According to IHS iSuppli, the growth of the U.S. IPTV market continued to decelerate in the fourth quarter of 2012, due to the impact of Hurricane Sandy and the slowing expansion of Verizon's (NYSE:VZ) FiOS service.The two major U.S. IPTV players, Verizon and AT&T (NYSE:T), reported a combined gain of 326,000 video subscribers in the fourth quarter, down 19% from the 402,000 acquired during the same period in 2011. This marked the second consecutive year of slowing subscriber growth in the fourth quarter, with the total for the last three months of 2011 down 7% from 430,000 in 2010.For the entire year of 2012, net subscriber adds for the two U.S. IPTV services amounted to 1.3 million, down 14% from 1.5 million in 2011.Through 2017, both major U.S. IPTV players are expected to continue to see their subscriber gains moderate as the market becomes more mature. By 2017, IHS Screen Digest expects that IPTV in the United States will account for 13.4 million pay TV households, or 10.8% of all pay TV subscribers.