Yahoo! Inc. investor Starboard Value LP nominated nine directors to replace the entire board at the struggling Web portal, which it contends has been mismanaged under Chief Executive Officer Marissa Mayer.

Starboard, a longtime critic of the company and an activist shareholder with 1.7 percent of Yahoo shares, nominated its chief executive officer, Jeffrey Smith, among others for election at Yahoo's annual meeting later this year, according to a letter to shareholders.

With little progress to show for her revival efforts after more than three years, investors are losing patience with Mayer, who has presided over sluggish sales growth and failed to separate Yahoo's main Web business from its multibillion-dollar stake in Alibaba Group Holding Ltd. Starboard first began to call for changes in 2014 and recently stepped up criticism of management, even as Yahoo said it would consider alternatives, including the sale of the company's core operations.