The news media industry has changed as the internet and social media have matured and become integral to modern life. I describe these changes through a theoretical analysis of the economic structure of the industry and explore the implications for scholars of online media and politics. The crux of my argument is that social media simultaneously serves as a distribution platform and reputation builder, as social recommendations take the place of expensive investments in high-quality journalism. This development rendered crucial portions of previous models of the market for news inaccurate due to the declining importance of firm reputation. This mechanism interacts with the massive heterogeneity in digital literacy and growing animosity toward the news media among conservatives to create “credibility cascades,” which I argue are a necessary condition for Fake News to flourish.