Why Stock Markets Crash: Critical Events in Complex Financial Systems examines the mechanisms behind financial bubbles, market instability, and major stock-market crashes. Didier Sornette applies concepts from physics, mathematics, statistics, and complex-systems theory to explain how speculative bubbles can develop and eventually become unstable.

The book studies major historical episodes including the Tulip Mania, South Sea Bubble, 1929 crash, and 1987 Black Monday. It also explores positive feedback, power laws, fractals, log-periodicity, bubble modelling, and methods for analysing possible precursors of financial crashes.