Yahoo is huge. It is the fourth-biggest Internet domain in the United States. It is the fourth-biggest seller of online ads in the country. It is the most popular destination for fantasy sports, controls one the most-trafficked home pages in news, and owns the eighth-most popular email client. In the last three months, it collected more than $1 billion in revenue. It's very rich.
It's also totally worthless.
Technically, it's worse than worthless. Worthless means without worth. Worthless means $0.00. But Yahoo's core business—mostly search and display advertising—is worth more like negative-$10 billion, according to Bloomberg View's Matthew C. Klein.
The math: Yahoo's total market cap is $37 billion. Its 24 percent stake in Alibaba, the eBay of China, is worth an estimated $37 billion (Alibaba hasn't IPO'd yet, so this figure will vary), and its 35 percent stake in Yahoo Japan is worth about $10 billion. That means its core business is valued around negative-$10 billion.
It also suggests, as Klein points out, that Yahoo’s core ad-sale business has lost $12 billion in value since Marissa Mayer took over as CEO.
How is this possible? Yahoo is a profitable company. How could those profits be worth less-than-zero to shareholders?