Microsoft chief executive Steve Ballmer sent Yahoo's share price plummeting on Wednesday when he denied any chance of new acquisition talks.

Speaking at a shareholder meeting in Washington, Ballmer was quoted as saying: "We are done with all acquisition discussions with Yahoo. We have moved on."

Ballmer's comments put a swift end to any speculation on the possibility of a new deal between the companies in light of Jerry Yang's departure from the chief executive position, and sent Yahoo's stock price down by as much as 20 per cent.

Yang, who co-founded the company along with David Filo, was a major opponent to Microsoft's efforts to aquire Yahoo, and led a steadfast battle against the deal by the company's board of directors.

The board's rejection of Ballmer's offers drew the ire of many shareholders, who organised an opposition campaign which ended in the appointment of Carl Icahn as a director and left both Yang and chairman Roy Bostock with low approval rates among shareholders.

Support for Yang was further eroded when the company's proposed search advertising deal with Google was called off amid mounting regulatory concerns.

The deal had been a major part of Yang's plan to increase the company's value beyond Microsoft's maximum bid of $40 per share. Yahoo's shares were trading at $9.14 at 1.30pm Pacific time.