IBM’s performance since Lou Gerstner took over as chief executive in 1993 has been nothing short of remarkable—or has it?

The company has moved away from the precipice and is again one of the most-profitable companies in the U.S. Slick ads have generated the impression that IBM is once more on the cutting edge, as a leader in e-commerce technology. And the company’s stock price...oh, the stock price! The stock price has risen more than ninefold since Gerstner became chief executive.

But look a little harder, and the situation becomes less clear. When Gerstner took over, Microsoft’s stock-market value was roughly the same as the battered IBM’s. Six years later, Microsoft’s market value is almost twice IBM’s.

Microsoft isn’t so anomalous, either. Intel had about the same market value as IBM when Gerstner took office. Intel is now 10% ahead, at around $240 billion. Cisco, which challenged IBM in computer networking, has gone from a market value of $5.5 billion to $193 billion in the Gerstner years. EMC went from $1 billion to $56 billion of market value in that stretch by stealing leadership from IBM in data storage. America Online—which succeeded where IBM failed with its on-line joint venture, Prodigy—went from inconsequential levels to a market capitalization of $100 billion. In personal computers, IBM recently said it’s making progress because it may lose only hundreds of millions of dollars this year, down from about $1 billion last year. But PC leader Dell Computer measures progress a different way: Its market value has gone from $1 billion to $105 billion during the Gerstner era.

When I covered IBM for the Wall Street Journal from 1986-92, the rule of thumb was that IBM generated half the revenue of the whole computer industry and claimed two-thirds of the profits and market value. These days, depending on how the boundaries of the industry are drawn, IBM’s share of the market value is probably a percentage in the low teens.

The point here isn’t to take shots at IBM—oh, maybe a few, just for old times’ sake. The point is to show that there is often less than meets the eye when it comes to claims of success in these days of e-commerce, even if a company can point to the sort of clear improvement that Gerstner has produced at IBM.

Some other examples:

 W.W. Grainger. It introduced OrderZone in June so its customers could move their existing purchases of industrial parts on-line. Grainger said the move was a major advance. But if you want to see major advances, look at Ariba and Commerce One. Ariba provides software, and Commerce One has set up an on-line market, so that corporate customers can pretty much buy anything from anyone. While Grainger took seven decades to build to $4.3 billion of annual revenue, start-ups Ariba and Commerce One are now used to handle more than $200 billion in purchases each year. Not coincidentally, their combined market value exceeds Grainger’s $4.2 billion.

 Sotheby’s. At one point, its stock price had doubled in the past year because the strong economy had convinced so many people they just had to have that little Modigliani for their foyer. The price is still up 40% from a year ago. But eBay, the on-line auctioneer, saw its price rise by a factor of 11 since its IPO and has a market value of $11 billion, more than six times that of Sotheby’s.

 Just about every bank. Banks have been furiously gobbling each other up in the past few years, convinced that size is the key to success. Meanwhile, Intuit has been quietly assembling banking services at its Web site, which already generates huge traffic because of the popularity of Intuit’s Quicken financial software. While bank stocks lumber along, Intuit’s shares have almost doubled in the past year.

So, be even more skeptical than usual. Lots of companies are claiming victory because their stock prices are doing so well. But the real measure is how companies are doing against their competition—in other words, how much of an industry’s growth is a given company capturing? A close look would show that an awful lot of companies aren’t doing nearly as well as they think.