NEW YORK (Reuters) - Proxy advisory firm Institutional Shareholder Services on Thursday urged Clearwire Corp (>> Clearwire Corporation) shareholders to vote against majority shareholder Sprint Nextel Corp's (>> Sprint Nextel Corporation) $3.40 per share offer for Clearwire stock it does not already own.

ISS issued the advisory the day after Clearwire's board also recommended that shareholders vote against the Sprint deal and suggested that they instead accept a rival tender offer from Dish Network Corp (>> DISH Network Corp) for $4.40 per share.

The advisory firm said it revised its recommendation, which was for the Sprint deal, because the price being offered by Dish was "significantly higher than the cash consideration being offered by Sprint" and because of Clearwire's board has determined the Dish deal could be done.

Sprint declined to comment on the recommendation. It had previously argued that conditions that came with the Dish bid would make it impossible for Clearwire to accept it.

Clearwire shares closed up 10 cents, or 2 percent, at $4.47.

(Reporting by Sinead Carew; Editing by Steve Orlofsky)