Shares of Apple climbed $US2.44 to $US300.98 in morning trading after rising to a record $US301.72 earlier in the session.
This gives Apple a market capitalisation of about $US275 billion, above tech heavyweights such as Microsoft, Google and Hewlett-Packard.
Apple has been on a run lately, with sales of the iPad tablet surpassing expectations. Investors also have high hopes for Apple's push into China, where the iPhone maker is looking to open 25 retail stores next year.
Mounting speculation about a Verizon iPhone as soon as 2011 is also adding to Apple's appeal. Currently, the iPhone is only available from AT&T Inc. in the US
Morgan Keegan analyst Tavis McCourt said the recent $US400 million acquisition of app developer ngmoco by Japan's DeNA is also a huge plus for Apple.
Ngmoco is known for the games it makes for the iPhone, though it also plans to release apps for Android devices soon. Even so, McCourt said the pricey acquisition means even more app developers will flock to Apple's devices, where they have the best chance to make the most money.
