The New Zealand Superannuation Fund made a loss in November due to falling world sharemarkets.
The fund's monthly investment results show a loss before tax, but after fees, of 0.54% for November.
The fund had made a profit of 6.66% in October, but there were losses the preceding three months, and an overall loss for the financial year to date.
The latest figures show the fund standing at $17.6 billion in total value, down from $19 billion six months ago.
In its statement, the fund stresses that it is in the investment business long term and that short-term fluctuations in the market are of limited relevance.
The function of the Superannuation Fund, sometimes known as the Cullen Fund, is to help pay for future superannuation costs for an expanded population of elderly people.