People who join conservatively managed KiwiSaver funds by default are missing out on as much as $72,000 each over their lifetimes, according to ANZ New Zealand.
Research by the bank and its funds management subsidiary OnePath New Zealand estimates about 191,000 people don't actively monitor their KiwiSaver investment and don't adjust their risk settings as a result.
If they started out in a growth fund and reduced their level of risk as they got older, they would accumulate an average $320,000 in KiwiSaver - a so-called "life stages" strategy.
By comparison, those investors are currently automatically put into conservative funds, and are only building a $248,000 nest egg, creating a funding pool of around $13.8 billion that investors and fund managers are missing out on.
"Our research demonstrates that over the long term, investors are likely to be significantly better off through the life stages approach than with the current default `conservative option'," ANZ wealth managing director John Body said in a statement.
"Over the medium to longer term, and this is what the vast majority of retirement savings plans are designed for, conservative funds can seriously disadvantage the saver."
Under the government-mandated scheme, KiwiSaver new members are automatically enrolled into one of the six default schemes with conservative settings, and ANZ wants the government to change that mandate to the life stages approach.
The Investment Savings and Insurance Association said the default approach putting KiwiSavers in conservative funds did a good job to preserve capital, "but is not the best place to be long term".
NZN