Kiwi Wealth KiwiSaver was the strongest-performing aggressive fund thanks to its 83 per cent allocation to international equities.
Murphy added that past performance was not a guide to future performance, and this year's best performers could easily be next year's worst.
The survey found that the strength of asset classes across the risk spectrum resulted in healthy returns for KiwiSaver investors across all providers and risk profiles during the March quarter, with a direct correlation seen between the allocation to growth assets and performance during the quarter.
The average aggressive and conservative funds returned 5.41 per cent and 2.89 per cent respectively, according to the survey.
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However, it was more appropriate to evaluate the performance of a KiwiSaver scheme by studying its long-term returns, Murphy said.
Aon KiwiSaver Russell and ANZ KiwiSaver continued to be the most notable performers as they were at or near the top across all five categories, he said.
"Greater international exposure than peers has meant Kiwi Wealth KiwiSaver has comfortably been the strongest performer in the aggressive category over the past three years, while a strong growth bias has led Milford KiwiSaver to the top of the balanced category," Murphy said.
KiwiSaver assets on the Morningstar database grew to NZ$27.12 billion at 31 March 2015 from NZ$954.10 million at 30 June 2008, which Murphy described as a "phenomenal growth rate".
ANZ and ASB remained the dominant players at the end of the survey period, with a steady 44 per cent of KiwiSaver assets between them, he said.
AMP retained third spot ahead of Westpac, while Fisher Funds remained in fifth spot.
The industry remained highly-concentrated Murphy said, with the six largest KiwiSaver providers accounting for 86.9 per cent of assets on Morningstar's database.
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