They also believed that Tumblr would earn them $100 million in revenue in 2015. Mayer admitted during the company's latest earnings call that it wasn't able to reach that goal, because they "experienced a slower ramp in monetization than [they] initially expected." This development certainly makes it sound like Yahoo overpaid for the website a few years ago.

The blogging platform is only one of the corporate units that had to be revalued, though. In all, the company is taking a $4.5 billion charge after writing down the values of other properties. The once veritable Google rival is mired in such deep financial troubles that it's laying off thousands of employees and closing five offices. Mayer even said during the earnings call that they're considering "qualified strategic proposals," which lends credibility to earlier reports that Yahoo is thinking of selling itself off.

[Image credit: Scott Schiller/Flickr]