KiwiSaver members ended the June quarter a combined $10 billion richer, thanks to their contributions and market returns.
And one fund returned nearly 100 percent over 12 months.
Morningstar's latest KiwiSaver survey shows returns ranged from an average 3.3 percent in the quarter for conservative fund to 11.9 percent for the aggressive category.
Morningstar said markets had benefited as investors started to look through the geopolitical tensions that dominated the start of the year. International equities had delivered solid positive returns in New Zealand dollar terms.
"New Zealand equities also recovered, although they continued to lag global peers amid subdued domestic economic conditions and relatively weak earnings expectations."
What's good debt, what's bad debt and how do I tell the difference?
Morningstar said many funds that suffered falls in the first months of the year had since recovered.
"For KiwiSaver investors, the June quarter was a reminder of how quickly market sentiment can shift once uncertainty begins to recede. Diversified portfolios that experienced heightened volatility in the March quarter generally participated well in the recovery as risk assets rallied and energy markets normalised."
Morningstar said the quarter also showed that while events offshore could trigger sharp market moves, their long-term impact was determined by whether they materially altered economic growth or the profitability of listed companies.
Morningstar said the top performer in the quarter was Koura's clean energy fund, which delivered a 31.8 percent return.
Koura founder Rupert Carlyon said clean energy funds were being boosted by AI and high oil prices. There was significant demand for energy, he said.
The lowest performance was from Koura's bitcoin scheme, which fell 13 percent.
Over a year, Kernel's global clean energy fund was the standout, up 98.4 percent, while Koura's bitcoin fund was down 41.9 percent.
Kernel founder Dean Anderson agreed there had been a surge in energy demand. "Part of that is obviously driven by AI and data centre growth... they are hungry for energy."
He said fears about energy security were also driving interest in renewable energy sources.
"Governments are looking at ways they can expedite energy security through all levers and renewables are one of them."
He said near-100 percent returns were not normal and should not be expected. "But that flows on to the broader conversation, what we are seeing in markets generally is that very wide dispersion. Some sectors are faring incredibly well where others have been very much lagging. Whether those same sectors continue to have the momentum going forward is the question mark."
Among conservative funds, Morningstar said ASB performed best over a year, up 7.9 percent, and three years, up 7.7 percent.
Of moderate funds, MAS was best over a year, up 10.7 percent, and ASB was best over three, up 9.4 percent a year.
Among balanced funds, Fisher Funds was ranked first over a year, up 16.1 percent, and Kernel's balanced fund was up 12.7 percent a year, the best over three years.
AMP was the top performer over one year among growth funds, up 21.5 percent, and three years, up 14.2 percent a year.
Among aggressive funds, Koura was top over one year with 26.5 percent and Kernel was ranked first over three years at 17.1 percent a year.
Top performers
Conservative
One year: ASB - 7.9 percent
Three years: ASB - 7.7 percent
Five years: QuayStreet - 4.4 percent
10 years: QuayStreet - 4.8 percent
Moderate
One year: MAS - 10.7 percent
Three years: ASB - 9.4 percent
Five years: Generate - 5.2 percent
10 years: MAS - 5.9 percent
Balanced
One year: Fisher Funds - 16.1 percent
Three years: Kernel - 12.7 percent
Five years: QuayStreet - 8.4 percent
10 years: Milford - 8.2 percent
Growth
One year: AMP - 21.5 percent
Three years: AMP - 14.2 percent
Five years: QuayStreet - 10.1 percent
10 years: Milford - 10.2 percent
Aggressive
One year: Koura - 26.5 percent
Three years: Kernel - 17.1 percent
Five years: SBS - 9.7 percent
10 years: Generate - 11.1 percent.