Betfair has broken off bid talks with CVC Capital Partners after the private equity firm twice upped its proposed offer to a final 950 pence ($14.60) a share.
CVC, known in Australia for losing $2 billion on its investment in Nine Entertainment, described its 950p bid for Betfair as a "full and final offer" though one conditional on due diligence, financing and a board recommendation.
But the board of British-listed Betfair, led by chairman Gerald Corbett and new chief executive Breon Corcoran, rejected that offer, saying it undervalued the company and its "attractive prospects".
Mr Corbett went back to CVC on Sunday seeking an improved offer "in conjunction with discussions"of the buy-out firm's business plan, but early on Tuesday, Betfair said it became clear "it would not be possible to agree the terms of any proposal in conjunction with a business plan that was deliverable".
Betfair, which floated 2 years ago, acts as an online exchange that allows gamblers to bet against each other, rather than against Betfair.
Betfair's Australian operations are owned in a joint venture with James Packer's casino operator Crown Ltd. CVC Asia Pacific bought Nine from Mr Packer in 2007.