Apple is world's most valuable company

Apple's market capitalization topped $500 billion Wednesday, climbing to a mountain peak where few companies have ventured, and none have stayed for long, AP reported.

Apple was already the world's most valuable company. The gap between it and No. 2 Exxon Mobil Corp. has widened rapidly in the past month, as investors have digested Apple's report of blow-out holiday-season sales of iPhones and iPads. And, more recently, Apple has raised investors' hopes that it might institute a dividend.

The company's market capitalization was near $506 billion at the market close. Shares rose $7.03, or 1.3 percent, to close at $542.44 Wednesday.