Apple Inc is within sight of catching up with Exxon Mobil as the most valuable company in the world.

Based on Apple's growth trajectory, and a number of catalysts in the pipeline -- from a possible new iPhone this fall to expansions in China -- investors and analysts say Apple could unseat Exxon in the next six months, or latest by the middle of next year.

The market value of the top U.S. technology company was only $52 billion short of Exxon's $410 billion on Wednesday, even though the largest of the oil majors rakes in more than four times Apple's annual revenue.

In the past month alone, Apple's market capitalization has risen by $66 billion to $357.8 billion, fueled by optimism of a monstrous second half that could include the iPhone 5 and the new online music and data storage service called iCloud.

Apple has the business momentum and the growth to become the largest capitalized company in the U.S. said Tim Ghriskey, chief investment officer of Solaris Asset Management in Bedford Hills, New York. It's certainly headed in that direction. It almost seems inevitable.

The only hitch to the ascent of Apple shares would be Exxon increasing its growth on the back on higher crude oil prices, which is unlikely, Ghriskey said.

Assuming that Exxon shares stay flat, Apple will become the most valuable U.S. company when the stock hits about $444, which is only about 15 percent away from current levels.

Exxon shares have risen 14 percent so far this year, outperforming its peers. Gains have largely been fueled by high crude prices and improving demand for gasoline and diesel in developing countries.

Analysts on average expect shares of Exxon, which last paid a quarterly dividend of 47 cents in June, to climb about 12 percent in the next year to $93. This could increase its market value to $458 billion.

The estimates for Apple, on the other hand, are much higher.

Strong iPhone sales and robust growth in Asia, which helped Apple's quarterly results beat Wall Street's expectations, prompted a number of analysts to increase their price targets on Wednesday.

Wall Street now expects Apple stock to jump 25 percent on average to about $485, with Ticoderoga Securities analyst Brian White forecasting that it could reach $666, the highest target price for the stock currently.

Looking into the second-half of 2011, we believe Apple enjoys the hottest tech portfolio for the back to school season and holidays, White said. As such, we expect this rally to have legs.

Being the No.1 on the stock market would be a dramatic reversal for a company that some analysts in 2002, when Apple was in a turnaround mode, valued it based on real estate holdings and cash in hand.

CAUTION AHEAD?

In the next few months, Apple is expected to roll out the iPhone 5, which is likely to give its earnings another shot in the arm and offer a challenge to rivals such as Google Inc and Research in Motion.

Apple sold a record 20.34 million iPhones during the last quarter, even though its newest model is over a year old.

The company is also expected sign a deal with one of the largest mobile carriers in China that will likely bring millions of new consumers. Furthermore, Apple enjoys an early lead in the red-hot tablet market and sold more than 9 million iPads in the June quarter, above expectations.

While iPhones remain its flagship device, the company touted its new line of Intel-powered Mac computers on Wednesday and the latest version of its operating software, the multi-touch enabled Mac OS X Lion.

All this, along with rapid growth in emerging markets, is expected to increase Apple's revenue by 65 percent to about $107 billion this fiscal year. Exxon's revenue in 2011, on the other hand, is expected to rise 24 percent to $477 billion.

But Apple's seemingly-unstoppable momentum is not without risks.

Apart from the health of Chief Executive Steve Jobs -- a survivor of a rare form of pancreatic cancer and the inspiration behind many of Apple's most iconic products -- Wall Street is worried about the rising popularity of Google-powered smartphones.

We view Google's Android mobile operating system as a significant threat to Apple's iOS, Robert Baird analyst William Power said in a note. Android's $0 licensing fee, robust quality, and consumer-friendly interface make it an easy choice for smartphone and tablet (makers) looking to compete against the iPhone and iPad.

Also, Apple's iPod sales appears to have peaked as the market for stand-alone music players has shrunk with smartphones now rapidly eating into it. Apple expects iPod sales to fall significantly in the current quarter.

The other major risks are intensifying competition in digital content against both Google and Amazon.com, and numerous patent lawsuits, the financial implications of which are unclear.

Apple settled a case with Nokia last month and is suing Samsung Electronics, Motorola and HTC.

But for now, investors are happy with the Silicon Valley icon's market rally and expect further gains over the next few months

Historically the second half has been good for the stock, said Mike Binger, an Apple investor at Thrivent Asset Management that has about $70 billion under management. You are coming into a strong part of the selling season with back-to-school and holiday sales.

I don't think there is any hangover over the stock. Wveryone wants to find a reason not to own it, but I am in the other camp, he said.

(Additional reporting by Anna Driver in Houston; Editing by Anshuman Daga)

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