It does not take a visit to the Genius Bar to figure out how Apple became the most valuable company in America.
Its line-up of sleek phones, computers and iPods, irresistible to customers even in tough economic times, propelled it to the top position by market value, surpassing Exxon Mobil.

Apple's stock on the open market is now worth more than any other company's.

Apple's stock fell for the day, but Exxon's fell more. Apple finished with a market value of 337 billion US dollars, beating Exxon's 331 billion US dollars. A single share of Apple stock now costs 363 US dollars.

Apple occupies a rarefied spot once held by General Electric and Apple's own rival Microsoft. Exxon had held the top spot since 2005.

The power shift is a substantial milestone for Apple, which has enjoyed a triumphant comeback since the 1990s, when it struggled to stay afloat before its co-founder Steve Jobs returned to take the helm.