A new evolutionary explanation of markets & investor behavior Half of all Americans have money in the stock market yet economists can't agree on whether investors & markets are rational & efficient as modern financial theory assumes or irrational & inefficient as behavioral economists believe--and as financial bubbles crashes & crises suggest This is one of the biggest debates in economics & the value or futility of investment management & financial regulation hang on the outcome In this groundbreaking book Andrew Lo cuts through this debate with a new framework the Adaptive Markets Hypothesis in which rationality & irrationality coexist Drawing on psychology evolutionary biology neuroscience artificial intelligence & other fields Adaptive Markets shows that the theory of market efficiency isn't wrong but merely incomplete When markets are unstable investors react instinctively creating inefficiencies for others to exploit Lo's new paradigm explains how financial evolution shapes behavior & markets at the speed of thought--a fact revealed by swings between stability & crisis profit & loss & innovation & regulation A fascinating intellectual journey filled with compelling stories Adaptive Markets starts with the origins of market efficiency & its failures turns to the foundations of investor behavior & concludes with practical implications--including how hedge funds have become the Galapagos Islands of finance what really happened in the 2008 meltdown & how we might avoid future crises An ambitious new answer to fundamental questions in economics Adaptive Markets is essential reading for anyone who wants to know how markets really work