Last week a committee of MPs called for Railtrack to be re-nationalised, calling the chaos which followed last year's Hatfield crash last October "simply not acceptable."
More than £800m has been wiped off Railtrack's value since Monday, when the government announced it was stripping the rail operator of some of its key responsibilities as part of a £1.5bn funding package.
The package is designed to shore up Railtrack's finances - but it also ends the company's monopoly on building new railway lines and modernising the network.
And in a further blow Railtrack has been forced to drop plans to build the second stage of the Channel Tunnel rail link, which was officially approved on Monday.
Re-nationalisation
Railtrack shares fell 33% between Monday and Tuesday and were trading at 465p by mid-morning on Wednesday, their lowest level since privatisation.
Last week a committee of MPs called for Railtrack to be re-nationalised, calling the chaos which followed last year's Hatfield crash last October "simply not acceptable."
But the recommendation, by the Commons Transport Select Committee, was dismissed by Railtrack as "enormously expensive".
However, talk of re-nationalisation may intensify if Railtrack shares sink below the 1996 flotation price.
The company will also come under renewed pressure from shareholders.
Norris steps in
As part of its new funding arrangements with the government, Railtrack has pledged not to pay any exceptional or special dividends to its shareholders over the next five years.
Deputy Prime Minister John Prescott has also struck a deal with Railtrack management to allow a new passengers' representative to be appointed to the company's board.
The company said it had also agreed "a more clearly-defined partnership" with the Strategic Rail Authority in which other companies would get involved with rail projects.
Mr Prescott said the deal with Railtrack "marks a fresh start for our railways".
Meanwhile, former Conservative transport minister and London mayoral candidate Steven Norris has put himself forward as a potential Railtrack director, according to Wednesday's Financial Times.
Mr Norris said that he would consider the chairmanship of Railtrack or possibly the new directorship.
The company said that discussions were continuing with candidates who had been on its original shortlist.
Chris Tarry, transport analyst with Commerzbank, described Railtrack's outlook statement, issued on Monday, as "alarming".