Apple's surging stock on Monday propelled Apple's value to $624 billion, surpassing the record set by Microsoft in 1999. Typically, stock hits highs in the run-up to major product launches. This time there is optimism around what is believed to be the impending launch of the iPhone 5, and possibly a smaller iPad.

Despite the surge, Apple's stock is not particularly expensive compared to its earnings for the last twelve months. For comparison, Microsoft in 1999 had a price-to-earnings ratio of 83.

Analysts speculate that a "mini iPad," could expand the number of people who can afford one of Apple's tablets. Analysts also are speculating that Apple plans to make a TV set to complete its suite of consumer electronics products.

Apple doesn't comment on its future product plans until a few weeks or days before a launch.