Summary Box: Apple market value hits $500B

THE MILESTONE: Apple’s market capitalization topped $500 billion in trading Wednesday, climbing to a mountain peak where few companies have ventured ?and none have stayed for long.

ALREADY BIG: 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.

GOING FOR APPLE: The company had blow-out holiday-season sales of iPhones and iPads. More recently, Apple has raised investors’ hopes that it might institute a dividend. A new version of the popular iPad tablet computer is expected to be announced next week.