It hasn't always been a popular choice for the company, though.
Back in 2014, when Unity Group was started, there was some resistance from two fronts -- one from employees with a religious background who didn't believe in gay marriage and another from those thinking it was propaganda to fly rainbow flags, openly questioning why ASB were so focused on it.
"We tackle those quite differently - we're not trying to change people's personal religious beliefs, but at work there are ASB values to live by and we want an inclusive environment," says Ferguson. "Our focus is on our people, our community and our customers, which means awareness around LGBTI in each of those areas."
He says that as part of the process of creating an inclusive workplace, senior executives and ASB's leadership team are trained in LGBTI awareness and the Unity Group is visible on the intranet site with a diversity and inclusion community page, as well as staff being encouraged to celebrate special days, such as Wear Purple Day, where staff can dress up a branch or work station in purple and vie for competitions, alongside the education and awareness component.
There's also the IDAHOT day (an International Day of Homophobia and Transphobia awareness) and badges to identify the community. For instance, Ferguson wears a Unity Group badge to identify him as someone an LGBTI employee can talk to about any issues they're having.
ASB chief executive Barbara Chapman says participation in the Rainbow Tick programme reflects a belief in the importance of diversity across all levels of the bank and she points to "an enormous body of evidence as to the benefits that diversity of thought, insights, perspectives and experiences bring to organisational performance".
"Displaying the Rainbow Tick is a public demonstration of our commitment to ensure that as an organisation we are creating an inclusive environment for members of the LGBTI communities," says Chapman. "We truly want people from all groups to bring their 'whole selves' to work and to create dynamic and innovative teams attuned to all our customers."
ASB's support of the LGBTI community also led to presence at Auckland Pride festivals, at Auckland's Pride Parade and at Auckland's Big Gay Out. ASB has also assisted with RainbowYouth's office relocation, donated to their 25th anniversary celebration and funded two $2500 RainbowYouth scholarships, as well as the production of limited edition ASB Rainbow eft-pos cards and sponsorship of the New Zealand Falcons gay rugby team. "When Ian Thorpe came out as gay he lost a few sponsors," says Henderson. "I was proud that ASB changed all their sponsorship agreements after that happened and put a clause in contracts that said they would not be compromised in that event in future."
The bank is also launching a gender-neutral Mx title for people who don't identify as either Mr or Ms, and they have a confidential email for people to ask questions about the LGBTI policy or how to deal with customers or staff if they see any bullying around this issue.
Educational lunches are also part of the forward-thinking organisation's initiatives around bringing LGBTI issues to light in the workplace.
Last year, ASB was named the New Zealand Bank of the Year by The Banker magazine in the UK for the fourth year, and ASB Unity was recognised with a Positive Inclusion award at the New Zealand Diversity Awards. It seems balancing diversity and business interests is proving a winning formula.