A branding specialist says the National Bank's distinctive brand is worth billions of dollars and writing it off is a mistake.
ANZ National Bank, created when ANZ bought National in 2003, has announced plans to merge the operations under the name ANZ Bank New Zealand.
The National Bank arm will cease to exist in 2014.
The chief executive of the branding company Brand New says the bank is throwing away an asset that has been in the making for years.
Dave Bassett acknowledges the company had an identity issue with two banks offering the same services, but says scrapping one brand is the wrong idea.
Mr Basset believes the company should have looked at developing the National Bank to offer different services and says ANZ National needs to be careful about how the merger is done or it might lose customers to rival banks.
ANZ National says no frontline employees will lose their jobs but about 40 fulltime staff will have to apply for other jobs and about 200 contractors will not have contracts renewed.