The hotly-anticipated iPhone 5 is likely to launch on Sept. 12, and the smartphone's sales could significantly impact not only Apple's fortunes, but the entire U.S. economy.

According to an estimate from J.P. Morgan's chief economist Michael Feroli, sales of the next-generation iPhone may boost the growth of the fourth quarter gross domestic product (GDP) in the U.S. about a third of a point.

"Calculated using the so-called retail control method, sales of iPhone 5 could boost annualized GDP growth by $3.2 billion, or $12.8 billion at an annual rate," Feroli wrote in his note to investors. Additionally, the 0.33 percentage point boost, he added, "would limit the downside risk to our Q4 GDP growth protection, which remains 2.0 percent."

Equity analysts at J.P. Morgan estimate that Apple will sell nearly 8 million iPhone 5s in the U.S. in the last quarter of 2012. The smartphone is expected to sell at the $600 price point and "would have a trade margin of $400 - adjusting for the $200 per phone in imports, a subtraction to GDP - which figures into economic growth statistics."

Reuters reported that Feroli feels that the quarter to a half point estimate of annualized GDP "seems fairly large, and for that reason should be treated skeptically." However, he averred that the "recent evidence" was in tandem with the GDP projection.

Additionally, judging by the past, the iPhone 4S sales surpassed analyst predictions and sales expectations upon launch. Feroli speculates that the iPhone 5, expected to be the "biggest product launch in consumer history", will easily pass the retail sales litmus test, so he feels that the GDP estimate "is reasonable."

"If the iPhone 5 proves to be a much larger launch - and expectations are for more significant changes than the iPhone 4 to 4S transition - it should add more than the 0.1% to 0.2%-point lift JP Morgan figures Apple provided in Q4 2011," according to Forbes,