The Australian Stock Exchange has halted share trading in stock of New Zealand Herald and Newstalk ZB's parent company APN News & Media.
The New Zealand Herald Photo: RNZ
The exchange said this was pending an announcement due to be made to the market on Wednesday morning.
APN publishes The New Zealand Herald as well as operating the popular talk radio station Newstalk ZB.
In a statement, APN said the halt would last until trading starts on Wednesday, or when it makes another statement.
No other details were available.
However media reports in Australia speculate that APN is considering hiving off its New Zealand assets and merging them with the New Zealand assets of Fairfax.
Fairfax owns the news website Stuff, the newspapers The Dominion Post, The Press and the Sunday Star-Times, as well as a host of magazines, including TV Guide, Cuisine and NZ House and Garden.
Both media organisations have been under financial pressure and have shed staff to save money.
The Australian newspaper reports that rival company Fairfax Media is considering spinning off its New Zealand newspaper, magazine and digital business as the 185-year-old publisher fights for a sharemarket re-rating.
But industry sources stress the company has not yet made any decisions about its New Zealand business and several other options are on the table.
APN is also contemplating a demerger of its New Zealand assets, and The Australian says Fairfax and APN have held talks about a possible merger of their New Zealand operations.
A demerged Fairfax New Zealand could end up footing it with APN News & Media on the NZX, with APN also contemplating a demerger of its New Zealand assets, probably through a distribution of shares to existing investors, the newspaper said.
But if that option was undertaken it would be via a two-step process in which each company initially spun off their NZ businesses.
A merger of the two media rivals would bring major newspapers such as The New Zealand Herald, The Dominion Post and Christchurch's The Press under one umbrella, along with the Newstalk ZB radio network.
Fairfax has cast doubt on a possible merger, telling the Australian exchange that while it was aware of media speculation, at this stage it had nothing to disclose.