The New Zealand Superannuation Fund's purchase of more than $3 billion of shares in July has been labelled risky by some investment managers.
The fund, which will partly pay for national superannuation from 2030, sold large numbers of safer Government bonds to make the investment.
The managing director of fund manager Brook Asset Management, Mark Brighouse, says it is a big move given world share markets.
"If you invest into equities your risk is that earnings don't recover, and I guess the biggest risk for investors making this sort of shift in big steps is that you make the move too early and you find that six months or a year down the track there are much better levels to make the change."
Graham Ansell of ING says other investors faced with low returns on bonds are making similar decisions, though those making the switch are giving up certainty.
The Superannuation Fund now has 63% of its assets in global shares, up from 45% in June. It will not comment on the share purchase.