The New Zealand Superannuation Fund was worth $18.47 billion on January 31 after posting a return of 1.61 per cent for that month.
The fund, set up to help pay for state pensions in future years, made a one-month return of $300m after fees mainly due to "modest" gains in its global equity investments.
This brings the total return since inception to 7.55 per cent or $5.16b, from an investment since inception of $14.88b.
The fund's annualised return is 1.8 percentage points higher than the Treasury Bill rate, 0.7 percentage points short of its aspired return of T-bill rate plus 2.5 percentage points.
Last year, a rise in international share markets propelled the Fund to a 4.42 per cent return for December.