Inefficient Markets

What this book actually teaches

Andrei Shleifer's argument in Inefficient Markets is that the efficient-market hypothesis, taken in its strong form, cannot be reconciled with the empirical record of asset prices, and that behavioral finance — the marriage of cognitive psychology and the economics of limits to arbitrage — provides a more accurate model of how real markets work. The book is based on Shleifer's Clarendon Lectures and is aimed at academic and graduate readers, not at retail investors.

The arguments build in three parts. First, the empirical critique: closed-end fund discounts, the equity-premium puzzle, post-earnings-announcement drift, momentum, long-run reversals, and bubble-and-crash episodes are difficult to square with frictionless rational pricing. Shleifer reviews the evidence carefully rather than waving at it. Second, the theoretical core: the efficient-markets defense rests on the claim that even if some investors are irrational, rational arbitrageurs will trade against them and restore prices. Shleifer and Vishny's "limits of arbitrage" framework shows why this defense fails — arbitrageurs face capital constraints, agency problems, horizon risk, and noise-trader risk, so mispricings can persist and even worsen before correcting. Third, the constructive side: he integrates investor-sentiment models (with De Long, Summers, and Waldmann, and with Barberis and Vishny) that show how representativeness, conservatism, and overconfidence can generate the very return patterns documented in the empirical literature.

The natural audience is finance PhD students, advanced MBA students, and serious practitioners who want the academic foundations of behavioral finance from someone who built them.

The weaknesses are honest. This is a lecture-derived monograph, not a textbook — it is concise and dense, and a reader who hasn't already worked through standard asset-pricing material will struggle. The behavioral models presented are stylized and have evolved substantially since 2000; later work on intermediary asset pricing, slow-moving capital, and machine-learning-driven anomaly research extends and in places revises the arguments here. The book also stays close to U.S. equities and says little about credit, currencies, or derivatives. Practitioners hoping for a trading playbook will not find one.

Worth reading for anyone who wants the foundational academic case for behavioral finance from one of its principal architects. Not the starting point for a general reader — Thaler's Misbehaving or Kahneman's Thinking, Fast and Slow are better entry points.

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About Andrei Shleifer

Read more from Andrei Shleifer and explore the full bibliography on ClearValue Books.