When the plan was announced it seemed a formality. A rival bid from legendary investor Carl Icahn emerged, but no-one took it too seriously – at first. Now it looks like Icahn could derail the whole thing, with a counter-bid that would give him a higher stake and keep the company public.

Many major Dell investors have swung Icahn’s way in the last week, and results of the vote are no longer a foregone conclusion. Blackstone Group, an influential private equity firm that owns 4.4% of Dell’s stock, now supports the Icahn plan. Forbes magazine says that other major investors have followed suit, and that more than 20% of Dell shareholders are now publicly against the privatisation scheme.

Michael Dell owns 16% of the company he founded in a university dorm room in 1984, but he and his associates are not permitted to vote.

It would be the largest privatisation deal in IT history. It values each share at $13.65, a significant 37% premium over the average closing share price over the last three months. Shares went up after the deal was announced, but in a sure sign that things are not going well they have now dropped back to $12.76, their lowest in three months.

The Dell board unanimously approved the agreement, on the condition that there would be a vote of the unaffiliated stockholders. They expected these voters would fall into line. They have not.

The privatisation makes sense, to many at least. Dell lost nearly a third of its value last year as the epicentre of computing moved from Dell’s traditional strengths of PCs and servers to the mobile market. As a private company Dell could make technology investments and adopt strategies that would not be affected by the tyranny of watching the stock price and quarterly earnings figures.