"I woke up one morning and just lost the desire to come into work," Siminoff wrote in an e-mail to colleagues. "I love this place; I've sweated for it and put all that I could into it. But the tank just ran dry, and my full efforts are now going to be with my daughter (and) my husband."
As first reported by CNET News.com, Siminoff will be leaving her position as senior vice president of small business and entertainment. She has been a Yahoo employee since 1996 and spearheaded the Web portal's acquisition strategy during the Internet boom years.
Siminoff's departure is the latest in a high-profile exodus of longtime Yahoo executives. In the past year and a half, CEO Timothy Koogle, Chief Financial Officer Gary Valenzuela, sales chief Anil Singh, head of international operations Heather Killen, and marketing head Karen Edwards have all left. Yahoo's current CEO, Terry Semel, has since restructured the company's management team.
During her tenure, Siminoff was instrumental in Yahoo's high-priced acquisitions of home page directory GeoCities, Web streaming media site Broadcast.com, e-mail list service eGroups and, more recently, online music site Launch Media.
The GeoCities and Broadcast.com acquisitions exemplified inflated Internet valuations during the boom years. Yahoo paid $2.87 billion and $5.04 billion in stock, respectively, for two companies that contributed to Yahoo's reach among Internet users but have since struggled for relevancy in the company.
As part of its overall restructuring unveiled Thursday before a group of financial analysts, Yahoo executives said GeoCities will focus more on selling home page publishing services for consumers and businesses. GeoCities has largely been a free service with options to upgrade for a fee.
Meanwhile, Yahoo cut a significant number of positions in Broadcast.com's enterprise Webcasting division. The cuts were part of an overall reduction of 400 employees.
"After six years at Yahoo, Ellen has made a personal decision to leave Yahoo to spend more time with her family," the company said in a statement. "Ellen has made valuable contributions to Yahoo and remains confident in the company moving forward. She will remain with the team through the end of the year."