As the market for media stocks fell, Swinburne said some companies were sold off more than their results, outlook and strategic positions would suggest. Those included Comcast, AMC Networks and Discovery Networks. Viacom, which reported a big drop in ad revenues on Thursday, was not on that list. Analyst Marci Ryvicker of Wells Fargo, who has been recommending Viacom, now says she can no longer justify giving an outperform rating to the company. "Underlying trends continue to be not just challenged, but significantly challenged despite new initiatives," Ryvicker said in a new report.