Shares of AMC Networks Inc. , Viacom Inc. and Discovery Inc. were down Wednesday after AT&T Inc. announced it would be dropping channels from those companies from its new DirecTV streaming packages. Viacom stock fell 4.1%, while Discovery fell 5% and AMC Networks fell 5.3%. AT&T said the two new DirecTV Now packages, called Plus and Max, would include HBO. A Plus package will cost $50 a month, AT&T said, while Max will cost $70 a month. Shares of AT&T were down 0.9% on Wednesday.