Yahoo Chairman Roy Bostock and three longtime board members are stepping down.

Bostock departs after four years as chairman. This position was previously held by Yahoo co-founder Jerry Yang, who resigned at the beginning of the year. Yang helped start the company in 1995.

Additionally, board members Vyomesh Joshi, Arthur Kern and Gary Wilson agreed not to seek re-election at the company's shareholders meeting this June. Joshi, a former Hewlett-Packard executive had been a director since 2005. Wilson, a former airline executive, had been a director since 2001. Kern, a former radio station owner, had been on the board for more than 15 years.

Yahoo has announced two new directors among these changes: Alfred Amoroso, former chief executive officer of Rovi and Maynard Webb, a former eBay executive who was most recently chief executive officer at LiveOps.

With these departures, all Yahoo directors will have been on the board for two years or fewer.

Yahoo said it is conducting a search for additional directors.