08/10/2011 06:11 pm ET Updated Oct 10, 2011

10 Most Valuable Companies In America: 24/7 Wall St.

This post has been corrected.

From 24/7 Wall St.: Apple became the most valuable company in America yesterday when its market cap passed Exxon Mobil’s. The move draws attention to what market capitalization means, and why it is important. The total value of a company is driven by market forces as investors fight over the value of a company’s assets, earnings, and future business prospects. The market cap of each company is skewed by how quickly the stock trades and within what range. At any time, one of the companies on this list could pass another if a stock moves enough. The list, therefore, is hardly permanent.

Read The Ten Most Valuable Companies In America

24/7 Wall St. assembled a list of the ten most valuable companies in the U.S. We asked why they are on the list and whether their overall direction is up or down.

Here are the top ten most valuable companies in America according to 24/7 Wall St:

Most Valuable Companies

CORRECTION: A previous version of this post incorrectly put Apple's annual revenue at $100 million.