Yahoo: China Snitch
Yahoo has long seen profits in China, which has led to Yahoo making outrageous transgressions. The most serious was the outing of Chinese dissidents via Yahoo mail accounts five years ago, resulting in a reporter sentenced to 10 years in prison. At first, Yahoo testified before Congress that it didn't know the nature of the dissidents' investigation, only to recant shortly after.
The ugly episode ruined Yahoo's pulling-for-the-underdog image. Yahoo has had five CEOs in the last five years, as the company struggles to remain relevant.