Wal-Mart Stores Inc., the discounter that has become the dominant force in American retailing, is now the largest company in the nation and the world, capturing the top spot on the annual Fortune 500 list.

Wal-Mart, No. 2 on the list a year ago, traded places with the oil company Exxon Mobil Corp. in the rankings, compiled on the basis of companies’ annual revenue figures.

The list of America’s 500 biggest companies, has some surprises, most notably bankrupt Enron Corp. moving up two notches to No. 5 despite its downward spiral.

Fortune itself questioned why Enron stayed on the list but noted that the company benefited from the fact it, as were all energy trading companies, was allowed to include trading contracts in its revenues. Other energy trading firms also advanced in the rankings.

Wal-Mart became the first retail company to lead the 500, which until 1995 was restricted to manufacturing concerns.

Since its founding 40 years ago, Wal-Mart has seen its annual revenues and sales surge, going from $1 billion in sales for all of 1979 to sometimes generating that much in a single day last year.

Wal-Mart had $219.812 billion in revenues, compared with ExxonMobil’s $191.581 billion. Wal-Mart employs more than 1.2 million people worldwide.

The list of the largest publicly held companies has been compiled annually since 1955. General Motors Corp., which held the top spot for 15 years until 2000, stayed at No. 3 with revenues of $177.26 billion.

Despite ExxonMobil’s slip to No. 2, energy companies fared well in 2001, with ChevronTexaco at No. 8, rising from No. 20 because of the merger of Chevron Corp. and Texaco Inc.

Energy companies generally benefited because of dwindling supplies, continued utility deregulation and a continued effort by the Organization of Petroleum Exporting Countries to keep oil prices higher.

The merger of America Online and Time

Warner Inc. helped gain AOL Time Warner Inc. 37th place, making it the largest Internet and entertainment company on the list.

Computer companies were led by IBM, now
No. 9.

Microsoft Corp. rose to 72nd place from 79, and Cisco Systems Inc., which makes equipment for the Internet, advanced to No. 92 from 107, despite continued slowness in the dot-com market.

Other companies in the top 10 included Ford Motor Company, General Electric, Citigroup and Philip Morris.