Many New Zealanders are choosing to transfer out of or between KiwiSaver schemes being run by the country's five major banks, according to new research.
An academic said the findings could be an indication that people were chasing quick returns instead of taking a long-term approach.
Massey University said the five major banks - ANZ National, ASB, Bank of New Zealand, Kiwibank and Westpac - collectively had 28,139 members transfer out of their KiwiSaver funds in the year ended March 31, 2012.
That represented 58.7 per cent of the 48,000 people that transferred into the banks in the same period, meaning they had a net gain of around 20,000.
Dr Claire Matthews, Massey's director of financial planning, said the findings came as a major surprise because they went against previous thinking.
"We really wanted to understand what KiwiSaver members actually do in terms of their investment behaviour - not what they say they do."
In a survey conducted for the Financial Services Institute of Australasia (FINSIA), KiwiSaver members said they preferred having their KiwiSaver account with a bank so they could see their balance via online banking.
"People are saying that's what they like but then on the other hand, what their actual behaviour is showing is they're going away from the banks," Matthews said.
This high turnover could be a result of members constantly monitoring their account and their funds' performance, and choosing to move when performance was poor.
Matthews said that would be a concerning trend and one which showed investment immaturity.
"While investors do appear to be chasing returns and avoiding fees, that's not always the best approach to a long-term investment.
"Both returns and fees are important but it's a sign of an immature market when investors chase historic returns with an expectation that they provide some indication of future returns, which of course they don't."
Chris Douglas, co-head of research for Morningstar Australasia, said members could well be shifting between banks, rather than leaving for smaller providers.
"Every time I speak to the banks, they seem to be very comfortable with their sign up rates. I've not heard people are leaving the banks altogether."
But Douglas said members were clearly paying more attention to their KiwiSaver investments as the balances started to rise.
"It's very rare to see a product like KiwiSaver where it's so easy to switch - it's very clean and simple. The downside is you get people switching for the wrong reasons."
Members could be changing providers for a whole range of reasons though, not just chasing better returns, he said.
"It could be they're going to get a mortgage at a bank and switching KiwiSaver at the same time."
Others might have moved because they wanted better communication from their provider.
Douglas said although KiwiSaver had been running for more than five years, it was probably still too early to be changing providers based on results so far.
KiwiSaver membership has grown to just over 2 million since its launch in 2007.