Not only is Apple’s market capitalization ($143.3 billion) more than five times Dell’s ($27.3 billion), but as Roughly Drafted‘s Daniel Eran Dilger points out, it is now bigger than Dell’s (DELL) and Hewlett-Packard’s (HPQ) combined.
(Market cap is a measure of a corporation’s size and is determined by multiplying share price times the number of shares outstanding.)
This is one of those factoids made to order for WolframAlpha.
Just go to wolframalpha.com, enter “market cap of hewlett-packard, dell, apple” and voila!

