The Nokia Lumia 521 might have competition from another Windows Phone device in the United States.

According to AdDuplex, the Lumia 521 maintained its position as the top Windows Phone device in the U.S. The Lumia 521 represented 30.2 percent of the overall Windows Phone device market share on data collected in December. The Lumia 521 was able to stay 18 percentage points ahead of the second-place challenger - the Lumia 520.

AdDuplex noted the Lumia 520 improved its rank from fifth place in November to second place. The Lumia 520 accounted for 12.2 percent of the market share.

"We have a new number 2 in the U.S. and that's the global leader - Lumia 520. Therefore, the share of Lumia 52x devices in U.S. is now pretty much aligned with global situation," stated Alan Mendelevich of AdDuplex. "It's notable that L520 has jumped 3 places in just one month and that is, most likely, the result of the aggressive pricing we've seen recently."

As Latino Post reported, the Lumia 520 was noted as the most utilized Windows Phone device in the world. The Lumia 520 was also the top Windows Phone 8 smartphone worldwide for December with 39.3 percent of the market share.

The Lumia 822 ranked third with 9.9 percent of the market share ahead of the former flagship Lumia 920 Windows Phone 8 device, which garnered 9.7 percent.

The first non-Nokia Lumia device to rank the U.S. top 10 also ranked fifth place. The HTC 8X accounted for 7.8 percent of the Windows Phone market share.

The second non-Nokia Lumia device to rank the chart was the Huawei Ascend W1, which placed eighth with 2.7 percent.

The Lumia 1020 and Lumia 710 tied at ninth place with 2.3 percent.

Among the U.S. mobile carriers, AT&T was named the top Windows Phone 8 provider with 31.7 percent of the market share ahead of T-Mobile 's 23.3 percent. Verizon Wireless fell to third place with 20.9 percent. MetroPCS rounded the top four with 10.5 percent.

"Another notable fact about U.S. is that T-Mobile is the new number 2 Windows Phone 8 operator in the country with 23.3 [percent] of the market," Mendelevich noted. "We will see if Verizon is able to come back next month when, hopefully, their new Windows Phone flagship is out. But, if history is any indication, it is the low end that drives the market share. So it is more likely that we won't see any major changes in the lineup next month."

The AdDuplex report consisted of data from 2,499 Windows Phone apps utilizing the AdDuplex SDK version 2. The data was gathered and analyzed on Dec. 27.

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