Apple (Nasdaq: AAPL – News) is the second-largest company in America based on its market value after oil giant Exxon Mobil (NYSE: XOM – News).

Apple is ahead of other public corporations with higher revenue, including Wal-Mart (NYSE: WMT – News), Procter & Gamble (NYSE: PG – News), Berkshire Hathaway (NYSE: BRK-B – News) and AT&T (NYSE: T – News).

The case for a continued rise in the value of Apple’s shares is compelling. It posted record revenue of $20.34 billion and net quarterly profit of $4.31 billion, or $4.64 per diluted share, in the quarter that ended September 25. Revenue was up 66% from the same quarter a year ago. iPhone sales rose 91% to 14.1 million. Many analysts who cover Apple’s stock believe that the iPhone growth rate will continue at a similar pace.Wall Street analysts say that Apple’s value is based on its rapid growth, which is not matched by any other huge U.S. company. The extremely brisk sales of Macs, iPhones and iPads are likely to accelerate as Apple picks up more sales overseas and takes market share in the U.S. from companies such as Research In Motion (Nasdaq: RIMM – News), maker of the BlackBerry, and Dell (Nasdaq: DELL – News).

The total value of Exxon Mobil’s shares creates a market cap of $362 billion. Apple’s is $284 billion. Exxon’s quarterly revenue is over $90 billion, but that figure is not growing very fast. Neither is the world’s largest company’s stock price. It has risen by 5% in the last year. Apple’s stock is up 65% over the same period.

Apple’s share price is $321, very near an all-time high. A number of analysts who cover the stock say it will go higher. Research firm Piper Jaffray recently raised its price target for Apple to $438, about 36% above its share price today. Apple’s market cap would eclipse Exxon’s if its shares hit that level.

Piper is not alone in its aggressive prediction about Apple’s share price. Goldman Sachs recently set a $430 target. Stifel Nicolaus & Co. has a target price of $390. Caris & Company’s target is $400. Many of these price forecasts are raised often as Apple’s sales numbers seem to rise sharply from earlier predictions.

Apple is expected to post an extremely good quarter for the holiday season. That, by itself, may push its stock high enough to make it the most valuable company in America.