The Commerce Commission will decide early next year if the merger of media companies Fairfax and NZME will go ahead.
The companies lodged their application in May and a final decision was expected today, but is now expected by 15 March.
It said the proposal was complex and it was still assessing a number of factors.
"The Commission is continuing to assess the effects of the proposed merger on areas such as the provision of national, regional and local news content and information, including the impact on the quality, accuracy and range of the news media in New Zealand," it said in a statement.
"In addition, the Commission is assessing whether the proposed merger would enable the parties to increase prices to advertisers and consumers."
It said it now expects to make a draft decision by early November.
"This will set out the Commission's preliminary view on whether the proposed merger would be likely to result in a substantial lessening of competition as well as balancing the public benefits and detriments that it may bring about."
The watchdog said further submissions could be lodged after that, and a public meeting may be held to discuss the draft in December.
The two businesses have a combined workforce of more than 3000 people and former New Zealand Herald editor Tim Murphy has estimated a merger could cost up to 750 jobs
NZME - the New Zealand arm of Australian firm APN - owns several North Island daily newspapers including New Zealand Herald, radio stations and websites, including nzherald.co.nz and Grabone.
Fairfax operates the country's largest print media network and six websites, including the country's most-visited news website stuff.co.nz.
Fairfax's media portfolio also includes newspapers The Press, The Dominion Post and Sunday Star Times among others, magazines - such as Cuisine, TV Guide and NZ House & Garden.
The Commerce Commission is also looking at another major media merger proposal put forward by telecommunications company Vodafone and pay television operator Sky Network Television. A final decision is scheduled by 11 November but an extension seems likely.