Rejected by the founding families of Hewlett-Packard, the fate of chief executive Carly Fiorina's ambitious bid to acquire Compaq now rests with the professional fund managers who constitute a silent majority of shareholders.

Ms Fiorina faces an uphill fight to clinch enough of their support to close the deal, but at least the money managers she must win over are paid to weigh risks solely against potential rewards, without regard to family legacy or corporate tradition, analysts said.

Friday's decision by HP's largest shareholder, a Packard family foundation, to side with the other children of company founders Bill Hewlett and Dave Packard against the deal, struck a potentially fatal blow to the merger by creating an opposition block of 18 per cent of the company's stock.

Shares in HP jumped 6 per cent to $25.01 (€28.24) in after-hours trade on Friday following the Packard trust's announcement, and Compaq, seen as getting the most from the merger, tumbled 12 per cent to $10.00, showing the scepticism toward the deal.

The founding families will vote 18 per cent of HP stock against the merger. Retail investors appear to have a further 25 per cent, leaving institutional investors with 57 per cent.

Walter Hewlett, the first family member who publicly opposed the deal, has said it would saddle the company with a big, low-profit personal computer division and dilute the value of the printing division, but the Packard foundation referred to its own best interests and said it understood the strategic considerations being addressed by management.

HP and Compaq say they will create a high-end computer and technology services powerhouse that can offer customers nearly everything they need, which they say is the key to growth.

Analysts have said the problems of integrating the companies present the biggest risk to the merger, should it go forward.