AT&T said Tuesday that it had sold more than 10 million smartphones in the fourth quarter of 2012, topping its previous record quarter of 9.4 million, set in the fourth quarter of 2011. This included best-ever quarterly sales of Android and Apple smartphones.

The news sent shares of Verizon, MetroPCS, and Leap Wireless lower, with each of the companies seeing a two percent sell off. 

AT&T's announcement comes after Verizon's Lowell McAdam said Monday during an investor conference that his company saw 2.1 million net subscriber additions. The announcement boosted Verizon's stock price late yesterday.

Still, even with the impressive smartphone sales numbers, AT&T was part of the broader downturn in stocks Tuesday. Shares of AT&T were down just under two percent to $34.35 in afternoon trading. 

Part of the investor concern over higher smartphone sales is that subsidies on the devices could decrease margins for fourth quarter. 

AT&T is scheduled to release its full fourth-quarter 2012 financial results after market close on Thursday, January 24.