Apple Loses Top Spot as World's Biggest Company

Last Updated Oct 20, 2011 7:27 PM EDT

Apple is no longer the world's largest publicly traded company after losing more than $20 billion in market value in a single session.

The top spot once again belongs to energy giant Exxon Mobil (XOM), which boasts a market capitalization of $382.7 billion, according to data from Capital IQ.

Shares in Apple (AAPL) fell almost 6 percent Wednesday, hurt by a disappointing quarterly profit report, and lost nearly another 1 percent Thursday. The sell-off has cut Apple's market capitalization to $366.5 billion.

What a difference a week makes. Apple's market value hit an all-time closing high of $391.2 billion on Oct. 14 when the new iPhone 4S went on sale in seven countries. The company has lost almost $25 billion in market cap since then. For perspective, that's the equivalent of the entire market value of FedEx (FDX).

But a company's market cap changes with every up- or down-tick in the stock price, so Apple may not stay No. 2 for long.

Apple and Exxon Mobil have been trading places as "world's biggest company" for a couple of months. See the chart, courtesy of Capital IQ, below:

Traders dumped Apple's stock after earnings came in below Wall Street's forecast because of lower-than-expected iPhone sales. But that should be only a temporary problem.

Customers held off on buying iPhones in anticipation of the release of a new model (which turned out to be the iPhone 4S rather than the iPhone 5, but that's another story.)

Nevertheless, strong sales of iPhone 4S are likely setting Apple up for a huge holiday selling season. It may reclaim the top spot as world's largest publicly traded company before too long.

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    Dan Burrows, a veteran of Aol's DailyFinance, SmartMoney and MarketWatch from Dow Jones, covers the markets and economy with an eye toward investing for the long haul.