UPDATE 1-Dissident Yahoo shareholder plans vote campaign

(Adds details and quotes; byline)

By Anupreeta Das

SAN FRANCISCO, May 4 (Reuters) - Dissident Yahoo Inc (YHOO.O: Quote, Profile, Research) shareholder Eric Jackson said on Sunday he plans to urge Yahoo shareholders to withhold votes from all directors at their annual meeting because the company failed to cut a deal with Microsoft Corp (MSFT.O: Quote, Profile, Research).

"Significant value was left on the table yesterday at the meeting in Seattle," Jackson said in a phone interview, adding that he and several other shareholders were surprised and disappointed at the outcome of the talks.

Jackson, who leads Plan B, a group of about 140 outspoken shareholders who collectively own 2 million Yahoo shares, said he expects Yahoo shares to slide to the "low-20s, perhaps breach $19" when the market opens on Monday. Yahoo shares closed Friday's session at $28.67 and have traded in that neighborhood since Microsoft made its offer three months ago.

"Shareholders didn't even get a chance to vote on the deal, but the board negotiated on our behalf and not in good faith," Jackson said.

Last June, Jackson became the star of Yahoo's annual meeting where he led a move to challenge the direction of the company.

At the meeting, Jackson accused the then chairman and CEO, Terry Semel, of mismanaging the company and failing to do more to revive its stock price.

Jackson, who runs investment firm Ironfire Capital, had spearheaded a move at the meeting against board-nominated directors. The campaign resulted in a hefty minority vote against the re-election of Semel, who stepped down as CEO a week later, and Roy Bostock, the current board chairman.