IF IT'S IN THE DATA, WRITE THE PAPER. Thus begins Clifford Asness's research project with the advice of Eugene Fama, adherent of the efficient market hypothesis and presumptive skeptic of momentum in security prices. It's one of many tales from the trading floor, the seminar room, and the card table that make up Scott Patterson's The Quants: How a New Breed of Math Whizzes Conquered Wall Street and Nearly Destroyed It. Book Review No. 13 recommends The Quants as a readable, careful, intuitive explanation of some of the strategies, machinations, and personality quirks that led to multiple financial bubbles. A casual reader might infer that Wall Street is indeed a casino, as some of the quants (jargon for mathematically sophisticated arbitrage-seekers) developed some of their skills understanding games of chance, including roulette, blackjack and poker. Along the way they killed all the fun in a trading-house game called Liars Poker, in which traders attempt to estimate the frequency a digit occurs on yuppie food stamps held by the players, to the discomfiture of the frat-boy jerks who thought they understood asset trading. It is important, however, for the reader to understand the difference between a casino that manufactures risk, and an asset market that values it. Casino games are subject to the laws of large numbers in ways that asset prices are not. Nassim Taleb and Benoit Mandelbrot make cameo appearances, and the explanations of their insights in Quants is instructive. The quants, however, were slow learners. The book suggests that portfolio insurance, one mathematical breakthrough, preceded and might have precipitated the October 1987 price crash; value at risk analysis, another breakthrough, led to the failure of Long Term Capital Management in 1998, and Mr Patterson suggests new quantitative tricks led to errors in the valuation of mortgage-backed securities. He concludes with a warning that the quants are still at work on more exotic financial products, although whether they have revised their reliance on the law of large numbers remains to be seen.
(Cross-posted to 50 Book Challenge.)

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