Are Stocks Still Good for the Long Run?

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After that boom came to a crashing end in 1929 and the market continued to implode in 1930, '31 and '32, this theoretical underpinning at first seemed to have been demolished. The idea that stocks could be good investments became a joke and remained that--in the popular view, at least--for decades. Yet whenever anyone in later years re-examined the data on stocks' long-run performance--major scholarly studies on the topic were published in 1938, '53, '64 and '76--they reached the same conclusion Smith did. Even with the dire experience of the early 1930s factored in, stocks had proved an excellent long-run investment, with returns that far outpaced those of bonds.

Finance scholars also bolted a third plank onto Smith's two reasons this was so and would continue to be: stocks were riskier than bonds, and stock investors were thus being paid a premium for taking on that additional risk.

In 1994 came the most influential of the stocks-vs.-bonds studies yet, Jeremy Siegel's Stocks for the Long Run. The book, which laid out the records of stocks and bonds going back to 1802 and found stocks winning by a mile for almost every 30-year period over those two centuries, became a must-read for investors. Siegel--a professor of finance at the University of Pennsylvania's Wharton School--became what one journalist described as "the intellectual godfather of the 1990s bull market."

In 2000, that particular bull died in the tech wreck. But unlike Edgar Lawrence Smith, who faded into obscurity after the '29 crash, Siegel has retained his reputation. That's partly because his book (the fourth edition of which was published last year) is full of warnings that when he says long run he really means long run--say, 20 to 30 years. It's also partly because in March 2000, just as the stock market was peaking, Siegel warned in a Wall Street Journal Op-Ed column that technology stocks were headed for a precipitous fall. But it's mainly that, despite the market carnage of the past year and decade, Siegel's basic argument that "stocks will remain the best investment for all those seeking long-term gains" hasn't really been discredited.

Sure, there are some market seers convinced that Siegel and his work will eventually be consigned to the dustbin of history--because they think the U.S. economy has entered into an inexorable decline. But among Siegel's fellow finance wonks, the debate isn't about his basic premise. It's about the lessons the rest of us should or shouldn't draw from it.

The Case for Bonds

In April, Robert Arnott--a veteran money manager from Southern California and former editor of the finance wonks' bible, the Financial Analysts Journal--penned a much discussed article for something called the Journal of Indexes. Arnott pointed out that while stocks still beat bonds over the long, long run, they actually lost out to 20-year government bonds from March 1969 through March 2009. That 40-year period is, by most standards, a pretty long run.