Index Rex

April 01, 2002


In 1896, Charles Dow created the Dow Jones Industrial Average, establishing the first measure of stock market performance and the first benchmark for portfolio performance. Limited by the technology of its times, the Dow painted a skeletal picture of the U.S. stock market. It initially consisted of just 12 stocks, weighted by their prices. As the original index, the Dow became the yardstick for relative performance.

Over the ensuing century, new technologies made it possible to create indexes that more accurately captured the performance of the U.S. stock market: for example, the Standard & Poor's 500 Index, the Russell 3000 Index, and the Wilshire 5000 Total Market Index (in ascending order of comprehensiveness). These indexes are weighted not by prices but by the market value of their constituents, and thus better represent the universe of securities available to U.S. investors.

In the mid- to late-1970s, however, a burgeoning industry of investment consultants recognized that these broad market indexes were inappropriate benchmarks for professional money managers. Most managers oversee portfolios that track not the broad market, but discrete sectors of it—stocks of a particular size, for example, or stocks with pronounced growth or value characteristics.

The consultants addressed the mismatch between managers and benchmarks by creating indexes of stocks in various capitalization ranges and of different investment styles. Since then, the industry has created multiple indexes to track every sector, industry, and subindustry. The same has happened with bonds. There are few sectors of the financial markets that are not being sliced, diced, and tortured by an ever-growing list of index creators.

Despite the proliferation of indexes, these benchmarks have generally failed to reflect the way managers actually invest. On balance, they measure the wrong set of securities¾or, if not that, then the wrong way of managing those securities. As evidence, our research shows that the correlation between the performance of growth and value managers is much higher than the correlation between growth and value indexes. In other words, the growth and value indexes reflect a degree of difference in investment styles that doesn't exist in the real world. The same problems exist with indexes that represent other subsectors of the broad market.

It is indeed puzzling that two different indexes designed to provide insight into the same sector of the marketlarge-cap value stocks, for examplecan provide very different results. The discrepancies arise, of course, because of differences in the methodologies used to create the indexes. Over long periods, different value and growth indexes generally, though not always, provide similar results. In the short run, however, their differences cause confusion and limit their usefulness as benchmarks.


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