A market-leading fixed five-year home loan interest rate of 4.99 per cent is designed to make some noise in the New Zealand market and revalidate the benefits of a membership bank, SBS Bank chief executive Wayne Evans says.

The rate, which the bank describes as game-changing, is available for members (existing customers) and their family and friends and is open for a strictly limited time.

Evans said they wanted to keep the rate open for as long as possible, but it would be reviewed daily. The primary purpose was to recognise SBS Bank's existing customers with another tangible benefit of membership.

"I think we need to revalidate why we exist and the key is we're a member bank."

The rate is for new lending over $100,000, but members who introduce eligible family and friends will be eligible without having to present new lending of over $100,000. It is available for residential lending only.

The bank's investors were predominantly older and the initiative was designed to bring in the "nieces and nephews" of those existing customers.

SBS Bank was focused on the "long game" benefits of growing the customer base.

Evans said he challenged the bank's executive as to how it could achieve a sub-5 per cent rate and "make a bit of noise in the market".

"For a small bank we have consistently provided some of the best residential mortgage offers in the market," he said.

There had not been any competitor reaction yet, but that would be more likely to come after Thursday's Official Cash Rate review by the Reserve Bank.

The move comes on top of last month's news that SBS Bank had nearly eclipsed last year's $22 million surplus just nine months into the 2014-15 year - posting a $20.9m pre-tax result.

Evans said the busy period of activity for the bank would continue with an announcement expected about the acquisition of a new asset.