Apple has again surpassed Exxon as the most valuable US company after reporting impressive quarterly results.

Apple shares are up nearly 7% to $448.79 on Wall Street this evening, bringing the iPhone and iPad maker's market capitalisation to about $418.5 billion.

Meanwhile, Exxon Mobil shares are down 1% $86.23. That gives the oil company a market cap of about $413 billion.

California-based Apple first topped Exxon as the most valuable company in August, then fell back to second place. The Texas-based oil and gas giant had held the top spot since 2005. Apple overtook Microsoft, now in the number three slot with a market cap of $246.5 billion, in 2010.

Apple's latest quarterly results soared past expectations as US consumers snapped up near-record numbers of iPhones and iPads.

The world's most valuable technology company sold just over 37 million iPhones - its flagship product - in the three months to the end of December.

It also sold 15.43 million iPad tablet computers, doubling from a year earlier and easily outpacing already heightened expectations for a strong holiday season.

Apple's sales in the US were particularly strong, with revenue rising 90% in the Americas region. Sales in Europe were up 55%, despite the effect of the debt crisis on consumer confidence.

The consumer electronics giant said its revenue leapt 73% from a year earlier to $46.33 billion, handily beating the average Wall Street analyst estimate of $38.91 billion.

Apple reported a record net profit of $13.06 billion, or $13.87 a share. Analysts had expected Apple to earn $10.16 per share in the period, its first financial quarter.

Apple also forecast results for its second quarter that were ahead of analyst estimates. It expects revenue of about $32.5 billion and underlying earnings per share of about $8.50.

The December quarterly report marked Apple's first quarter without its legendary co-founder Steve Jobs, who died on October 5.