The New Zealand Super Fund grew by $3 billion in the year to March 31, despite a flat return last month.

The fund fell by 0.03 per cent in March to $25.19b, while in the past 12 months it grew by 19 per cent.

Over the last three years the fund was up by 13.6 per cent per year, while recording an average return of 18.2 per cent over the last five years.

Since its inception in 2003 the fund has returned an average of 9.5 per cent a year, well above its target of the Treasury Bill rate plus 2.5 per cent, which equated to 7.3 per cent during that period.

The fund has also outperformed its passive reference portfolio by an average of just under 1 per cent per year, adding an estimated $2.3b through active management.

As at March it had nearly two-thirds of its funds under management invested in global equities, with 11 per cent in fixed income and 6 per cent in property.

Other significant investment allocations include timber (5 per cent), New Zealand equities (5 per cent), infrastructure (4 per cent) and private equity (3 per cent).

By value, the fund's biggest holdings are in North America (34 per cent), Europe (26 per cent), New Zealand (18 per cent) and Australia (9 per cent).

The allocation to New Zealand is down from 22 per cent in March last year.

The fund's biggest equity holdings are in Z Energy ($310.4m), Fletcher Building ($172.8m), Metlifecare ($170.1m) and Telecom ($124.1m).

It has substantial security holdings in Z Energy (20 per cent holding), Metlifecare (19.9 per cent), Skellerup (6.2 per cent), Tower (5.9 per cent) and A2 Corporation (5 per cent).

- Fairfax Media