Stock market technicians have developed a statistical measurement that they call beta. It empirically specifies the relative degree by which a given equity responds to a trend. If a bull leg, say, is in force, a stock's beta quotient suggests by how much that issue is apt to outperform or underperform the overall market. Less number-bound market students refer to "volatility" -- simply a general sense of whether a stock tends to move comparatively fast and far.

Whatever it is termed, according to the beta rules, a stock or group of stocks is supposed to react with equal alacrity, or lack thereof, in either direction of a trend. The INC. Index, however, has been virtually ignoring the upside, while in downtrends it has outbeta-ed just about anything that moves.Not only is that a disappointment to stockholders who expect reasonable behavior from the country's fastest growers, it is also perplexing to disinterested observers. As the charts on this page vividly show, the INC. Index fell a sorry 60 points in 12 months while the DJI gave up fewer than 10. And INC. is woefully behind even the NASDAQ Industrials -- a speculative lot whose beta is comparable to INC.'s.

The explanation appears not to lie in quality, either, since the best performing category on this page is the IPOs. In a period of dubious market action, initial public offerings outstripped DJI blue chips. While in three months the June IPOs gained over 22% as a group, AT&T, one of the bluest of the Dow, rose only about 6%. That means that a willy-nilly buying of each public offering, as obscure and untested as it may have been, would be four times more effective than owning one of America's largest companies. Nor are the rewards of such primitive investing as theoretical as they sound: Such a tactic could have been effortlessly pulled off through any broker, and the returns would actually have accrued, since INC. bases its IPO results on prices that were available in the open market.

The unfathomable aspect of this Wall Street Stonehenge is that many INC. Index companies were IPOs themselves a few months back. And they were bid up to similar heights in their day before the collapse. Why are greener stocks, many without earnings histories and some even lacking a product, advancing by double-digit increments? The answer is buried in the tangled mass psyche of stock market investment, but to the rational mind one thing seems sure: You can't have it both ways for much longer.