The Shareholders' Association says it is unacceptable to loosen rules to allow companies to tap those associated with the firm to raise money quickly.
Stock market operator NZX has changed some rules which it says will help cash-strapped firms raise capital at a time when credit is harder to come by.
The changes include shortening the time for new share issues, and raising the number of shares issued annually without seeking shareholder approval.
But the most contentious measure is relaxing rules on related-party deals to raise cash, which Shareholders' Association chairman Bruce Sheppard says he is not overly impressed with.
Mr Sheppard says he is not necessarily bothered by related-party services and remuneration as long as the price struck is fair. But he is not happy with share placements, which he says creates a moral hazard.
Commerce Minister Simon Power, who has backed the changes, says he is reassured by extra protection for investors, including a review of the rule changes after a year.