Last month Yahoo co-founder Jerry Yang resigned from the company, and today the shakeup continues with AllThingsD reporting that four long-standing board members will be leaving — including the current chairman. According to the report, chairman Roy Bostock will be leaving along with Gary Wilson, Arthur Kern, and HP executive Vyomesh Joshi. Stepping in immediately will be two new directors: LiveOps chairman Maynard Webb and former Rovi CEO Fred Amoroso. Three additional board members are also said to be joining the company, but no names are given at this time.

The question of who will be taking Bostock's place as chairman is as of yet unanswered, though additional information could be included in the company's official announcement, expected later today. Yahoo's leadership has undergone a series of changes in recent years, with former PayPal president Scott Thompson taking over as CEO this past January. AllThingsD also reports that the board changes are designed partially to prevent a power struggle initiated by shareholder Daniel Loeb, who has been assembling an alternate slate of board members on his own.

Update: Yahoo has confirmed the changes in a "Chairman's Update for Shareholders," with Bostock framing them as the direct result of an internal analysis he'd instigated to determine "why Yahoo! was not meeting either our own expectations or those of our shareholders."