Pushing up interest rates and holding share in an intensely competitive mortgage market is a tricky balancing act, and it’s one the big banks are struggling with.

According to the latest APRA lending data, NAB is the only big bank to have matched system growth in home loan balances over the past few months.

Lenders’ mortgage books grew 0.6 per cent in May and 1.7 per cent over the three months to the end of May.

NAB’s book grew 0.6 per cent in May and 1.8 per cent over the three months.

ANZ’s book grew 0.2 per cent in May and 0.2 per cent over three months, Commonwealth Bank’s book grew 0.4 per cent in May and 1.1 per cent over three months and Westpac’s book grew 0.3 per cent in May and 0.6 per cent over three months.

The real test is yet to come, as the mortgage market adjusts to the June rate rises and likely July increases.

Lenders that achieved above-system growth over the past three months include Australian Unity Bank (up 9.4 per cent over the three months to May), Macquarie Bank (up 8.9 per cent), HSBC Bank Australia (up 5.5 per cent), Citibank (5.4 per cent), MyState Bank (up 5.1 per cent) and Beyond Bank (up 4.9 per cent).