Chief executive Adrian Orr says the investments and policy of the fund are fully transparent and “there is no secret in what we do.”

However, he acknowledges it is a complex issue which is under review, and there have been changes to investments.

“We take responsible share ownership very seriously and have shown leadership by adopting global standards and practices, and remaining up to date with ongoing practices.

“In applying our standards, the Guardians have made decisions to exclude some investments, and divest in some circumstances. We are also increasingly engaging with companies, usually in concert with other international investors, as we believe this has the best chance of influencing corporate behaviour. The Guardians are actively considering several issues at present with a view to making sound decisions on investments.”

Responsible investment is a complex issue and is constantly evolving. As such, the Guardians continuously review their policies and issues.

An example of the complexity of the issue is the fund’s policy on components of nuclear weapons manufacturing which is currently being considered.

“Some companies may only be involved at the periphery, with the vast majority of their production purchased on a day-to-day basis by consumers, businesses, and governments worldwide. It is important that we work through in detail the consequences of introducing a new policy before we adopt it - as we are currently doing.

“A changed policy may, for example, mean that we ask all our international investment managers to exclude shares in some major companies. We need to consider whether that is appropriate if many commercial and/or state owned entities throughout the world trade with these companies in a friendly manner. A poorly considered decision by the Guardians could, in the extreme, adversely affect New Zealand's reputation internationally and be inconsistent with best-practice portfolio management.”