Opus International Consultants has tried to reassure investors about a new joint venture, saying it's considering changes following claims the board is trying to erode the rights of smaller investors.
The Shareholders' Association accused the infrastructure and asset management firm of overriding minority shareholders by removing the need to get investor approval if it wanted to further develop a joint venture with a related firm, Opus International Berhad.
The resolution passed at Opus' annual meeting in Christchurch on Wednesday.
The lobby group for small investors says it had to involve the Financial Markets Authority and stock exchange operator NZX after failing to get Opus to respond to its concerns.
Shareholders' Association director Max Smith says it is not seeking to stop Opus developing commercial opportunities.
But he says the plans would stop smaller shareholders having a voice if they disapproved of its plans.
Mr Smith says shareholders must have the right to review the company's forward planning, otherwise the company can effectively spend 49.9% of its capital without the shareholders having any say in the matter.
He says the says the Shareholders' Association was pleased the company said it would report back annually on all of these matters and keep shareholders informed but does not see it as a safeguard.
Opus chairman Kerry McDonald says he thinks plenty of shareholder protection is built in, but the company will consider further measures over the next few days to allay the association's concerns.
He says Opus already files comprehensive and full reports in New Zealand.
"When the New Zealand stock exchange approved the independent assessment report, they asked us to commit to providing in the annual report each year a substantial summary of the activities of the joint venture, and we've agreed to that."
Mr McDonald says there is still a fair amount of protection in place for minority shareholders and Opus may be able to improve it.
Company seeks to expand in rail sector
Opus says the rail industry is a key area of growth for it in its loss-making Britain arm.
At its annual meeting on Wednesday, Opus told investors it is pleased with the improvement in Britain following a large contract with Hertfordshire County Council.
Opus wants to expand its presence there, and chief executive David Prentice signalled its acquisition of Opus Rail in Australia will help it win contracts in other parts of the world.
Dr Prentice says the market remains challenging in New Zealand outside of Christchurch, with local authorities tightening their belts, while Opus is also dealing with a cooling Australian economy and focus by governments on reducing debt globally.
He says the pressure remains on Opus to keep a tight rein on costs and improve productivity.