Investors who take more risk in their KiwiSavers are generally being rewarded for it.

Morningstar has released its latest KiwiSaver survey, which shows the September quarter was a positive one for KiwiSaver providers.

The highest performance in the three months was Koura's clean energy fund, which returned 33.6 percent.

Over the year, Koura's bitcoin fund was the top performer, with a near-100 percent return.

At the bottom over three months was InvestNow's Mint Australasian equities fund and over a year, OneAnswer's international property fund.

Over a year, conservative funds returned 6.1 percent on average, moderate funds 7.3 percent, balanced funds 10.7 percent, growth funds 11.2 percent and aggressive funds 15.2 percent.

The report shows that since 2007, when KiwiSaver launched, conservative funds have had an average cumulative return of 129.6 percent, moderate funds 141.1 percent, balanced funds 184.5 percent, growth funds 240.6 percent and aggressive funds 210.2. percent.

Riskier funds are more likely to experience volatility but they should deliver better returns over the long term.

"If we look back very long term, to the start of KiwiSaver just shy of 50 funds that we know about started with KiwiSaver on 01/10/2007 in multi asset class categories and still exist today," report author Greg Bunkall wrote.

"In between we have had notable events which shook markets and included the GFC, and Covid to name but a few. While the participation throughout the whole time at category level is small in numbers, you can see generally, like other periods we look at, risk has been rewarded once again."

Koura founder Rupert Carlyon said aggressive funds would normally be expected to outperform growth funds but he said that could be due to the makeup of the market.

He said aggressive funds would be stronger performers over five years, because there had been significant growth in aggressive fund numbers in that time.

"The category was smaller until recently, when we've realised that actually, long-term investors need that extra allocation to growth and that's why you've seen a massive proliferation of funds."

He said it was easier to have those conversations about the need to take more risk after a long bull market run, where markets have performed well for investors.

"I think investors, particularly in the last four or five years, have become more aware of the market, of the need to take on risk. That's due to a combination of ultra-low interest rates ... and then also through Covid emergency money, Sharesies - we've got a whole other generation of investors who understand things a bit more."

He said retail investors were driving the market more than they ever had in the past.

"Why aren't they picking and choosing, why aren't we seeing a whole lot more different sector funds, thematic funds... I'm very biased but I'd also say with what we've seen in the last couple of months with clean energy and bitcoin, it shows doing something different can really add value in KiwiSaver."

Over five years, aggressive funds have on average returned 10 percent a year, compared to 8.3 percent for growth.

Bunkall said the September quarter was a constructive period for diversified investors.

Inflation pressures eased and major banks around the world cut rates.

ASB had the best performing conservative, balanced and moderate funds over a year.

Quay St was top of the growth and aggressive categories.

Milford remained the top-performing growth fund over 10 years.

Bunkall noted that some of Kernel's low-cost multi-asset funds had strong showings.

Top performers over 10 years

• Conservative: Milford Conservative Fund
• Moderate: Generate Moderate
• Balanced: Milford Balanced
• Growth: Milford Active Growth
• Aggressive: Booster Socially Responsible High Growth

Top performers over five years

• Conservative: Quay St Conservative
• Moderate: Milford Moderate Fund
• Balanced: Quay Street Socially Responsible Investment
• Growth: Quay St Growth
• Aggressive: SuperLife High Growth