Yahoo‘s appointment of Scott Thompson to the chief executive seat last week hasdan loeb photo failed to mollify at least one of the Internet company’s harshest critics.

Daniel S. Loeb, the hedge fund manager of Third Point and one of Yahoo’s largest shareholders, will be in Silicon Valley this week to interview board candidates in preparation for a possible proxy fight, according to people familiar with his plans. The investor, who has been outspoken in his contempt for Yahoo’s board, has until March 25 to file a competing slate of directors.

In recent months, Mr. Loeb has prodded Yahoo to shake-up its board and consider a sale of the entire business. In December, he vehemently opposed a sale of part of the company to private equity buyers, since such a transaction would dilute the power of existing shareholders. In a public letter, Mr. Loeb said his firm was “extremely troubled by news reports regarding the dysfunction and inequity being exhibited in the process of maximizing stockholder value that the board is allegedly ‘managing.’ ” Third Point is Yahoo’s third-largest shareholder, with a 5 percent stake.

Mr. Loeb has not decided whether he will officially instigate a proxy battle, according to people familiar with his plans who spoke on the condition of anonymity because the matter was private.