Betfair management has come under pressure to explain itself to shareholders after throwing out a takeover bid of 950p a share.
The shares tumbled 30p to 865p yesterday, after the company confirmed that negotiations on the deal had ended, leaving them far below the bid offer from CVC and its partners Richard Koch and Antony Ball.
Since the bid began, commentators have speculated that 1,000p is the level at which an offer began to look interesting.
One shareholder said: "It wasn't far off what would have worked. If it doesn't get back up to bid levels in the fairly near future, the board will be forced to pay a special dividend."
Betfair's chairman, Gerald Corbett, said: "The board has spent considerable time assessing the various proposals. The board concluded that none of the proposals represented adequate value."
The original 880p offer was upped twice, it emerged late on Monday, to 920p and then 950p. Some think investors should have been allowed to at least vote on a deal.
Another shareholder said: "It is hard to see how they can justify not even showing the shareholders a £9.50 bid unless the share price gets there pretty quickly. I would imagine they won't want to get to the AGM with the share price £1 or more under that bid level, without having paid the difference to shareholders by means of returning cash. If they do, surely they would be voted out."
Betfair floated in October 2010 at 1,300p, a price that was dependent on surging growth in new businesses. Since then, the company has been forced to scale back its ambitions.
CVC said: "The consortium confirms it has been unable to agree financial terms with the board of Betfair and as a result has no intention of making an offer for Betfair."
Betfair's technology allows gamblers to bet online against one another at their own prices. It also offers more conventional sports betting with odds set centrally to compete with rivals in an expanding yet highly competitive sector.
Betfair has withdrawn from markets such as Greece and Germany, where regulations are not clear-cut or tax rates are punitive, and has cut 500 jobs to help save £30m in costs.