What you are actually choosing between
Direct investing means picking and holding individual companies (or ETFs) through a brokerage. A managed fund delegates those decisions to a licensed manager running a disclosed mandate. Both routes can hold the same underlying assets — the choice is about who does the work, what it costs, how it is taxed, and how diversified each dollar is. Many NZ investors run both: a fund core plus a small direct portfolio.
Costs: per-trade versus per-year
Direct investing costs are transactional — brokerage on each trade plus currency-conversion fees on offshore orders — and stop when you stop trading. Fund costs are a percentage of your balance every year (the annual fund charge, median 0.84% across reported NZ retail funds), plus one-off buy/sell spreads. Mechanically: a buy-and-hold direct investor pays close to nothing in ongoing product fees; a frequent-trading direct investor can easily exceed a fund's annual charge in brokerage and spreads. The crossover depends on your balance and trading behaviour, not on either route being universally cheaper.
Diversification per dollar
A single fund unit spreads across everything the fund holds — often hundreds of securities. Building comparable spread directly takes many positions and many brokerage tickets, which is why small direct portfolios tend to be concentrated in a handful of names. Concentration is not automatically wrong — it is simply a different risk profile than most people assume they have. The fund's Quarterly Fund Update lists its top-10 holdings, so you can see exactly what diversification you are buying.
Tax: imputation, FIF, and the PIE cap
New Zealand has no general capital gains tax, which shapes this comparison. Direct NZ and most ASX-listed Australian shares: dividends are taxable (NZ dividends usually carry imputation credits), gains are generally not taxed for long-term investors — though trading with intent to resell can make gains taxable. Direct foreign shares beyond the ASX exemption: once total cost exceeds NZ$50,000, the FIF rules apply — you pay tax on deemed or calculated income each year even with no dividends. In a PIE managed fund, the fund handles all of this internally and your tax is capped at your PIR (max 28%) — below the 30/33/39% marginal rates that apply to direct dividend and FIF income for higher earners.
Time, temperament, and the errors each route invites
Direct investing's documented failure modes are concentration, over-trading, and selling in downturns. Fund investing's failure modes are fee inattention (paying an active charge for index-like holdings) and switching funds after one bad year. Neither route removes behaviour risk; they just move it. The disclosure regime helps on the fund side — year-by-year records against each fund's own index are public, and this site tabulates them per fund.