Investors have expressed concern after ANZ Bank proposed a takeover of the Bonus Bonds scheme, but the bank says it was simply carrying out market research.
Some customers were perplexed this week when the Australian-owned bank asked them in an online survey how they would feel "if ANZ were to take over ownership of Bonus Bonds".
As part of the survey, the bank mocked up an ANZ Bonus Bonds logo.
The bank's subsidiary, ANZ Investment Services, manages Bonus Bonds, but the investment scheme is owned by a trust.
Herald readers who invested in the 40-year-old scheme felt their returns could be reduced if a single investment arm took control.
They felt any change to the scheme would be significant, as one in four New Zealanders held Bonus Bonds. It is the biggest retail investment scheme in the country, with assets of more than $2 billion.
Business commentator Brian Gaynor said he was uncertain whether ANZ could legally gain a greater stake in Bonus Bonds, but said it would disadvantage investors if they did.
"If I was a bond holder, I wouldn't like it, because it has become increasingly a gravy train for the ANZ. Certainly, the number of prizes has dropped off.
"The prizes are likely to be bigger if the investment returns are bigger. And of course, they're going to be bigger if there's a contestability."
Bonus Bonds head Glenn Stevenson said ANZ Investment Services was seeking feedback on ANZ's connection to Bonus Bonds, and it was not intending to change its management status.
"We are just doing some wider branding research to understand people's perceptions of it, and it's not an ownership question," he said.
"ANZ has had management status for 20 years, and nothing's changing in that regard."
ANZ was trying to evolve the Bonus Bonds brand and ensure that it was attractive to a younger generation.
Bonus Bonds' credit rating was downgraded last month by rating agency Standard and Poor's from AAAf to AAf.
Each month, 200,000 cash prizes are given to Bonus Bonds holders, and people can cash in their bonds at any time.