JOHN ALLEN PAULOS Bestselling author of A MATHEMATICIAM READS THE NEWSPAPER and MATHEMATICIAN PLAYS THE w - STOCK MARKET A Mathematician Plays the Stock Market Also by John Allen Paulos Mathematics and Humor (1 980) I Think Therefore I Laugh (1 985) Innumeracy: Mathematical Illiteracy and its Consequences (1 988) Beyond Numeracy: Ruminations of a Numbers Man (1 991) A Mathematician Reads the Newspaper (1 995) Once Upon a Number: The Hidden Mathematical Logic of Stories (1 998) A Mathematician Plays the Stock Market John Allen PauIos BOOKS A Member of the Perseus Books Group Copyright O 2003 by John Allen Paulos Published by Basic Books, A Member of the Perseus Books Group All rights reserved. Printed in the United States of America. No part of this book may be reproduced in any manner whatsoever without written permission except in the case of brief quotations embodied in critical articles and reviews. For information, address Basic Books, 387 Park Avenue South, New York, NY 10016-8810. Designed by Trish Wilkinson Set in 11-point Sabon by the Perseus Books Group Library of Congress Cataloging-in-Publication Data Paulos, John Allen. A mathematician plays the stock market 1 John Allen Paulos. p. cm. Includes bibliographical references and index. ISBN 0465-05480-3 (alk. paper) 1. Investments-Psychological aspects. 2. Stock exchanges-Psychological aspects. 3. Stock exchanges-Mathematical models. 4. Investment analysis. 5. Stocks. I. Title. To my father, who never played the market and knew little about probability, yet understood one of the prime lessons of both. "Uncertainty," he would say, "is the only certainty there is, and knowing how to live with insecurity is the only security." Contents 1 Anticipating Others' Anticipations 1 Falling in Love with WorldCom Being Right Versus Being Right About the Market My Pedagogical Cruelty Common Knowledge, Jealousy, and Mar- ket Sell-Offs 2 Fear, Greed, and Cognitive Illusions 13 Averaging Down or Catching a Falling Knife? Emo- tional Overreactions and Homo Economicus Be- havioral Finance @ Psychological Foibles, A List Self-Fulfilling Beliefs and Data Mining Rumors and Online Chatrooms Pump and Dump, Short and Distort 3 Trends, Crowds, and Waves Technical Analysis: Following the Followers The Euro and the Golden Ratio Moving Averages, Big Picture Resistance and Support and All That Pre- dictability and Trends Technical Strategies and Blackjack Winning Through Losing? 4 Chance and Efficient Markets 57 Geniuses, Idiots, or Neither @ Efficiency and Random Walks Pennies and the Perception of Pattern A Stock-Newsletter Scam Decimals and Other Changes Benford's Law and Looking Out for Num- ber One The Numbers Man-A Screen Treatment viii Contents 5 Value Investing and Fundamental Analysis 85 e is the Root of All Money . The Fundamentalists' Creed: You Get What You Pay For . Ponzi and the Irrational Discounting of the Future . Average Riches, Likely Poverty . Fat Stocks, Fat People, and PIE . Contrarian Investing and the Sports Illustrated Cover Jinx . Accounting Practices, WorldCom's Problems 6 Options, Risk, and Volatility 117 Options and the Calls of the Wild . The Lure of Ille- gal Leverage . Short-Selling, Margin Buying, and Fa- milial Finances . Are Insider Trading and Stock Manipulation So Bad? . Expected Value, Not Value Expected . What's Normal? Not Six Sigma 7 Diversifying Stock Portfolios 141 A Reminiscence and a Parable . Are Stocks Less Risky Than Bonds? . The St. Petersburg Paradox and Utility . Portfolios: Benefiting from the Hatfields and McCoys . Diversification and Politically Incor- rect Funds . Beta-Is It Better? 8 Connectedness and Chaotic Price Movements 163 Insider Trading and Subterranean Information Pro- cessing . Trading Strategies, Whim, and Ant Behav- ior e Chaos and Unpredictability e Extreme Price Movements, Power Laws, and the Web . Economic Disparities and Media Disproportions 9 From Paradox to Complexity 187 The Paradoxical Efficient Market Hypothesis . The Prisoner's Dilemma and the Market . Pushing the Complexity Horizon . Game Theory and Super- natural Investor/Psychologists . Absurd Emails and the WorldCom Denouement Bibliography Index I I Anticipating Others' Anticipations I t was early 2000, the market was booming, and my invest- ments in various index funds were doing well but not gener- ating much excitement. Why investments should generate excitement is another issue, but it seemed that many people were genuinely enjoying the active management of their port- folios. So when I received a small and totally unexpected chunk of money, I placed it into what Richard Thaler, a be- havioral economist I'll return to later, calls a separate mental account. I considered it, in effect, "mad money." Nothing distinguished the money from other assets of mine except this private designation, but being so classified made my modest windfall more vulnerable to whim. In this case it entrained a series of ill-fated investment decisions that, even now, are excruciating to recall. The psychological ease with which such funds tend to be spent was no doubt a factor in my using the unexpected money to buy some shares of WorldCom (abbreviated WCOM), "the pre-eminent global communica- tions company for the digital generation," as its ads boasted, at $47 per share. (Hereafter I'll generally use WCOM to refer to the stock and WorldCom to refer to the company.) Today, of course, WorldCom is synonymous with business fraud, but in the halcyon late 1990s it seemed an irrepressibly 2 John Allen Paulos successful devourer of high-tech telecommunications compa- nies. Bernie Ebbers, the founder and former CEO, is now viewed by many as a pirate, but then he was seen as a swash- buckler. I had read about the company, knew that high-tech guru George Gilder had been long and fervently singing its praises, and was aware that among its holdings were MCI, the huge long-distance telephone company, and UUNet, the "backbone" of the Internet. I spend a lot of time on the net (home is where you hang your @) so I found Gilder's lyrical writings on the "telecosm7' and the glories of unlimited band- width particularly seductive. I also knew that, unlike most dot-com companies with no money coming in and few customers, WorldCom had more than $25 billion in revenues and almost 25 million customers, and so when several people I knew told me that WorldCom was a "strong buy," I was receptive to their suggestion. Al- though the stock had recently fallen a little in price, it was, I was assured, likely to soon surpass its previous high of $64. If this was all there was to it, there would have been no im- portant financial consequences for me, and I wouldn't be writ- ing about the investment now, Alas, there was something else, or rather a whole series of "something elses." After buying the shares, I found myself idly wondering, why not buy more? I don't think of myself as a gambler, but I willed myself not to think, willed myself simply to act, willed myself to buy more shares of WCOM, shares that cost considerably more than the few I'd already bought. Nor were these the last shares I would buy. Usually a hardheaded fellow, I was nevertheless falling disastrously in love. Although my particular heartthrob was WCOM, almost all of what I will say about my experience is unfortunately appli- cable to many other stocks and many other investors. Wher- ever WCOM appears, you may wish to substitute the symbols [...]... quantify risk? What is the role of cognitive illusion? Of common knowledge? What are the most common scams? What are A Mathematician Plays the Stock Market 5 options, portfolio theory, short-selling, the efficient market hypothesis? Does the normal bell-shaped curve explain the market' s occasional extreme volatility? What about fractals, chaos, and other non-standard tools? There will be no explicit... them with small prizes only if they pick the five contestants who receive the most votes from readers That is, they must pick the contestants that they think are most likely to be picked by the other readers, and the other readers must try to do the same They're not to become enamored of any of the contestants or otherwise give undue weight to their own taste Rather they must, in Keynes7words, anticipate...A Mathematician Plays the Stock Market 3 for Lucent, Tyco, Intel, Yahoo, AOL-Time Warner, Global Crossing, Enron, Adelphia, or, perhaps, the generic symbols WOE or BANE The time frame of the book-in the midst of a market collapse after a heady, nearly decade-long surgemay also appear rather more specific and constraining than it is Almost all the points made herein are rather general or... announcement by the Securities and Exchange Commission, the nervousness of the wives with the 12 John Allen Paulos nervousness of investors, the wives' contentment as long as their own husbands weren't straying with the investors' contentment as long their own companies weren't cooking the books, killing husbands with selling stocks, and the gap between the warning and the killings with the delay between... About the Market There's something very reductive about the stock market You can be right for the wrong reasons or wrong for the right reasons, but to the market you're just plain right or wrong Compare this to the story of the teacher who asks if anyone in the class can name two pronouns When no one volunteers, the teacher calls on Tommy who responds, "Who, me?" To the market, Tommy is right and therefore,... of the newsletter and fifty of whom chose stocks at random, then the newsletterselected stocks would achieve big gains for their investors eleven times as frequently as any particular stock did for its investors When the newsletter-selected stock is chosen by chance and happens to achieve big gains, there are fifty-five winners, the fifty believers in the newsletter and five who picked the same stock. .. each infer from the inaction of the other two of them on the first two days that their husbands were also guilty and kill them on the third day By a process of mathematical induction we can conclude that if twenty husbands are unfaithful, their intelligent wives would finally be able to prove it on the twentieth day, the day of the righteous bloodbath Now if you replace the warning of the matriarch with... notions are needed as well One of them, 10 John Allen Paulos "common knowledge," due originally to the economist Robert Aumann, is crucial to understanding the complexity of the stock market and the importance of transparency A bit of information is common knowledge among a group of people if all parties know it, know that the others know it, know that the others know they know it, and so on It is much... only their inheritances but their other investments dwindled away The "endowment effect," another kindred bias, is an inclination to endow one's holdings with more value than they have simply because one holds them "It's my stock and I love it." Related studies suggest that passively endured losses induce less regret than losses that follow active involvement Some- A Mathematician Plays the Stock Market. .. percent), and each stock of the ten has an equal chance of being smiled upon by chance (10 percent), but the newsletter-selected stock will achieve big gains much more often than the randomly selected ones 28 John A l l e n Paulos Reiterated more numerically, the claim is that 10 percent of the time the newsletter-selected stock will achieve big gains for Martha, whereas each of the ten stocks has only . JOHN ALLEN PAULOS Bestselling author of A MATHEMATICIAM READS THE NEWSPAPER and MATHEMATICIAN PLAYS THE w - STOCK MARKET A Mathematician Plays the Stock Market Also by John. Wilkinson Set in 11-point Sabon by the Perseus Books Group Library of Congress Cataloging-in-Publication Data Paulos, John Allen. A mathematician plays the stock market 1 John Allen Paulos. p What are the most common scams? What are A Mathematician Plays the Stock Market 5 options, portfolio theory, short-selling, the efficient market hypothesis? Does the normal bell-shaped curve