Microsoft may not be able to acquire Yahoo as easily as the company believes, a group of portfolio managers told reporters on Monday.

Unless Microsoft increases its bid from the current $31 (£15) per share price, a group of investors that currently owns about a quarter of Yahoo says it will not support the acquisition in the event of a proxy fight.

Throw in the small matter of Yahoo’s officers owning an additional 12 per cent of the company, and Microsoft may be facing opposition from more than one-third of the firm’s shareholders.

Stiff competition

"I'm not dying to sell at $29 (£14), which is where the deal is priced at now, or even $31 (£15) [the deal value at the time of the initial offer]," said one portfolio manager.

"I'm pretty happy to own Yahoo. And I know that if Microsoft doesn't get it now, it'll come back a year from now because it needs Yahoo."

The odds might look daunting for Microsoft, but the company remains confident that it can engage in a proxy fight and win. Nevertheless, Microsoft will admittedly need to do something to bring more shareholders to its side. Raising the offer price – a move that it has repeatedly said it will not do – could be its only option.