Blockbuster iPhone 5 launch expected to push Apple stock to $850

Chris Whitmore with Deutsche Bank said in a note to investors on Friday that demand for the iPhone 5 is "extremely robust." Combined with a fast international launch, his prior estimates for iPhone 5 sales were too conservative.

He believes Apple could sell as many as 5 million to 6 million iPhone 5 units in the first weekend alone. Accordingly, he has raised his iPhone estimates for calendar 2012 from a previous prediction of 133 million to a new projection of 138 million.

Calendar year 2013 has been increased even more by Whitmore, from 170 million during the 12-month span to a new forecast of 180 million iPhones sold.

Whitmore sees the iPhone representing about 20 percent of total smartphone share, which would be about even with Apple's share in 2012. As such, he said his estimates could prove conservative, as he believes Apple has "ample room for additional share gains going forward."

In his eyes, Apple's continued success with the iPhone in a highly competitive smartphone market hinges upon five specific advantages:

• Apple's rich application offerings and third-party ecosystem
• The iPhone 5 is a significant form factor and radio (LTE) upgrade
• Android is likely to get more expensive or lose features as a result of litigation
• An expanded geographic reach
• Meaningful iPhone 4 and iPhone 3GS installed base upgrade potential

Whitmore also believes that Apple could see supply constraints extend into the December quarter and holiday shopping season. If that ends up being the case, sales would then be deferred to the first half of 2013, which would suggest that iPhone 5 would generate a longer, more sustained cycle.