A fund manager and economist says performance tables for KiwiSaver funds are misleading investors.
A survey of 142 KiwiSaver funds by investment research company Morningstar has found just 31 posted a positive result in the three months to June.
But Gareth Morgan, whose company's growth fund and balanced fund were ranked among the worst performers in their sectors, says Morningstar is not comparing apples with apples.
Dr Morgan says it fails to take into account the actual return to investors after fees and tax, and does not consider the current market value of assets.
He says there is an urgent need for regulators to set up their own independent comparison of performance.
Dr Morgan says Morningstar just publishes what it is given and some companies manipulate returns by spreading losses over many months.
The Morningstar survey found some of the worst-performing funds attracted some of the larger sums from investors.
The largest fund, ASB's default fund with more than $600 million, ranked 10th out of 16 funds for performance over two years in the conservative sector.
However, Morningstar co-director of research Chris Douglas says choosing a KiwiSaver fund manager on the basis of past performance alone would be misguided, as the highest fliers can sometimes fall the fastest.