In an era obsessed with pint-sized enterprises rich in potential and little else, the FORTUNE 500 remains the ultimate yardstick of real corporate achievement. Yes, dot-com devotees and biotech boosters may gab about the future of their pet investments, but there's no debating the shadow that FORTUNE 500 companies cast, right now, over America's corporate landscape. The businesses on this year's 500 employed about 22 million people in 1999, more than 10% of the U.S. work force. They amassed $410 billion in profits, nearly 47% of the nation's total. And they generated $6.3 trillion in revenues, more than the combined '98 GDPs of Japan and Germany.

A single measure has always determined membership in the 500: revenues. Revenues don't depend on the whims of Wall Street, and they're less susceptible than earnings to accounting fads or outright manipulation. If you sold more than $3.03 billion in oil, microchips, or Internet access in 1999, you made the list. If you couldn't move enough widgets to fill your car's trunk, you didn't--even if your market cap was as pumped up as a former East German shot putter.

In a sense, the 500 represents the bedrock of American business, and every list is like a core sample of the year's corporate geology: Each contains traces of the economy that produced it. The 500 has always been a blend of companies that seem perpetually to tower over the rest (General Motors, Exxon, and more than 100 others that were on the list in 1955 remain there today) and companies that stay for a while before fading away or succumbing to the competition. In 1999 alone, mergers pushed Ameritech, Bankers Trust, and Mobil--to name just a few--out of the running.

The 500 has recorded each of these tales with considerable nuance and unflinching realism. GM, for example, heads the list this year for the 37th time, a portrait of dominance if ever there was one. Yet its numbers reveal a slow eclipse. In 1955 its $9.8 billion in sales accounted for 7% of the 500's total; by 1999, though sales had grown to $189 billion, they made up less than 2% of the total. Over the years many other dramas have played on the 500's stage. IBM soared in the '60s (from No. 27 to No. 6). Exxon grabbed the top spot through the oil imbroglios of the '70s. More recently the 500 has charted the rise of companies riding the Internet, like Cisco, Sun Microsystems, and Oracle. This year AOL became the first consumer Internet company to make the cut.

In this special FORTUNE 500 issue, as always, our writers have ferreted out the most intriguing tales behind the numbers. In the pages that follow, Carol J. Loomis describes No. 2 Wal-Mart's dance with the Internet, foreign markets, and its own inferiority complex. Brian O'Reilly charts the evolution of Enron (No. 18) from a boring utility into one of the world's most innovative enterprises. David Kirkpatrick uncovers the plan by Sun (No. 150) to position its servers and software at the heart of the Net. And that's just the beginning.

As for the tale of General Electric (No. 5), we'll tell that one here. As we researched this year's list, we realized that GE--for the first time ever--got more revenues from financial services (51%) than from electrical equipment (43%). Our rules required us to label the conglomerate a financial services company. When CEO Jack Welch heard about the change, he attempted, through a series of e-mails and phone calls, to persuade us to retain GE's classification as an electrical-equipment maker. That one of the world's most admired business leaders would bother to debate his place on the 500 reveals just how respected a measure it has become. But the list didn't get that way by changing its standards. And we won't change them now, Jack. Not even for you.

Vol. 141, No. 8
April 17, 2000