NEW YORK – Apple’s market capitalization topped $500 billion Wednesday, climbing to a mountain peak where few companies have ventured – and none have stayed for long.

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 blowout 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 Wednesday. Shares rose $7.03, or 1.3 percent, to $542.44.

On Tuesday, the Cupertino, Calif., company sent out invites to reporters for an event in San Francisco next Wednesday, apparently to reveal its next iPad model.

Apple is in rare company. It is the sixth U.S. corporation to reach the $500 billion milestone, and the only one to be worth that much at current prices.

Exxon, now worth $411 billion, was worth just over $500 billion for two short stretches at the end of 2007.

Apple’s arch-nemesis, Microsoft Corp., was worth just more than $500 billion briefly at the end of 1999, and again in early 2000. It even shot up above $600 billion for one day. The company is now worth $267 billion.

Cisco Systems Inc., Intel Corp. and General Electric Co. also peaked just above $500 billion in early 2000. Cisco and Intel are now worth a bit more than $100 billion each, and GE is worth $200 billion.