Robert Shiller: When a Stock Market Theory Is Contagious

When a Stock Market Theory Is Contagious via Robert Shiller of The New York Times

Since Sept. 18, the stock market has fallen more than 6 percent. An abrupt decline last week — after five years of gains — prompted fears that the market may have reached a major turning point.

Has a bear market begun? It’s a great question. The problem is that short-term market movements are extremely hard to forecast. But we live in the present and must try to understand what’s driving markets now, even if it’s much easier to predict their behavior over the long run.

Fundamentally,...