The Shareholders Association says companies should review directors' fees more often, to prevent big catch-up hikes which alarm investors.
On Friday, shareholders in SkyCity Entertainment approved an increase in the director fee pool from $950,000 to $1.3 million. It last raised fees in 2008.
The association lobbied against the increase, saying SkyCity's performance had not been good enough to justify such a large increase.
Corporate liaison director Des Hunt says firms should review their director fees every two years, to avoid large catchups, which are hard for shareholders to assess.
And Mr Hunt says firms should be clearer about just how well they are performing.