The big four's combined share of the Australian residential mortgage market has jumped to 84.5 per cent in April, according to APRA data.
CBA holds the largest loan book, with 27.3 per cent of domestic mortgages, followed by Westpac at 25.1 per cent.
NAB owns 16.8 per cent of Australian mortgages while ANZ trails at 15.3 per cent.
In terms of growth, NAB’s loan book grew the most out of the majors in April at 0.63 per cent, or $1.3 billion in new loans written.
Putting this into perspective, NAB grew its loan book by more than the entire value of the QT Mutual Bank loan book ($1 billion) in April.
ANZ saw the second best growth of the major banks with 0.51 per cent growth in home lending in April, or $954 million in new loans written.
CBA experienced a 0.48 per cent increase, but the greatest value of new loans written at $1.6 billion
Westpac’s loan book grew by 0.47 per cent over April, the equivalent of $1.5 billion in new loans written.
Comparison website Finder.com.au found that seven lenders had reduced their variable rate mortgages out of cycle this year as competition increases in spite of the majors’ dominance.
The most recent lender to reduce a variable home loan rate out of cycle was Yellow Brick Road, which dropped its Rate Smasher Home Loan by 0.05 percentage points to 4.68 per cent. Others include ANZ, Bank of Queensland, Citibank, Homeloans, HSBC and Westpac.
Finder.com.au money expert Michelle Hutchison said borrowers could be missing out on potentially thousands of dollars by not comparing home loans and falling for a discounted interest rate.
"It's extremely important for borrowers to compare home loan deals, read between the lines, and be wary of discounted home loan rates,” Ms Hutchinson said.
"Some lenders, including the major banks, market their home loans based on a discount off their standard variable rate,” she said, but the rate you end up with could be much more than other home loans in the market.”
For example, the big four banks offer their package variable home loans for a $400,000 loan as 0.77 percentage points on average off their standard variable rates, Ms Hutchinson said.
“The actual rate that borrowers are offered for this loan size is 5.14 per cent on average,” she said.
"There are 65 variable home loans in our database that are lower than the big four banks' average discounted rate for this loan size.”
Yellow Brick Road executive chairman Mark Bouris said that it is vital for people to take control and do their research before settling on a home loan.
“People visit their bank thinking their loyalty is going to get them the best home loan rate, or they’re attracted to a special offer, oblivious to the fact that the discount rate might not be competitive in the long run,” Mr Bouris said.
“Shopping around and comparing rates can easily save a homeowner tens of thousands of dollars over the life of their loan, and that’s money better spent planning for the future than in interest payments.”