In this thoroughly researched and piercingly intelligent book, physicist Mark Buchanan shows how a simple feedback loop can lead to major consequences, the kind predictable by mathematical models but hard for most people to anticipate. From his unique perspective, Buchanan argues that our basic assumptions about economic markets - that they are for the most part stable, with occasional interruptions - are simply wrong. Markets really act more like weather: a brief heat wave can become a massive storm in a matter of a few days, or even hours. Forecast re-imagines the basics of the financial world, with consequences that affect everyone.