Verizon's AOL-and-Yahoo roll-up tried to build an advertising platform from telecom distribution, consumer media, and ad technology; the resulting Oath business was later written down and sold.
Yahoo bought Tumblr to regain cultural relevance, younger users, and mobile engagement. The audience remained influential, but weak monetization, strategic drift, and later resale at a fraction of the purchase price made the investment a cautionary tale.
Yahoo paid several billion dollars in stock for Broadcast.com in 1999, betting that streaming audio and video would become central to the web long before broadband economics stabilized.
Yahoo's multibillion-dollar GeoCities acquisition bought one of the web's largest user-created communities, but the portal model failed to convert that early social-web position into durable platform leadership.
Sequoia backed Yahoo before its business model was settled, betting that control of Web navigation could become a durable media and advertising asset.