Other big-name corporations, such as Wal-Mart Stores Inc. and General Electric Co., don't even come close. Apple overtook Microsoft Corp., the previous No. 2, just last year.
Does this mean that people need iPads more than oil?
"Exxon obviously sells a product that people need," said Brian Marshall, an analyst with Gleacher & Co. who follows Apple. "Apple sells a product that people want."
Exxon, which set a record in 2008 for the highest quarterly earnings by any company, has limited growth prospects, which are driven by oil prices and discovering new oil. It's growing, but not as quickly as Apple, which is charging ahead at the pace of a startup, Marshall says, even though the company is 35 years old.
In its latest quarterly report, Apple said that stronger iPhone and iPad sales helped more than double its net income to $7.31 billion and grow revenue by 82 percent to $28.6 billion.
Exxon Mobil, meanwhile, posted a 41 percent increase in its second-quarter earnings to $10.68 billion, the largest since it set a record of $14.8 billion in the third quarter of 2008. Its revenue grew 36 percent to $125.5 billion.
In the U.S., Exxon and General Electric had been trading off the No. 1 and No. 2 spots until Microsoft surpassed them both in early 1999, at the height of the dot-com boom. By 2000, though, GE was No. 1 once again. According to data from FactSet, the three were close over the next five years, though Apple was ascending quickly.
Marshall believes that Apple may pass yet another milestone next year, when it's likely to surpass Hewlett-Packard Co. as the world's largest technology company by revenue. In the quarter that ended in April, HP reported $31.6 billion in revenue, compared with Apple's $28.6 billion in the just-ended period. HP reports results for the May-July period next week.