Source: http://mashable.com/2014/01/16/yahoo-not...

While Mayer is doubtlessly part of the reason for the increased valuation, skeptical analysts now say the company has benefited more than most realize from its 24% stake in Alibaba and that company's impending IPO. A rash of mostly small-time acquisitions has helped keep Yahoo's name in the news, but has masked the fact that its core business is still anemic. That may change now that COO Henrique de Castro is out, but until Yahoo can monetize the impressive array of new products that Yahoo has created under Mayer's tenure, she will be struggling to turn the company around.