In Q3 2011, HTC shipped 5.7 million smartphones under its own brand in the U.S., the world's largest smartphone market, plus an additional 70,000 units under the T-Mobile brand, Canalys reports.

Samsung, meanwhile, took second place in the U.S. by shipping 4.9 million smartphones. Apple, which shipped 4.6 million iPhones, fell to third.

Apple's Drop

Like most industry watchers, Canalys says that Apple's relatively weak performance in Q3 was likely due to potential customers postponing their purchases until the arrival of the next-generation iPhone, now known as the .

"Apple did not stir the usual excitement levels in the industry with the announcement of the iPhone 4S, but that was never likely to dampen volumes, due to pent up demand from the later than expected launch and the addition of Sprint as a third carrier," Canalys analyst Chris Jones said in a statement. "Early iPhone 4S sales have shown this is the case, and we expect to see a strong Q4 for Apple."