AMC Networks, which has vaulted into the first tier of TV programmers in recent years with shows such as “Mad Men” and “Breaking Bad,” is preparing to break from the long-established cable television business model and launch several subscription video websites, according to two people who have been involved in the project.

The first site is expected to launch later this summer, one of these people said. Rather than try to compete head-on with Netflix, Hulu, HBO and other general-interest offerings, AMC’s video sites will each focus on a specialized category, with documentaries and horror expected to be two of the initial genres.