To Not "Screw Up" Tumblr, Yahoo Has to Reverse a History of Questionable Acquisitions

Like a Monday morning quarterback, maintaining a short memory in the crazy world of M&A is essential: especially if you're Yahoo! YHOO.

With the blessing of its board on Sunday, Yahoo acquired Tumblr, the trendy social network most popular among teens, at a favorable valuation of $1.1 billion. This means Marissa Meyer and company would shell out about a quarter of the company's cash on the chance that they can monetize the David Karp-run social network. The attempt at monetization comes as Yahoo hopes to appease the Tumblr faithful while simultaneously growing the site.

This wouldn't mark the first time Yahoo has swallowed up a booming startup, as its long list of buyouts display. Meyer has high hopes for Tumblr, but to achieve its high expectations, Yahoo will have reverse the course of a long, miserable history of unsuccessful acquisitions. Here are nine of Yahoo's most notable acquisitions gone awry.

Follow Alex Biles on Twitter at @perfectlyaloof.