Thursday, August 16, 2007
Their classic 1934 textbook, “Security Analysis,” became the bible for what is now known as value investing. Warren E. Buffett took Mr. Graham’s course at Columbia Business School in the 1950s and, after working briefly for Mr. Graham’s investment firm, set out on his own to put the theories into practice. Mr. Buffett’s billions are just one part of the professors’ giant legacy.
Yet somehow, one of their big ideas about how to analyze stock prices has been almost entirely forgotten. The idea essentially reminds investors to focus on long-term trends and not to get caught up in the moment. Unfortunately, when you apply it to today’s stock market, you get even more nervous about what’s going on.
Most Wall Street analysts, of course, say there is nothing to be worried about, at least not beyond the mortgage market. In an effort to calm investors after the recent volatility, analysts have been arguing that stocks are not very expensive right now. The basis for this argument is the standard measure of the market: the price-to-earnings ratio.
It sounds like just the sort of thing the professors would have loved. In its most common form, the ratio is equal to a company’s stock price divided by its earnings per share over the last 12 months. You can skip the math, though, and simply remember that a P/E ratio tells you how much a stock costs relative to a company’s performance. The higher the ratio, the more expensive the stock is — and the stronger the argument that it won’t do very well going forward.
Right now, the stocks in the Standard & Poor’s 500-stock index have an average P/E ratio of about 16.5, which by historical standards is quite normal. Since World War II, the average P/E ratio has been 16.1. During the bubbles of the 1920s and the 1990s, on the other hand, the ratio shot above 40. The core of Wall Street’s reassuring message, then, is that even if the mortgage mess leads to a full-blown credit squeeze, the damage will not last long because stocks don’t have far to fall.
To Mr. Graham and Mr. Dodd, the P/E ratio was indeed a crucial measure, but they would have had a problem with the way that the number is calculated today. Besides advising investors to focus on the past, the two men also cautioned against putting too much emphasis on the recent past. They realized that a few months, or even a year, of financial information could be deeply misleading. It could say more about what the economy happened to be doing at any one moment than about a company’s long-term prospects.
So they argued that P/E ratios should not be based on only one year’s worth of earnings. It is much better, they wrote in “Security Analysis,” to look at profits for “not less than five years, preferably seven or ten years.”
This advice has been largely lost to history. For one thing, collecting a decade’s worth of earnings data can be time consuming. It also seems a little strange to look so far into the past when your goal is to predict future returns.
But at least two economists have remembered the advice. For years, John Y. Campbell and Robert J. Shiller have been calculating long-term P/E ratios. When they were invited to a make a presentation to Alan Greenspan in 1996, they used the statistic to argue that stocks were badly overvalued. A few days later, Mr. Greenspan touched off a brief worldwide sell-off by wondering aloud whether “irrational exuberance” was infecting the markets. In 2000, not long before the market began its real swoon, Mr. Shiller published a book that used Mr. Greenspan’s phrase as its title.
Today, the Graham-Dodd approach produces a very different picture from the one that Wall Street has been offering. Based on average profits over the last 10 years, the P/E ratio has been hovering around 27 recently. That’s higher than it has been at any other point over the last 130 years, save the great bubbles of the 1920s and the 1990s. The stock run-up of the 1990s was so big, in other words, that the market may still not have fully worked it off.
graham and dodd is in my library as it is millions of others. but i (perhaps amazingly) never read shiller's now-classic book. maybe i should. it has certainly been a basic thesis of mine that the secular bear that began in 2000 has several years left to run, and that the credit explosion of the last five years is but an intermediate stage on the path to a final, deleveraged, lower bottom -- where ten-year-trailing price-to-earnings will approach levels seen in 1982 and stock investing will be completely out of vogue for ordinary people (most of whom will consider it wildly risky or a surefire money-loser).