Shares of Apple (Nasdaq: AAPL) spent all of Friday above the $500 billion market capitalization mark as they also set a new record of $548.21.

The shares closed at a new record, $545.18, up 71 cents, bringing the company's market value to $508.3  billion. On Tuesday, the company's market capitalization at the close was $499.2 billion.

The valuation maintains the Cupertino, Calif.-based electronics, computing, smartphone and entertainment provider as the world's most valuable company.

Shares of No. 2 ExxonMobil, the No. 1 U.S. energy company, fell 50 cents to $86.33, valuing the Houston-based company at $406.9  billion. Apple and ExxonMobil have been neck-in-neck in value at times since August.

While overall U.S. markets wre flat slightly, Apple shares gained momentum as investors anticipate new profits from sales of the long-awaited iPad 3 tablet, scheduled to be introduced next Wednesday.

Apple has sold about 55 million copies of the iPad and iPad 2, so a refreshment has long been anticipated. Apple's Asian manufacturers, mainly Taiwan's Hon Hai Precision Industries, have been working to build inventory for the new products.

Shares of Hon Hai, also known as Foxconn, were unchanged in Taipei. They are up nearly 24 percent in 2012.

Apple shares are already up 35 percent this year and 55 percent over the past 52 weeks.

Being No. 1 in value in technology can be transitory. Microsoft, Intel and Cisco Systems were all the world's most valuable companies at various points before losing the crown. Microsoft is now valued around $266 billion, Intel at $135 billion and Cisco at $107 billion.