But those who wish to qualify for it must put up part or all of their home as equity and meet minimum deposit and equity criteria.
Newcomers to the banks must have a mortgage of at least $500,000 or savings and investments of $100,000 with HSBC while existing HSBC customers can only get the lower rate if they add another $100,000 to their mortgage debt.
Glen Tonks, head of retail banking and wealth management at HSBC New Zealand, said the rate cut was not a stunt and would not be a loss-leader for the bank.
"For us this is about growth. This is about taking market share."
Tonks said the bank had made double digit growth on its mortage book in the last year and was serious about growing its business in New Zealand.
He said the minimum requirement to have a $500k mortgage was not a hard ask and was designed to attract customers from a certain market segment.
"It is quite achievable here in Auckland. We have never struggled with that [criteria]."
But he said it was not just an Auckland offer and the bank also had relationship management teams in Wellington and Christchurch.
But don't expect the other major banks to follow suit.
SBS was the first bank to offer a sub-4 per cent mortgage rate in November last year but none of the majors have gone that low.
It is currently offering 4.15 per cent fixed for two years on a special rate.
According to interest.co.nz most of the major banks are currently offering special rates around 4.29 per cent for two years fixed.