Fodor said NAB was "realistically half-way through" its ten-year technology transformation.
All large banks have struggled to create a business case for the replacement of legacy banking systems, he said. These systems have remained robust over time, but proven inflexible because of the years of multiple layers of additional technology built on top.
"There comes a point when as an organisation, particularly if you've been around for 150 years, you realise that position is not sustainable and you need to start consolidating," he said.
"The benefits of [an integrated front to backend system] are considerable when moving from 150 systems to two," he said. "There are decommissioning benefits, process efficiency benefits, licensing cost benefits - there is a long list.
"And we are making good progress on that journey - we've still got work to do but the foundations are in place now that are going to enable the benefits in that business case over the coming years."