Industry fund SunSuper will replace its custody services provider National Australia Bank Asset Servicing (NAS) with State Street next year, after the $18.5 billion fund completed a tender.

SunSuper had used NAS for more than a decade, but the increasing sophistication of the fund's investment management activities required a change of custodian, SunSuper chief investment officer David Hartley said.

"State Street has been probably more involved in investment managers and I think over time we are getting more towards that end of the spectrum, as opposed to the super funds end, as we get more sophisticated," Hartley said.

"In terms of our evolving needs, it makes more sense for us to use State Street going forward, but NAS has been very good."

From July, Sunsuper has offered 20 investment options, including six diversified options and 12 single asset class options.

It also provides two specialised options: an ethical, environmental and socially responsible investment option and a capital-guaranteed option.

The fund offers both active and index options, single manager and multi-manager options and hedged and unhedged options.

Hartley said the transition to the new custodian would take place in the first half of 2012.

Meanwhile, NAS has signed a memorandum of understanding with investment administration provider MMc to enter into a partnership, offering fund administration services to the New Zealand market.

NAS already offers custodian services in New Zealand, but said the introduction of KiwiSaver - the country's voluntary superannuation scheme - had increased the demand for financial services among Australian fund managers with New Zealand operations.