Why do markets keep making bubbles when prices are supposed to be smart?

Why do markets keep making bubbles when prices are supposed to be smart?

In Robert J. Shiller’s 2013 Nobel Prize lecture, “Speculative Asset Prices,” Shiller argues that stock and housing prices often move far more than fundamentals justify, so bubbles should be understood as social epidemics shaped by stories, attention, memory, media, and imperfect but still useful financial markets.