Shares in BSkyB closed nearly 5% lower after a day in which News Corp defied City expectations that it would dump its proposed bid for the satellite broadcaster.
Rupert Murdoch's company withdrew its offer to hive off Sky News as a separate company and said it was now ready to engage with the regulator instead.
As analysts warned the bid was looking increasingly likely to fail, News Corp said it continued to believe its proposal will not lead to "insufficient plurality in news provision".
Minutes later, Culture Secretary Jeremy Hunt announced he would refer the proposal to the Commission. News Corp now faces a six to eight month wait to see if the deal can go ahead.
BSkyB shares have plummeted 15% - wiping around £2.5 billion off the market value of the company - in the last week
As the phone-hacking scandal at the News of the World unfolded, Rupert Murdoch's plans to acquire the 61% of BSkyB that News Corp does not already own faced increasing scrutiny.
Shares fell by as much as 7% at one stage in today's session amid speculation that the bid would be scrapped. Sam Hart, an analyst at brokers Charles Stanley, dubbed the shares "politically toxic" while Panmure Gordon analyst Alex DeGroote said the deal "is all but dead".
But today's statement from News Corp suggests the organisation is fully prepared to fight for full ownership of the broadcaster.
The statement said: "Should the Secretary of State for Culture, Olympics, Media and Sport decide on this basis to refer the proposed transaction to the Competition Commission for a detailed review, News Corporation is ready to engage with the Competition Commission on substance.
"News Corporation continues to believe that, taking into account the only relevant legal test, its proposed acquisition will not lead to there being insufficient plurality in news provision in the UK."
The share price of around 715p is now in line with that originally proposed by News Corp last June when it first revealed its intentions for BSkyB ownership.
Independent directors of BSkyB said the proposal significantly undervalued the business and called for any offer to be 800p a share or more.
News Corp faces an additional threat from Ofcom, the media watchdog, which will write to police to determine whether the phone-hacking scandal impacts the company's position as a "fit and proper" licence holder.
The deal was seemingly set to get the go-ahead after News Corp agreed to spin off the Sky News part of BSkyB into a separate business to ease some of the concern over the dominance of Mr Murdoch's companies within the UK industry.
News Corp's interests include The Times and The Sun newspapers in the UK and the Wall Street Journal in America.