past two years, NAB has managed to put some daylight between it and ANZ. NAB currently has a mortgage book worth $176 bn compared with ANZ's $161 bn book.