Listing large council-owned seaports and airports on the stock exchange would put added pressure on these assets to lift their game, says the Productivity Commission.
In a 278-page draft report released yesterday on freight and transport, it said a stock market listing would offer "significant potential governance improvements for larger companies" with a partial-council ownership.
Listed entities are "subject to strong, and ongoing, scrutiny and pressure for improvement" and have a share price that reacts to market conditions, the perceived quality of directors and any plans they announce, it said.
"Stock exchange rules such as those requiring regular reporting and continuous disclosure can expose poorly-performing managers, and pressure from minority shareholders and external analysts can spur the timely rectification of such problems."
Four seaports - Port of Tauranga, South Port New Zealand, Northland Port and Lyttelton Port - are already on the New Zealand stock exchange.