For most adults, the sensation of being proved right is usually a complex and bittersweet one. You might have said that your brother-in-law would turn out to be a no-goodnik, or that the forty-third President would turn out to be the worst in American history, and you may regard subsequent events as inarguable proof that you were right—but it’s not an especially happy feeling. It changes nothing about the world outside your head. You were right. Congratulations. And?

The fragility of the banks was easily disguised: “value,” in the financial markets, was as elusive as “meaning” in deconstruction. Illustration by Seymour Chwast

One of the peculiar things about the world of finance is that it freely offers the sensation of being proved right to its participants. Every transaction in the markets has a buyer and a seller, and, in most cases, one of them is right and the other wrong, because the price goes either up or down. The cumulative weight of this right-or-wrongness is one of the things that make financial types psychologically distinctive. Artists, sportsmen, surgeons, plumbers, and the rest of us have secret voices of doubt, inner reservations about ourselves, but if you go to work with money, and make money, you can be proved right in the most inhumanly pure way. This is why people who have succeeded in the world of money tend to have such a high opinion of themselves. And this is why they seem to regard themselves as paragons of rationality, while others often regard them as slightly nuts. The chairman and C.E.O. of Lehman Brothers, Richard Fuld, in his no-apologies testimony to a congressional committee after his company’s collapse, gave us a glimpse of this state of mind in its full pomp.

This is also why the financial masters of the universe tend not to write books. If you have been proved—proved—right, why bother? If you need to tell it, you can’t truly know it. The story of David Einhorn and Allied Capital is an example of a moneyman who believed, with absolute certainty, that he was in the right, who said so, and who then watched the world fail to react to his irrefutable demonstration of his own rightness. This drove him so crazy that he did what was, for a hedge-fund manager, a bizarre thing: he wrote a book about it.

The story began on May 15, 2002, when Einhorn, who runs a hedge fund called Greenlight Capital, made a speech for a children’s-cancer charity in Hackensack, New Jersey. The charity holds an annual fund-raiser at which investment luminaries give advice on specific shares. Einhorn was one of eleven speakers that day, but his speech had a twist: he recommended shorting—betting against—a firm called Allied Capital. Allied is a “business development company,” which invests in companies in their early stages. Einhorn found things not to like in Allied’s accounting practices—in particular, its way of assessing the value of its investments. The mark-to-market accounting that Einhorn favored is based on the price an asset would fetch if it were sold today, but many of Allied’s investments were in small startups that had, in effect, no market to which they could be marked. In Einhorn’s view, Allied’s way of pricing its holdings amounted to “the you-have-got-to-be-kidding-me method of accounting.” At the same time, Allied was issuing new equity, and, according to Einhorn, the revenue from this could be used to fund the dividend payments that were keeping Allied’s investors happy. To Einhorn, this looked like a potential Ponzi scheme.

The next day, Allied’s stock dipped more than twenty per cent, and a storm of controversy and counter-accusations began to rage. “Those engaging in the current misinformation campaign against Allied Capital are cynically trying to take advantage of the current post-Enron environment by tarring a great and honest company like Allied Capital with the broad brush of a Big Lie,” Allied’s C.E.O. said. Einhorn would be the first to admit that he wanted Allied’s stock to drop, which might make his motives seem impure to the general reader, but not to him. The function of hedge funds is, by his account, to expose faulty companies and make money in the process. Joseph Schumpeter described capitalism as “creative destruction”: hedge funds are destructive agents, predators targeting the weak and infirm. As Einhorn might see it, people like him are especially necessary because so many others have been asleep at the wheel. His book about his five-year battle with Allied, “Fooling Some of the People All of the Time” (Wiley; $29.95), depicts analysts, financial journalists, and the S.E.C. as being culpably complacent. The S.E.C. spent three years investigating Allied. It found that Allied violated accounting guidelines, but noted that the company had since made improvements. There were no penalties. Einhorn calls the S.E.C. judgment “the lightest of taps on the wrist with the softest of feathers.” He deeply minds this, not least because the complacency of the watchdogs prevents him from being proved right on a reasonable schedule: if they had seen things his way, Allied’s stock price would have promptly collapsed and his short selling would be hugely profitable. As it was, Greenlight shorted Allied at $26.25, only to spend the next years watching the stock drift sideways and upward; eventually, in January of 2007, it hit thirty-three dollars.

All this has a great deal of resonance now, because, on May 21st of this year, at the same charity event, Einhorn announced that Greenlight had shorted another stock, on the ground of the company’s exposure to financial derivatives based on dangerous subprime loans. The company was Lehman Brothers. There was little delay in Einhorn’s being proved right about that one: the toppling company shook the entire financial system. A global cascade of bank implosions ensued—Wachovia, Washington Mutual, and the Icelandic banking system being merely some of the highlights to date—and a global bailout of the entire system had to be put in train. The short sellers were proved right, and also came to be seen as culprits; so was mark-to-market accounting, since it caused sudden, cataclysmic drops in the book value of companies whose holdings had become illiquid. It is therefore the perfect moment for a short-selling advocate of marking to market to publish his account. One can only speculate whether Einhorn would have written his book if he had known what was going to happen next. (One of the things that have happened is that, on September 30th, Ciena Capital, an Allied portfolio company to whose fraudulent lending Einhorn dedicates many pages, went into bankruptcy; this coincided with a collapse in the value of Allied stock—finally!—to a price of around six dollars a share.) Given the esteem with which Einhorn’s profession is regarded these days, it’s a little as if the assassin of Archduke Franz Ferdinand had taken the outbreak of the First World War as the timely moment to publish a book advocating bomb-throwing—and the book had turned out to be unexpectedly persuasive.

The well-disguised fact about Einhorn, though, is that he is rather old-fashioned. His hedge fund, Greenlight, is a long-short value fund. It bets directly on companies (that is the “long,” and larger, part of the fund) or against them (that’s the “short” side). This is, in the world of high finance, not at all the new new thing. Indeed, the very fact that Einhorn is able to explain in plain English what his fund does is a sign that he isn’t at the cutting edge of finance. Another man who shuns that bleeding edge is Warren Buffett, who also happens to be quantifiably the greatest investor alive.

Buffett is unique in many respects, and one of them is his eagerness to explain how and why he does what he does. His advice sounds so plain and so reasonable—“Put your eggs in one basket, and then watch the basket”—that the reader thinks it can’t possibly be that simple. Underlying the desire to explain what he’s up to is the wish to be proved right, since Buffett regards himself as living proof that the “efficient market” theory of market pricing is wrong. The theory holds that markets, given perfect information, will always set an accurate price for a stock, one that takes full account of all the relevant probabilities and variables. Buffett thinks his own success shows that it’s possible to use generally available information to consistently outperform the market. This sounds so commonsensical that it’s hard to explain just how at odds this is with the way people have been trained to think about stock markets. Common sense is one of the hallmarks of Buffett’s writings on finance—which are, very Buffettishly, to be found pretty much nowhere other than in his annual letters to shareholders of his company, Berkshire Hathaway. Here is Buffett on the junk-bond boom, from 1989: