Measuring a brand's worth is an imprecise art. Apple has nevertheless been deemed the world's most valuable. <br /><br />At $153 billion, according to a new survey, it accounts for about half the company's market capitalisation and nearly 10 times its estimated value five years ago. <br /><br />Tech companies also populate the top ranks. There are good reasons they dominate the list - and why they're prone to big swings in value.<br /><br />The survey, by a subsidiary of WPP, estimated the earnings resulting from big brands and attempted to put a multiple on them to account for future growth. <br /><br />The result is a tech-heavy list. Google, at $111 billion, ranks second, IBM is third and Microsoft fifth.<br /><br />Al Jazeera's Rob Reynolds has the story from Los Angeles.
