While Android continue to reign supremes in the device world, Google may again be losing a portion of the U.S. market to Apple. According to the latest numbers from Kantar Worldpanel, Android captured 51.1 percent of the smartphone market, but saw a decline of 7.6 percent annually. 

Apple meanwhile grew 7.8 percent annually, capturing 43.4 percent of smarpthone sales. Windows grew just half a percentage point to 3.5 percent of sales, while BlackBerry continued to lose share, falling 0.7 percent, to just 1.2 percent of all sales. 

Kantar Worldpanel's Dominic Sunnebo noted in a report that Android’s decline in sales is due to its decreasing share of first-time smartphone buyers, a key consumer group in the US, as over half of the market still own a featurephone. 

"Between July 2011 and July 2012, 52 percent of customers that bought an Android device previously owned a featurephone," Sunnebo notes. "Over this past year, that number has declined to 46 percent." 

iOS, however, has maintained its share of first-time smartphone buyers over two years (43 percent). The iPhone 4 in particular, has seen its share of purchases among first-time buyers increase, from 9 percent in July 2012 to 15 percent in July 2013, making it the top model among this consumer group. 

Sunnebo added that Microsoft’s acquisition of Nokia may lead to a larger proportion of consumers choosing a Windows device over iOS or Android, replicating the strength seen in Europe and Mexico, where lower priced Nokia handsets now represent about one in ten of every smartphone sold. 

"Windows has shown, in the past, particular strength among first-time smartphone buyers, and Nokia has benefited the most from the OS growth thus far," Sunnebo said. "Nokia, as a brand, still represents 7 percent of the featurephone market, and it is likely that many of these consumers will upgrade in the coming year.”

As part of its report, Kantar Worldpanel also lookat device sales by carrier. As with the previous period, Verizon retained its lead as the top carrier with 36.9 percent of sales, and growth of 4.1 percent over the 3 months ending July 2012. AT&T and Sprint follow with a 25.4 percent and 12.6 percent share, respectively, with both carriers seeing declines versus last year. T-Mobile remained static in 4th place, with 11 percent of sales.