The US real estate platform is offering an all cash takeover bid of Nine’s property classifieds platform, Domain.
CoStar, which owns 16.9 per cent of Domain’s shareholding, has proposed to acquire the whole business at a cost of $2.7 billion.
Nine, which owns a 60 per cent stake, has previously stated that there are no immediate plans to offload the business.
Acting CEO Matt Stanton has begun a review of Nine’s operations and last month restructured the business into three divisions: Streaming & Broadcast; Publishing; and Marketplaces.
Domain sits in the marketplace arm which is led by chief digital officer Alex Parsons.
The Domain board is reviewing CoStar’s proposal and will appoint advisers to assist in the negotiations.