Apple Inc.’s next iPhone could contribute as much as one-half a percentage point to U.S. economic growth in the fourth quarter, according to an analysis by JPMorgan Chase & Co.

Apple may sell as many as 8 million iPhones in the U.S. in the final three months of the year, boosting gross domestic product by about $3.2 billion, or $12.8 billion on an annual rate, Michael Feroli, an economist at JPMorgan, wrote in a report titled “Can One Little Phone Impact GDP?”

Apple, on Sept. 12, will announce a new version of the iPhone that features a bigger screen and compatibility with faster next-generation wireless networks, people with knowledge of the matter have said. Feroli said there’s precedent for Apple’s handset boosting the economy. After the iPhone 4S was introduced last year, overall U.S. retail sales “significantly outperformed expectations,” bringing as much as two-tenths of a percentage point boost to GDP growth, he said.

The iPhone model to be introduced this week is expected to be “much larger” than last year’s device, he said. Feroli, who is JPMorgan’s chief U.S. economist, is predicting the U.S. economy will expand about 2 percent in the fourth quarter, with the iPhone limiting “downside risk.” Still, he cautioned that his estimates should be “treated skeptically.”

Apple, based in Cupertino, California, fell 2.6 percent to $662.74 in New York trading Monday. The shares have risen 64 percent this year.