Yahoo Chairman Roy Bostock and three longtime board members are leaving the Internet company. The shake-up announced Tuesday continues a makeover of Yahoo's leadership during the past month as the company tries to win back investors frustrated with years of broken turnaround promises.

Roy Bostock is departing along with Vyomesh Joshi, Arthur Kern and Gary Wilson.

"The board has concluded that in order to accelerate the company's transformation, the combination of a new Chief Executive Officer with an enhanced team of independent directors would provide Yahoo! with the expertise and perspectives necessary to drive innovation and growth going forward. Therefore, Mr. Joshi, Mr. Kern, Mr. Wilson and I have volunteered not to stand for re-election at the next shareholders' meeting," Roy Bostock, Yahoo!'Chairman of the Board wrote in a letter to the company's shareholders.

Yahoo last month hired former PayPal executive Scott Thompson as its fourth CEO in less than five years.